Stockfish 17.1

Official release version of Stockfish 17.1

Bench: 2030154

---

Stockfish 17.1

Today, we have the pleasure to announce Stockfish 17.1. As always, you can
**freely** download it at [stockfishchess.org/download][1] and use it in the
[GUI of your choice][2].

Join our [Discord server][3] to get in touch with the community of developers
and users of the project!

Quality of chess play

In our testing against its predecessor, Stockfish 17.1 shows a consistent
improvement in performance, with an [Elo gain of up to 20 points][4] and
winning close to 2 times more game pairs than it loses.

Update highlights

New speedtest command

The new `speedtest` command benchmarks your computer's performance (measured in
nodes per second) using a realistic and stable test. To run it, you'll need
[command line access][5]—give it a try and share your results with the
community!

Improved hardware support

Stockfish is [no longer limited to 1024 threads][6] and will allow users to
specify whatever their system is capable of. Additionally, hardware such as
ppc64 and Loongson is now better supported at build time.

Bug fixes for tablebase support

Our previous release introduced improved engine lines (principal variations)
ending in mate as soon as a mate score is announced. A side effect of this
improvement was a [rare corner case][7] involving cursed tablebase wins, only
relevant in correspondence chess when the 50-move rule does not apply,  which
has now been fixed. Relatedly, [time management][8] has also been improved to
avoid potential time losses.

Shoutouts

Download page redesign

We've redesigned the [download page][1] to address unclear wording and simplify
a previously cluttered experience. The page now features a modernized layout,
streamlined navigation, and clearer guidance to help you select the right
binary for your system.

Fishtest framework

Our testing framework has been improved in various ways, both on the worker
side, including the adoption of [Fastchess][9] as a new game manager, and on
the server side, such as streamlined configuration. The reliable availability
of testing resources is key for the progress of the engine.

Thank you

The Stockfish project builds on a thriving community of enthusiasts (thanks
everybody!) who contribute their expertise, time, and resources to build a free
and open-source chess engine that is robust, widely available, and very strong.

We would like to express our gratitude for the [12k stars][10] that light up
our GitHub project! Thank you for your support and encouragement – your
recognition means a lot to us.

We invite our chess fans to [join the Fishtest testing framework][11] to
contribute compute resources needed for development. Programmers can contribute
to the project either directly to [Stockfish][12] (C++), to [Fishtest][13]
(HTML, CSS, JavaScript, and Python), to our trainer [nnue-pytorch][14] (C++ and
Python), or to our [website][15] (HTML, CSS/SCSS, and JavaScript).

The Stockfish team

[1]: https://stockfishchess.org/download
[2]: https://official-stockfish.github.io/docs/stockfish-wiki/Download-and-usage.html#download-a-chess-gui
[3]: https://discord.gg/GWDRS3kU6R
[4]: https://tests.stockfishchess.org/tests/view/67e7d2fd6682f97da2178fbd
[5]: https://official-stockfish.github.io/docs/stockfish-wiki/UCI-&-Commands.html#speedtest
[6]: https://github.com/official-stockfish/Stockfish/commit/652a8874b523360a3b19c5003c8ba9894ac54d0f
[7]: https://github.com/official-stockfish/Stockfish/commit/6c7c5c7e471c16f14518229428e51a3e00c0f1dd
[8]: https://github.com/official-stockfish/Stockfish/commit/0f9ae0d11cd034288a49ef3892c580dfed025091
[9]: https://github.com/Disservin/fastchess
[10]: https://github.com/official-stockfish/Stockfish/stargazers
[11]: https://official-stockfish.github.io/docs/fishtest-wiki/Running-the-Worker.html
[12]: https://github.com/official-stockfish/Stockfish
[13]: https://github.com/official-stockfish/fishtest
[14]: https://github.com/official-stockfish/nnue-pytorch
[15]: https://github.com/official-stockfish/stockfish-web

.github/ci/matrix.json

@@ -1,8 +1,8 @@
 {
   "config": [
     {
-      "name": "Ubuntu 20.04 GCC",
-      "os": "ubuntu-20.04",
+      "name": "Ubuntu 22.04 GCC",
+      "os": "ubuntu-22.04",
       "simple_name": "ubuntu",
       "compiler": "g++",
       "comp": "gcc",
@@ -111,7 +111,7 @@
     {
       "binaries": "x86-64-avxvnni",
       "config": {
-        "ubuntu-20.04": null
+        "ubuntu-22.04": null
       }
     },
     {
@@ -153,7 +153,7 @@
     {
       "binaries": "apple-silicon",
       "config": {
-        "os": "ubuntu-20.04"
+        "os": "ubuntu-22.04"
       }
     }
   ]

.github/workflows/clang-format.yml

@@ -18,7 +18,7 @@ permissions:
 jobs:
   Clang-Format:
     name: Clang-Format
-    runs-on: ubuntu-20.04
+    runs-on: ubuntu-22.04
     steps:
       - uses: actions/checkout@v4
         with:

.github/workflows/games.yml

@@ -19,22 +19,22 @@ jobs:
         working-directory: Stockfish/src
         run: make -j build debug=yes
 
-      - name: Checkout fast-chess repo
+      - name: Checkout fastchess repo
         uses: actions/checkout@v4
         with:
-          repository: Disservin/fast-chess
-          path: fast-chess
-          ref: d54af1910d5479c669dc731f1f54f9108a251951
+          repository: Disservin/fastchess
+          path: fastchess
+          ref: 894616028492ae6114835195f14a899f6fa237d3
           persist-credentials: false
 
-      - name: fast-chess build
-        working-directory: fast-chess
+      - name: fastchess build
+        working-directory: fastchess
         run: make -j
 
       - name: Run games
-        working-directory: fast-chess
+        working-directory: fastchess
         run: |
-          ./fast-chess  -rounds 4 -games 2 -repeat -concurrency 4 -openings file=app/tests/data/openings.epd format=epd order=random -srand $RANDOM\
+          ./fastchess -rounds 4 -games 2 -repeat -concurrency 4 -openings file=app/tests/data/openings.epd format=epd order=random -srand $RANDOM\
                -engine name=sf1 cmd=/home/runner/work/Stockfish/Stockfish/Stockfish/src/stockfish\
                -engine name=sf2 cmd=/home/runner/work/Stockfish/Stockfish/Stockfish/src/stockfish\
                -ratinginterval 1 -report penta=true -each proto=uci tc=4+0.04 -log file=fast.log | tee fast.out

.github/workflows/matetrack.yml

@@ -24,7 +24,7 @@ jobs:
         with:
           repository: vondele/matetrack
           path: matetrack
-          ref: 814160f82e6428ed2f6522dc06c2a6fa539cd413
+          ref: 4f8a80860ed8f3607f05a9195df8b40203bdc360
           persist-credentials: false
 
       - name: matetrack install deps
@@ -50,5 +50,22 @@ jobs:
       - name: Run matetrack
         working-directory: matetrack
         run: |
-          python matecheck.py  --syzygyPath 3-4-5-wdl/:3-4-5-dtz/ --engine /home/runner/work/Stockfish/Stockfish/Stockfish/src/stockfish --epdFile mates2000.epd --nodes 100000 | tee matecheckout.out
+          python matecheck.py --syzygyPath 3-4-5-wdl/:3-4-5-dtz/ --engine /home/runner/work/Stockfish/Stockfish/Stockfish/src/stockfish --epdFile mates2000.epd --nodes 100000 | tee matecheckout.out
           ! grep "issues were detected" matecheckout.out > /dev/null
+
+      - name: Run matetrack with --syzygy50MoveRule false
+        working-directory: matetrack
+        run: |
+          grep 5men cursed.epd > cursed5.epd
+          python matecheck.py --syzygyPath 3-4-5-wdl/:3-4-5-dtz/ --engine /home/runner/work/Stockfish/Stockfish/Stockfish/src/stockfish --epdFile cursed5.epd --nodes 100000 --syzygy50MoveRule false | tee matecheckcursed.out
+          ! grep "issues were detected" matecheckcursed.out > /dev/null
+
+      - name: Verify mate and TB win count for matecheckcursed.out
+        working-directory: matetrack
+        run: |
+          mates=$(grep "Found mates:" matecheckcursed.out | awk '{print $3}')
+          tbwins=$(grep "Found TB wins:" matecheckcursed.out | awk '{print $4}')
+          if [ $(($mates + $tbwins)) -ne 32 ]; then
+            echo "Sum of mates and TB wins is not 32 in matecheckcursed.out" >&2
+            exit 1
+          fi

.github/workflows/sanitizers.yml

@@ -21,19 +21,28 @@ jobs:
         sanitizers:
           - name: Run with thread sanitizer
             make_option: sanitize=thread
+            cxx_extra_flags: ""
             instrumented_option: sanitizer-thread
           - name: Run with UB sanitizer
             make_option: sanitize=undefined
+            cxx_extra_flags: ""
             instrumented_option: sanitizer-undefined
           - name: Run under valgrind
             make_option: ""
+            cxx_extra_flags: ""
             instrumented_option: valgrind
           - name: Run under valgrind-thread
             make_option: ""
+            cxx_extra_flags: ""
             instrumented_option: valgrind-thread
           - name: Run non-instrumented
             make_option: ""
+            cxx_extra_flags: ""
             instrumented_option: none
+          - name: Run with glibcxx assertions
+            make_option: ""
+            cxx_extra_flags: -D_GLIBCXX_ASSERTIONS
+            instrumented_option: non
     defaults:
       run:
         working-directory: src
@@ -72,7 +81,7 @@ jobs:
 
       - name: ${{ matrix.sanitizers.name }}
         run: |
-          export CXXFLAGS="-O1 -fno-inline"
+          export CXXFLAGS="-O1 -fno-inline ${{ matrix.sanitizers.cxx_extra_flags }}"
           make clean
           make -j4 ARCH=x86-64-sse41-popcnt ${{ matrix.sanitizers.make_option }} debug=yes optimize=no build > /dev/null
-          ../tests/instrumented.sh --${{ matrix.sanitizers.instrumented_option }}
+          python3 ../tests/instrumented.py --${{ matrix.sanitizers.instrumented_option }} ./stockfish

.github/workflows/tests.yml

@@ -13,15 +13,15 @@ jobs:
       fail-fast: false
       matrix:
         config:
-          - name: Ubuntu 20.04 GCC
-            os: ubuntu-20.04
+          - name: Ubuntu 22.04 GCC
+            os: ubuntu-22.04
             compiler: g++
             comp: gcc
             run_32bit_tests: true
             run_64bit_tests: true
             shell: bash
-          - name: Ubuntu 20.04 Clang
-            os: ubuntu-20.04
+          - name: Ubuntu 22.04 Clang
+            os: ubuntu-22.04
             compiler: clang++
             comp: clang
             run_32bit_tests: true
@@ -139,11 +139,11 @@ jobs:
       - name: Build Docker container
         if: matrix.config.base_image
         run: |
-          docker buildx build --load -t sf_builder - << EOF
+          docker buildx build --platform ${{ matrix.config.platform }} --load -t sf_builder - << EOF
           FROM ${{ matrix.config.base_image }}
           WORKDIR /app
           RUN apk update && apk add make g++
-          CMD ["sh", "script.sh"]
+          CMD ["sh", "src/script.sh"]
           EOF
 
       - name: Download required macOS packages
@@ -176,7 +176,7 @@ jobs:
             $COMPCXX -v
           else
             echo "$COMPCXX -v" > script.sh
-            docker run --rm --platform ${{ matrix.config.platform }} -v ${{ github.workspace }}/src:/app sf_builder
+            docker run --rm --platform ${{ matrix.config.platform }} -v ${{ github.workspace }}:/app sf_builder
           fi
 
       - name: Test help target
@@ -342,8 +342,8 @@ jobs:
       - name: Test riscv64 build
         if: matrix.config.run_riscv64_tests
         run: |
-          echo "export LDFLAGS='-static' && make clean && make -j4 ARCH=riscv64 build" > script.sh
-          docker run --rm --platform ${{ matrix.config.platform }} -v ${{ github.workspace }}/src:/app sf_builder
+          echo "cd src && export LDFLAGS='-static' && make clean && make -j4 ARCH=riscv64 build" > script.sh
+          docker run --rm --platform ${{ matrix.config.platform }} -v ${{ github.workspace }}:/app sf_builder
           ../tests/signature.sh $benchref
 
       # ppc64 tests
@@ -351,8 +351,8 @@ jobs:
       - name: Test ppc64 build
         if: matrix.config.run_ppc64_tests
         run: |
-          echo "export LDFLAGS='-static' && make clean && make -j4 ARCH=ppc-64 build" > script.sh
-          docker run --rm --platform ${{ matrix.config.platform }} -v ${{ github.workspace }}/src:/app sf_builder
+          echo "cd src && export LDFLAGS='-static' && make clean && make -j4 ARCH=ppc-64 build" > script.sh
+          docker run --rm --platform ${{ matrix.config.platform }} -v ${{ github.workspace }}:/app sf_builder
           ../tests/signature.sh $benchref
 
       # Other tests

.github/workflows/upload_binaries.yml

@@ -59,6 +59,7 @@ jobs:
           mv "${{ matrix.config.simple_name }} ${{ matrix.binaries }}" stockfish-workflow
           cd stockfish-workflow
           cp -r src ../stockfish/
+          cp -r scripts ../stockfish/
           cp stockfish-$NAME-$BINARY$EXT ../stockfish/
           cp "Top CPU Contributors.txt" ../stockfish/
           cp Copying.txt ../stockfish/

.gitignore

@@ -10,3 +10,8 @@ src/-lstdc++.res
 # Neural network for the NNUE evaluation
 **/*.nnue
 
+# Files generated by the instrumented tests
+tsan.supp
+__pycache__/
+tests/syzygy
+tests/bench_tmp.epd

AUTHORS

@@ -45,7 +45,9 @@ Bruno de Melo Costa (BM123499)
 Bruno Pellanda (pellanda)
 Bryan Cross (crossbr)
 candirufish
+Carlos Esparza Sánchez (ces42)
 Chess13234
+Chris Bao (sscg13)
 Chris Cain (ceebo)
 Ciekce
 clefrks
@@ -123,10 +125,12 @@ jundery
 Justin Blanchard (UncombedCoconut)
 Kelly Wilson
 Ken Takusagawa
+Kenneth Lee (kennethlee33)
 Kian E (KJE-98)
 kinderchocolate
 Kiran Panditrao (Krgp)
 Kojirion
+Krisztián Peőcz
 Krystian Kuzniarek (kuzkry)
 Leonardo Ljubičić (ICCF World Champion)
 Leonid Pechenik (lp--)
@@ -143,6 +147,7 @@ Maciej Żenczykowski (zenczykowski)
 Malcolm Campbell (xoto10)
 Mark Tenzer (31m059)
 marotear
+Mathias Parnaudeau (mparnaudeau)
 Matt Ginsberg (mattginsberg)
 Matthew Lai (matthewlai)
 Matthew Sullivan (Matt14916)
@@ -176,6 +181,7 @@ Ofek Shochat (OfekShochat, ghostway)
 Ondrej Mosnáček (WOnder93)
 Ondřej Mišina (AndrovT)
 Oskar Werkelin Ahlin
+Ömer Faruk Tutkun (OmerFarukTutkun)
 Pablo Vazquez
 Panthee
 Pascal Romaret
@@ -237,6 +243,7 @@ Unai Corzo (unaiic)
 Uri Blass (uriblass)
 Vince Negri (cuddlestmonkey)
 Viren
+Wencey Wang
 windfishballad
 xefoci7612
 Xiang Wang (KatyushaScarlet)

CONTRIBUTING.md

@@ -49,7 +49,7 @@ further discussion._
 - Provide a clear and concise description of the changes in the pull request
   description.
 
-_First time contributors should add their name to [AUTHORS](../AUTHORS)._
+_First time contributors should add their name to [AUTHORS](./AUTHORS)._
 
 _Stockfish's development is not focused on adding new features. Thus any pull
 request introducing new features will potentially be closed without further
@@ -86,7 +86,6 @@ more details.
 
 Thank you for contributing to Stockfish and helping us make it even better!
 
-
 [copying-link]:           https://github.com/official-stockfish/Stockfish/blob/master/Copying.txt
 [discord-link]:           https://discord.gg/GWDRS3kU6R
 [discussions-link]:       https://github.com/official-stockfish/Stockfish/discussions/new

README.md

@@ -97,7 +97,7 @@ descriptions. An example suitable for most Intel and AMD chips:
 
 ```
 cd src
-make -j profile-build ARCH=x86-64-avx2
+make -j profile-build
 ```
 
 Detailed compilation instructions for all platforms can be found in our
@@ -120,6 +120,11 @@ where the source code can be found) to generate the exact binary you are
 distributing. If you make any changes to the source code, these changes must
 also be made available under GPL v3.
 
+## Acknowledgements
+
+Stockfish uses neural networks trained on [data provided by the Leela Chess Zero
+project][lc0-data-link], which is made available under the [Open Database License][odbl-link] (ODbL).
+
 
 [authors-link]:       https://github.com/official-stockfish/Stockfish/blob/master/AUTHORS
 [build-link]:         https://github.com/official-stockfish/Stockfish/actions/workflows/stockfish.yml
@@ -144,6 +149,8 @@ also be made available under GPL v3.
 [wiki-uci-link]:      https://github.com/official-stockfish/Stockfish/wiki/UCI-&-Commands
 [wiki-usage-link]:    https://github.com/official-stockfish/Stockfish/wiki/Download-and-usage
 [worker-link]:        https://github.com/official-stockfish/fishtest/wiki/Running-the-worker
+[lc0-data-link]:      https://storage.lczero.org/files/training_data
+[odbl-link]:          https://opendatacommons.org/licenses/odbl/odbl-10.txt
 
 [build-badge]:        https://img.shields.io/github/actions/workflow/status/official-stockfish/Stockfish/stockfish.yml?branch=master&style=for-the-badge&label=stockfish&logo=github
 [commits-badge]:      https://img.shields.io/github/commits-since/official-stockfish/Stockfish/latest?style=for-the-badge

Top CPU Contributors.txt

@@ -1,118 +1,126 @@
-Contributors to Fishtest with >10,000 CPU hours, as of 2024-08-31.
+Contributors to Fishtest with >10,000 CPU hours, as of 2025-03-22.
 Thank you!
 
 Username                                CPU Hours     Games played
 ------------------------------------------------------------------
-noobpwnftw                               40428649       3164740143
-technologov                              23581394       1076895482
-vdv                                      19425375        718302718
-linrock                                  10034115        643194527
+noobpwnftw                               41712226       3294628533
+vdv                                      28993864        954145232
+technologov                              24984442       1115931964
+linrock                                  11463033        741692823
 mlang                                     3026000        200065824
-okrout                                    2572676        237511408
-pemo                                      1836785         62226157
+okrout                                    2726068        248285678
+olafm                                     2420096        161297116
+pemo                                      1838361         62294199
+TueRens                                   1804847         80170868
 dew                                       1689162        100033738
-TueRens                                   1648780         77891164
-sebastronomy                              1468328         60859092
-grandphish2                               1466110         91776075
+sebastronomy                              1655637         67294942
+grandphish2                               1474752         92156319
 JojoM                                     1130625         73666098
-olafm                                     1067009         74807270
+rpngn                                      973590         59996557
+oz                                         921203         60370346
 tvijlbrief                                 796125         51897690
-oz                                         781847         53910686
-rpngn                                      768460         49812975
-gvreuls                                    751085         52177668
+gvreuls                                    792215         55184194
 mibere                                     703840         46867607
-leszek                                     566598         42024615
-cw                                         519601         34988161
+leszek                                     599745         44681421
+cw                                         519602         34988289
 fastgm                                     503862         30260818
-CSU_Dynasty                                468784         31385034
-maximmasiutin                              439192         27893522
-ctoks                                      435148         28541909
+CSU_Dynasty                                474794         31654170
+maximmasiutin                              441753         28129452
+robal                                      437950         28869118
+ctoks                                      435150         28542141
 crunchy                                    427414         27371625
 bcross                                     415724         29061187
-robal                                      371112         24642270
-mgrabiak                                   367963         26464704
+mgrabiak                                   380202         27586936
 velislav                                   342588         22140902
 ncfish1                                    329039         20624527
 Fisherman                                  327231         21829379
+Sylvain27                                  317021         11494912
+marrco                                     310446         19587107
 Dantist                                    296386         18031762
-tolkki963                                  262050         22049676
-Sylvain27                                  255595          8864404
+Fifis                                      289595         14969251
+tolkki963                                  286043         23596996
+Calis007                                   272677         17281620
+cody                                       258835         13301710
 nordlandia                                 249322         16420192
-Fifis                                      237657         13065577
-marrco                                     234581         17714473
-Calis007                                   217537         14450582
+javran                                     212141         16507618
 glinscott                                  208125         13277240
 drabel                                     204167         13930674
 mhoram                                     202894         12601997
 bking_US                                   198894         11876016
+Wencey                                     198537          9606420
 Thanar                                     179852         12365359
-javran                                     169679         13481966
-armo9494                                   162863         10937118
+sschnee                                    170521         10891112
+armo9494                                   168141         11177514
+DesolatedDodo                              160605         10392474
 spams                                      157128         10319326
-DesolatedDodo                              156683         10211206
-Wencey                                     152308          8375444
+maposora                                   155839         13963260
 sqrt2                                      147963          9724586
-vdbergh                                    140311          9225125
+vdbergh                                    140514          9242985
 jcAEie                                     140086         10603658
 CoffeeOne                                  137100          5024116
 malala                                     136182          8002293
+Goatminola                                 134893         11640524
 xoto                                       133759          9159372
-Dubslow                                    129614          8519312
+markkulix                                  132104         11000548
+naclosagc                                  131472          4660806
+Dubslow                                    129685          8527664
 davar                                      129023          8376525
 DMBK                                       122960          8980062
 dsmith                                     122059          7570238
-CypressChess                               120784          8672620
-sschnee                                    120526          7547722
-maposora                                   119734         10749710
+Wolfgang                                   120919          8619168
+CypressChess                               120902          8683904
 amicic                                     119661          7938029
-Wolfgang                                   115713          8159062
+cuistot                                    116864          7828864
+sterni1971                                 113754          6054022
 Data                                       113305          8220352
 BrunoBanani                                112960          7436849
-markkulix                                  112897          9133168
-cuistot                                    109802          7121030
+megaman7de                                 109139          7360928
 skiminki                                   107583          7218170
-sterni1971                                 104431          5938282
+zeryl                                      104523          6618969
 MaZePallas                                 102823          6633619
 sunu                                       100167          7040199
-zeryl                                       99331          6221261
-thirdlife                                   99156          2245320
+thirdlife                                   99178          2246544
 ElbertoOne                                  99028          7023771
-megaman7de                                  98456          6675076
-Goatminola                                  96765          8257832
+TataneSan                                   97257          4239502
+romangol                                    95662          7784954
 bigpen0r                                    94825          6529241
 brabos                                      92118          6186135
 Maxim                                       90818          3283364
 psk                                         89957          5984901
+szupaw                                      89775          7800606
+jromang                                     87260          5988073
 racerschmacer                               85805          6122790
 Vizvezdenec                                 83761          5344740
 0x3C33                                      82614          5271253
-szupaw                                      82495          7151686
+Spprtr                                      82103          5663635
 BRAVONE                                     81239          5054681
+MarcusTullius                               78930          5189659
+Mineta                                      78731          4947996
+Torom                                       77978          2651656
 nssy                                        76497          5259388
-cody                                        76126          4492126
-jromang                                     76106          5236025
-MarcusTullius                               76103          5061991
-woutboat                                    76072          6022922
-Spprtr                                      75977          5252287
+woutboat                                    76379          6031688
 teddybaer                                   75125          5407666
 Pking_cda                                   73776          5293873
+Viren6                                      73664          1356502
 yurikvelo                                   73611          5046822
-Mineta                                      71130          4711422
 Bobo1239                                    70579          4794999
 solarlight                                  70517          5028306
 dv8silencer                                 70287          3883992
 manap                                       66273          4121774
 tinker                                      64333          4268790
 qurashee                                    61208          3429862
-AGI                                         58195          4329580
+DanielMiao1                                 60181          1317252
+AGI                                         58316          4336328
+jojo2357                                    57435          4944212
 robnjr                                      57262          4053117
 Freja                                       56938          3733019
 MaxKlaxxMiner                               56879          3423958
 ttruscott                                   56010          3680085
 rkl                                         55132          4164467
-jmdana                                      54697          4012593
+jmdana                                      54988          4041917
 notchris                                    53936          4184018
 renouve                                     53811          3501516
+CounterFlow                                 52536          3203740
 finfish                                     51360          3370515
 eva42                                       51272          3599691
 eastorwest                                  51117          3454811
@@ -122,33 +130,36 @@ GPUex                                       48686          3684998
 OuaisBla                                    48626          3445134
 ronaldjerum                                 47654          3240695
 biffhero                                    46564          3111352
-oryx                                        45639          3546530
+oryx                                        46141          3583236
+jibarbosa                                   45890          4541218
+DeepnessFulled                              45734          3944282
+abdicj                                      45577          2631772
 VoyagerOne                                  45476          3452465
+mecevdimitar                                44240          2584396
 speedycpu                                   43842          3003273
 jbwiebe                                     43305          2805433
+gopeto                                      43046          2821514
+YvesKn                                      42628          2177630
 Antihistamine                               41788          2761312
 mhunt                                       41735          2691355
-jibarbosa                                   41640          4145702
+somethingintheshadows                       41502          3330418
 homyur                                      39893          2850481
 gri                                         39871          2515779
-DeepnessFulled                              39020          3323102
+vidar808                                    39774          1656372
 Garf                                        37741          2999686
 SC                                          37299          2731694
-Gaster319                                   37118          3279678
-naclosagc                                   36562          1279618
+Gaster319                                   37229          3289674
 csnodgrass                                  36207          2688994
+ZacHFX                                      35528          2486328
+icewulf                                     34782          2415146
 strelock                                    34716          2074055
-gopeto                                      33717          2245606
 EthanOConnor                                33370          2090311
 slakovv                                     32915          2021889
-jojo2357                                    32890          2826662
-shawnxu                                     32019          2802552
+shawnxu                                     32144          2814668
 Gelma                                       31771          1551204
-vidar808                                    31560          1351810
+srowen                                      31181          1732120
 kdave                                       31157          2198362
 manapbk                                     30987          1810399
-ZacHFX                                      30966          2272416
-TataneSan                                   30713          1513402
 votoanthuan                                 30691          2460856
 Prcuvu                                      30377          2170122
 anst                                        30301          2190091
@@ -157,145 +168,155 @@ spcc                                        29925          1901692
 hyperbolic.tom                              29840          2017394
 chuckstablers                               29659          2093438
 Pyafue                                      29650          1902349
+WoodMan777                                  29300          2579864
 belzedar94                                  28846          1811530
-mecevdimitar                                27610          1721382
 chriswk                                     26902          1868317
 xwziegtm                                    26897          2124586
+Jopo12321                                   26818          1816482
 achambord                                   26582          1767323
-somethingintheshadows                       26496          2186404
 Patrick_G                                   26276          1801617
 yorkman                                     26193          1992080
-srowen                                      25743          1490684
-Ulysses                                     25413          1702830
-Jopo12321                                   25227          1652482
+Ulysses                                     25517          1711634
 SFTUser                                     25182          1675689
 nabildanial                                 25068          1531665
 Sharaf_DG                                   24765          1786697
 rodneyc                                     24376          1416402
 jsys14                                      24297          1721230
+AndreasKrug                                 24235          1934711
 agg177                                      23890          1395014
-AndreasKrug                                 23754          1890115
 Ente                                        23752          1678188
 JanErik                                     23408          1703875
 Isidor                                      23388          1680691
 Norabor                                     23371          1603244
-WoodMan777                                  23253          2023048
 Nullvalue                                   23155          2022752
+fishtester                                  23115          1581502
+wizardassassin                              23073          1789536
+Skiff84                                     22984          1053680
 cisco2015                                   22920          1763301
+ols                                         22914          1322047
+Hjax                                        22561          1566151
 Zirie                                       22542          1472937
 team-oh                                     22272          1636708
+mkstockfishtester                           22253          2029566
 Roady                                       22220          1465606
 MazeOfGalious                               21978          1629593
 sg4032                                      21950          1643373
-tsim67                                      21747          1330880
+tsim67                                      21939          1343944
 ianh2105                                    21725          1632562
-Skiff84                                     21711          1014212
+Serpensin                                   21704          1809188
 xor12                                       21628          1680365
 dex                                         21612          1467203
 nesoneg                                     21494          1463031
+IslandLambda                                21468          1239756
 user213718                                  21454          1404128
-Serpensin                                   21452          1790510
 sphinx                                      21211          1384728
 qoo_charly_cai                              21136          1514927
-IslandLambda                                21062          1220838
 jjoshua2                                    21001          1423089
 Zake9298                                    20938          1565848
 horst.prack                                 20878          1465656
-fishtester                                  20729          1348888
 0xB00B1ES                                   20590          1208666
-ols                                         20477          1195945
 Dinde                                       20459          1292774
+t3hf1sht3ster                               20456           670646
 j3corre                                     20405           941444
+0x539                                       20332          1039516
 Adrian.Schmidt123                           20316          1281436
+malfoy                                      20313          1350694
+purpletree                                  20019          1461026
 wei                                         19973          1745989
 teenychess                                  19819          1762006
 rstoesser                                   19569          1293588
 eudhan                                      19274          1283717
+nalanzeyu                                   19211           396674
 vulcan                                      18871          1729392
-wizardassassin                              18795          1376884
 Karpovbot                                   18766          1053178
 jundery                                     18445          1115855
-mkstockfishtester                           18350          1690676
+Farseer                                     18281          1074642
+sebv15                                      18267          1262588
+whelanh                                     17887           347974
 ville                                       17883          1384026
 chris                                       17698          1487385
 purplefishies                               17595          1092533
 dju                                         17414           981289
 iisiraider                                  17275          1049015
+Karby                                       17177          1030688
 DragonLord                                  17014          1162790
-Karby                                       17008          1013160
-pirt                                        16965          1271519
+pirt                                        16991          1274215
 redstone59                                  16842          1461780
 Alb11747                                    16787          1213990
 Naven94                                     16414           951718
-scuzzi                                      16115           994341
+scuzzi                                      16155           995347
 IgorLeMasson                                16064          1147232
 ako027ako                                   15671          1173203
+xuhdev                                      15516          1528278
 infinigon                                   15285           965966
 Nikolay.IT                                  15154          1068349
 Andrew Grant                                15114           895539
 OssumOpossum                                14857          1007129
 LunaticBFF57                                14525          1190310
 enedene                                     14476           905279
-Hjax                                        14394          1005013
+YELNAMRON                                   14475          1141330
+RickGroszkiewicz                            14272          1385984
+joendter                                    14269           982014
 bpfliegel                                   14233           882523
-YELNAMRON                                   14230          1128094
 mpx86                                       14019           759568
 jpulman                                     13982           870599
 getraideBFF                                 13871          1172846
+crocogoat                                   13817          1119086
 Nesa92                                      13806          1116101
-crocogoat                                   13803          1117422
 joster                                      13710           946160
 mbeier                                      13650          1044928
 Pablohn26                                   13552          1088532
 wxt9861                                     13550          1312306
 Dark_wizzie                                 13422          1007152
 Rudolphous                                  13244           883140
+Jackfish                                    13177           894206
+MooTheCow                                   13091           892304
 Machariel                                   13010           863104
-nalanzeyu                                   12996           232590
 mabichito                                   12903           749391
-Jackfish                                    12895           868928
 thijsk                                      12886           722107
 AdrianSA                                    12860           804972
 Flopzee                                     12698           894821
-whelanh                                     12682           266404
+szczur90                                    12684           977536
+Kyrega                                      12661           456438
 mschmidt                                    12644           863193
 korposzczur                                 12606           838168
 fatmurphy                                   12547           853210
 Oakwen                                      12532           855759
-icewulf                                     12447           854878
 SapphireBrand                               12416           969604
 deflectooor                                 12386           579392
 modolief                                    12386           896470
-Farseer                                     12249           694108
+ckaz                                        12273           754644
 Hongildong                                  12201           648712
 pgontarz                                    12151           848794
 dbernier                                    12103           860824
-szczur90                                    12035           942376
-FormazChar                                  12019           910409
+FormazChar                                  12051           913497
+shreven                                     12044           884734
 rensonthemove                               11999           971993
 stocky                                      11954           699440
-MooTheCow                                   11923           779432
 3cho                                        11842          1036786
-ckaz                                        11792           732276
+ImperiumAeternum                            11482           979142
 infinity                                    11470           727027
 aga                                         11412           695127
+Def9Infinity                                11408           700682
 torbjo                                      11395           729145
 Thomas A. Anderson                          11372           732094
 savage84                                    11358           670860
-Def9Infinity                                11345           696552
 d64                                         11263           789184
 ali-al-zhrani                               11245           779246
-ImperiumAeternum                            11155           952000
+vaskoul                                     11144           953906
 snicolet                                    11106           869170
 dapper                                      11032           771402
 Ethnikoi                                    10993           945906
 Snuuka                                      10938           435504
 Karmatron                                   10871           678306
+gerbil                                      10871          1005842
+OliverClarke                                10696           942654
 basepi                                      10637           744851
+michaelrpg                                  10624           748179
 Cubox                                       10621           826448
-gerbil                                      10519           971688
-michaelrpg                                  10509           739239
+dragon123118                                10421           936506
 OIVAS7572                                   10420           995586
+GBx3TV                                      10388           339952
 Garruk                                      10365           706465
 dzjp                                        10343           732529
-RickGroszkiewicz                            10263           990798
+borinot                                     10026           902130

scripts/.gitattributes

@@ -0,0 +1 @@
+*.sh text eol=lf

scripts/get_native_properties.sh

@@ -26,6 +26,17 @@ check_znver_1_2() {
   [ "$vendor_id" = "AuthenticAMD" ] && [ "$cpu_family" = "23" ] && znver_1_2=true
 }
 
+# Set the file CPU loongarch64 architecture
+set_arch_loongarch64() {
+  if check_flags 'lasx'; then
+    true_arch='loongarch64-lasx'
+  elif check_flags 'lsx'; then
+    true_arch='lonngarch64-lsx'
+  else
+    true_arch='loongarch64'
+  fi
+}
+
 # Set the file CPU x86_64 architecture
 set_arch_x86_64() {
   if check_flags 'avx512vnni' 'avx512dq' 'avx512f' 'avx512bw' 'avx512vl'; then
@@ -43,6 +54,20 @@ set_arch_x86_64() {
   fi
 }
 
+set_arch_ppc_64() {
+  if $(grep -q -w "altivec" /proc/cpuinfo); then
+    power=$(grep -oP -m 1 'cpu\t+: POWER\K\d+' /proc/cpuinfo)
+    if [ "0$power" -gt 7 ]; then
+      # VSX started with POWER8
+      true_arch='ppc-64-vsx'
+    else
+      true_arch='ppc-64-altivec'
+    fi
+  else
+    true_arch='ppc-64'
+  fi
+}
+
 # Check the system type
 uname_s=$(uname -s)
 uname_m=$(uname -m)
@@ -51,7 +76,7 @@ case $uname_s in
     case $uname_m in
       'arm64')
         true_arch='apple-silicon'
-        file_arch='x86-64-sse41-popcnt' # Supported by Rosetta 2
+        file_arch='m1-apple-silicon'
         ;;
       'x86_64')
         flags=$(sysctl -n machdep.cpu.features machdep.cpu.leaf7_features | tr '\n' ' ' | tr '[:upper:]' '[:lower:]' | tr -d '_.')
@@ -76,6 +101,10 @@ case $uname_s in
         file_os='ubuntu'
         true_arch='x86-32'
         ;;
+      'ppc64'*)
+        file_os='ubuntu'
+        set_arch_ppc_64
+        ;;
       'aarch64')
         file_os='android'
         true_arch='armv8'
@@ -90,6 +119,10 @@ case $uname_s in
           true_arch="$true_arch-neon"
         fi
         ;;
+      'loongarch64'*)
+        file_os='linux'
+        set_arch_loongarch64
+        ;;
       *) # Unsupported machine type, exit with error
         printf 'Unsupported machine type: %s\n' "$uname_m"
         exit 1

scripts/net.sh

@@ -0,0 +1,76 @@
+#!/bin/sh
+
+wget_or_curl=$( (command -v wget > /dev/null 2>&1 && echo "wget -qO-") || \
+                (command -v curl > /dev/null 2>&1 && echo "curl -skL"))
+
+
+sha256sum=$( (command -v shasum > /dev/null 2>&1 && echo "shasum -a 256") || \
+             (command -v sha256sum > /dev/null 2>&1 && echo "sha256sum"))
+
+if [ -z "$sha256sum" ]; then
+  >&2 echo "sha256sum not found, NNUE files will be assumed valid."
+fi
+
+get_nnue_filename() {
+  grep "$1" evaluate.h | grep "#define" | sed "s/.*\(nn-[a-z0-9]\{12\}.nnue\).*/\1/"
+}
+
+validate_network() {
+  # If no sha256sum command is available, assume the file is always valid.
+  if [ -n "$sha256sum" ] && [ -f "$1" ]; then
+    if [ "$1" != "nn-$($sha256sum "$1" | cut -c 1-12).nnue" ]; then
+      rm -f "$1"
+      return 1
+    fi
+  fi
+}
+
+fetch_network() {
+  _filename="$(get_nnue_filename "$1")"
+
+  if [ -z "$_filename" ]; then
+    >&2 echo "NNUE file name not found for: $1"
+    return 1
+  fi
+
+  if [ -f "$_filename" ]; then
+    if validate_network "$_filename"; then
+      echo "Existing $_filename validated, skipping download"
+      return
+    else
+      echo "Removing invalid NNUE file: $_filename"
+    fi
+  fi
+
+  if [ -z "$wget_or_curl" ]; then
+    >&2 printf "%s\n" "Neither wget or curl is installed." \
+          "Install one of these tools to download NNUE files automatically."
+    exit 1
+  fi
+
+  for url in \
+    "https://tests.stockfishchess.org/api/nn/$_filename" \
+    "https://github.com/official-stockfish/networks/raw/master/$_filename"; do
+    echo "Downloading from $url ..."
+    if $wget_or_curl "$url" > "$_filename"; then
+      if validate_network "$_filename"; then
+        echo "Successfully validated $_filename"
+      else
+        echo "Downloaded $_filename is invalid"
+        continue
+      fi
+    else
+      echo "Failed to download from $url"
+    fi
+    if [ -f "$_filename" ]; then
+      return
+    fi
+  done
+
+  # Download was not successful in the loop, return false.
+  >&2 echo "Failed to download $_filename"
+  return 1
+}
+
+fetch_network EvalFileDefaultNameBig && \
+fetch_network EvalFileDefaultNameSmall

src/Makefile

@@ -1,5 +1,5 @@
 # Stockfish, a UCI chess playing engine derived from Glaurung 2.1
-# Copyright (C) 2004-2024 The Stockfish developers (see AUTHORS file)
+# Copyright (C) 2004-2025 The Stockfish developers (see AUTHORS file)
 #
 # Stockfish is free software: you can redistribute it and/or modify
 # it under the terms of the GNU General Public License as published by
@@ -55,9 +55,10 @@ PGOBENCH = $(WINE_PATH) ./$(EXE) bench
 SRCS = benchmark.cpp bitboard.cpp evaluate.cpp main.cpp \
 	misc.cpp movegen.cpp movepick.cpp position.cpp \
 	search.cpp thread.cpp timeman.cpp tt.cpp uci.cpp ucioption.cpp tune.cpp syzygy/tbprobe.cpp \
-	nnue/nnue_misc.cpp nnue/features/half_ka_v2_hm.cpp nnue/network.cpp engine.cpp score.cpp memory.cpp
+	nnue/nnue_accumulator.cpp nnue/nnue_misc.cpp nnue/features/half_ka_v2_hm.cpp nnue/network.cpp \
+	engine.cpp score.cpp memory.cpp
 
-HEADERS = benchmark.h bitboard.h evaluate.h misc.h movegen.h movepick.h \
+HEADERS = benchmark.h bitboard.h evaluate.h misc.h movegen.h movepick.h history.h \
 		nnue/nnue_misc.h nnue/features/half_ka_v2_hm.h nnue/layers/affine_transform.h \
 		nnue/layers/affine_transform_sparse_input.h nnue/layers/clipped_relu.h nnue/layers/simd.h \
 		nnue/layers/sqr_clipped_relu.h nnue/nnue_accumulator.h nnue/nnue_architecture.h \
@@ -98,8 +99,12 @@ VPATH = syzygy:nnue:nnue/features
 # avx512 = yes/no     --- -mavx512bw         --- Use Intel Advanced Vector Extensions 512
 # vnni256 = yes/no    --- -mavx256vnni       --- Use Intel Vector Neural Network Instructions 512 with 256bit operands
 # vnni512 = yes/no    --- -mavx512vnni       --- Use Intel Vector Neural Network Instructions 512
+# altivec = yes/no    --- -maltivec          --- Use PowerPC Altivec SIMD extension
+# vsx = yes/no        --- -mvsx              --- Use POWER VSX SIMD extension
 # neon = yes/no       --- -DUSE_NEON         --- Use ARM SIMD architecture
 # dotprod = yes/no    --- -DUSE_NEON_DOTPROD --- Use ARM advanced SIMD Int8 dot product instructions
+# lsx = yes/no        --- -mlsx              --- Use Loongson SIMD eXtension
+# lasx = yes/no       --- -mlasx             --- use Loongson Advanced SIMD eXtension
 #
 # Note that Makefile is space sensitive, so when adding new architectures
 # or modifying existing flags, you have to make sure there are no extra spaces
@@ -124,8 +129,9 @@ endif
 ifeq ($(ARCH), $(filter $(ARCH), \
                  x86-64-vnni512 x86-64-vnni256 x86-64-avx512 x86-64-avxvnni x86-64-bmi2 \
                  x86-64-avx2 x86-64-sse41-popcnt x86-64-modern x86-64-ssse3 x86-64-sse3-popcnt \
-                 x86-64 x86-32-sse41-popcnt x86-32-sse2 x86-32 ppc-64 ppc-32 e2k \
-                 armv7 armv7-neon armv8 armv8-dotprod apple-silicon general-64 general-32 riscv64 loongarch64))
+                 x86-64 x86-32-sse41-popcnt x86-32-sse2 x86-32 ppc-64 ppc-64-altivec ppc-64-vsx ppc-32 e2k \
+                 armv7 armv7-neon armv8 armv8-dotprod apple-silicon general-64 general-32 riscv64 \
+                 loongarch64 loongarch64-lsx loongarch64-lasx))
    SUPPORTED_ARCH=true
 else
    SUPPORTED_ARCH=false
@@ -148,9 +154,13 @@ avxvnni = no
 avx512 = no
 vnni256 = no
 vnni512 = no
+altivec = no
+vsx = no
 neon = no
 dotprod = no
 arm_version = 0
+lsx = no
+lasx = no
 STRIP = strip
 
 ifneq ($(shell which clang-format-18 2> /dev/null),)
@@ -355,6 +365,20 @@ ifeq ($(ARCH),ppc-64)
 	prefetch = yes
 endif
 
+ifeq ($(ARCH),ppc-64-altivec)
+	arch = ppc64
+	popcnt = yes
+	prefetch = yes
+	altivec = yes
+endif
+
+ifeq ($(ARCH),ppc-64-vsx)
+	arch = ppc64
+	popcnt = yes
+	prefetch = yes
+	vsx = yes
+endif
+
 ifeq ($(findstring e2k,$(ARCH)),e2k)
 	arch = e2k
 	mmx = yes
@@ -370,8 +394,19 @@ ifeq ($(ARCH),riscv64)
 	arch = riscv64
 endif
 
-ifeq ($(ARCH),loongarch64)
+ifeq ($(findstring loongarch64,$(ARCH)),loongarch64)
 	arch = loongarch64
+	prefetch = yes
+
+ifeq ($(findstring -lasx,$(ARCH)),-lasx)
+	lsx = yes
+	lasx = yes
+endif
+
+ifeq ($(findstring -lsx,$(ARCH)),-lsx)
+	lsx = yes
+endif
+
 endif
 endif
 
@@ -408,7 +443,7 @@ ifeq ($(COMP),gcc)
 		ifeq ($(ARCH),riscv64)
 			CXXFLAGS += -latomic
 		endif
-	else ifeq ($(ARCH),loongarch64)
+	else ifeq ($(arch),loongarch64)
 		CXXFLAGS += -latomic
 	else
 		CXXFLAGS += -m$(bits)
@@ -480,7 +515,7 @@ ifeq ($(COMP),clang)
 		ifeq ($(ARCH),riscv64)
 			CXXFLAGS += -latomic
 		endif
-	else ifeq ($(ARCH),loongarch64)
+	else ifeq ($(arch),loongarch64)
 		CXXFLAGS += -latomic
 	else
 		CXXFLAGS += -m$(bits)
@@ -634,7 +669,7 @@ else
 endif
 
 ifeq ($(popcnt),yes)
-	ifeq ($(arch),$(filter $(arch),ppc64 armv7 armv8 arm64))
+	ifeq ($(arch),$(filter $(arch),ppc64 ppc64-altivec ppc64-vsx armv7 armv8 arm64))
 		CXXFLAGS += -DUSE_POPCNT
 	else
 		CXXFLAGS += -msse3 -mpopcnt -DUSE_POPCNT
@@ -704,6 +739,20 @@ ifeq ($(mmx),yes)
 	endif
 endif
 
+ifeq ($(altivec),yes)
+	CXXFLAGS += -maltivec
+	ifeq ($(COMP),gcc)
+		CXXFLAGS += -mabi=altivec
+	endif
+endif
+
+ifeq ($(vsx),yes)
+	CXXFLAGS += -mvsx
+	ifeq ($(COMP),gcc)
+		CXXFLAGS += -DNO_WARN_X86_INTRINSICS -DUSE_SSE2
+	endif
+endif
+
 ifeq ($(neon),yes)
 	CXXFLAGS += -DUSE_NEON=$(arm_version)
 	ifeq ($(KERNEL),Linux)
@@ -719,6 +768,18 @@ ifeq ($(dotprod),yes)
 	CXXFLAGS += -march=armv8.2-a+dotprod -DUSE_NEON_DOTPROD
 endif
 
+ifeq ($(lasx),yes)
+	ifeq ($(comp),$(filter $(comp),gcc clang mingw icx))
+		CXXFLAGS += -mlasx
+	endif
+endif
+
+ifeq ($(lsx),yes)
+	ifeq ($(comp),$(filter $(comp),gcc clang mingw icx))
+		CXXFLAGS += -mlsx
+	endif
+endif
+
 ### 3.7 pext
 ifeq ($(pext),yes)
 	CXXFLAGS += -DUSE_PEXT
@@ -791,71 +852,75 @@ endif
 ### ==========================================================================
 
 help:
-	@echo ""
-	@echo "To compile stockfish, type: "
-	@echo ""
-	@echo "make -j target [ARCH=arch] [COMP=compiler] [COMPCXX=cxx]"
-	@echo ""
-	@echo "Supported targets:"
-	@echo ""
-	@echo "help                    > Display architecture details"
-	@echo "profile-build           > standard build with profile-guided optimization"
-	@echo "build                   > skip profile-guided optimization"
-	@echo "net                     > Download the default nnue nets"
-	@echo "strip                   > Strip executable"
-	@echo "install                 > Install executable"
-	@echo "clean                   > Clean up"
-	@echo ""
-	@echo "Supported archs:"
-	@echo ""
-	@echo "native                  > select the best architecture for the host processor (default)"
-	@echo "x86-64-vnni512          > x86 64-bit with vnni 512bit support"
-	@echo "x86-64-vnni256          > x86 64-bit with vnni 512bit support, limit operands to 256bit wide"
-	@echo "x86-64-avx512           > x86 64-bit with avx512 support"
-	@echo "x86-64-avxvnni          > x86 64-bit with vnni 256bit support"
-	@echo "x86-64-bmi2             > x86 64-bit with bmi2 support"
-	@echo "x86-64-avx2             > x86 64-bit with avx2 support"
-	@echo "x86-64-sse41-popcnt     > x86 64-bit with sse41 and popcnt support"
-	@echo "x86-64-modern           > deprecated, currently x86-64-sse41-popcnt"
-	@echo "x86-64-ssse3            > x86 64-bit with ssse3 support"
-	@echo "x86-64-sse3-popcnt      > x86 64-bit with sse3 compile and popcnt support"
-	@echo "x86-64                  > x86 64-bit generic (with sse2 support)"
-	@echo "x86-32-sse41-popcnt     > x86 32-bit with sse41 and popcnt support"
-	@echo "x86-32-sse2             > x86 32-bit with sse2 support"
-	@echo "x86-32                  > x86 32-bit generic (with mmx compile support)"
-	@echo "ppc-64                  > PPC 64-bit"
-	@echo "ppc-32                  > PPC 32-bit"
-	@echo "armv7                   > ARMv7 32-bit"
-	@echo "armv7-neon              > ARMv7 32-bit with popcnt and neon"
-	@echo "armv8                   > ARMv8 64-bit with popcnt and neon"
-	@echo "armv8-dotprod           > ARMv8 64-bit with popcnt, neon and dot product support"
-	@echo "e2k                     > Elbrus 2000"
-	@echo "apple-silicon           > Apple silicon ARM64"
-	@echo "general-64              > unspecified 64-bit"
-	@echo "general-32              > unspecified 32-bit"
-	@echo "riscv64                 > RISC-V 64-bit"
-	@echo "loongarch64             > LoongArch 64-bit"
-	@echo ""
-	@echo "Supported compilers:"
-	@echo ""
-	@echo "gcc                     > GNU compiler (default)"
-	@echo "mingw                   > GNU compiler with MinGW under Windows"
-	@echo "clang                   > LLVM Clang compiler"
-	@echo "icx                     > Intel oneAPI DPC++/C++ Compiler"
-	@echo "ndk                     > Google NDK to cross-compile for Android"
-	@echo ""
-	@echo "Simple examples. If you don't know what to do, you likely want to run one of: "
-	@echo ""
-	@echo "make -j profile-build ARCH=x86-64-avx2    # typically a fast compile for common systems "
-	@echo "make -j profile-build ARCH=x86-64-sse41-popcnt  # A more portable compile for 64-bit systems "
-	@echo "make -j profile-build ARCH=x86-64         # A portable compile for 64-bit systems "
-	@echo ""
-	@echo "Advanced examples, for experienced users: "
-	@echo ""
-	@echo "make -j profile-build ARCH=x86-64-avxvnni"
-	@echo "make -j profile-build ARCH=x86-64-avxvnni COMP=gcc COMPCXX=g++-12.0"
-	@echo "make -j build ARCH=x86-64-ssse3 COMP=clang"
-	@echo ""
+	@echo "" && \
+	echo "To compile stockfish, type: " && \
+	echo "" && \
+	echo "make -j target [ARCH=arch] [COMP=compiler] [COMPCXX=cxx]" && \
+	echo "" && \
+	echo "Supported targets:" && \
+	echo "" && \
+	echo "help                    > Display architecture details" && \
+	echo "profile-build           > standard build with profile-guided optimization" && \
+	echo "build                   > skip profile-guided optimization" && \
+	echo "net                     > Download the default nnue nets" && \
+	echo "strip                   > Strip executable" && \
+	echo "install                 > Install executable" && \
+	echo "clean                   > Clean up" && \
+	echo "" && \
+	echo "Supported archs:" && \
+	echo "" && \
+	echo "native                  > select the best architecture for the host processor (default)" && \
+	echo "x86-64-vnni512          > x86 64-bit with vnni 512bit support" && \
+	echo "x86-64-vnni256          > x86 64-bit with vnni 512bit support, limit operands to 256bit wide" && \
+	echo "x86-64-avx512           > x86 64-bit with avx512 support" && \
+	echo "x86-64-avxvnni          > x86 64-bit with vnni 256bit support" && \
+	echo "x86-64-bmi2             > x86 64-bit with bmi2 support" && \
+	echo "x86-64-avx2             > x86 64-bit with avx2 support" && \
+	echo "x86-64-sse41-popcnt     > x86 64-bit with sse41 and popcnt support" && \
+	echo "x86-64-modern           > deprecated, currently x86-64-sse41-popcnt" && \
+	echo "x86-64-ssse3            > x86 64-bit with ssse3 support" && \
+	echo "x86-64-sse3-popcnt      > x86 64-bit with sse3 compile and popcnt support" && \
+	echo "x86-64                  > x86 64-bit generic (with sse2 support)" && \
+	echo "x86-32-sse41-popcnt     > x86 32-bit with sse41 and popcnt support" && \
+	echo "x86-32-sse2             > x86 32-bit with sse2 support" && \
+	echo "x86-32                  > x86 32-bit generic (with mmx compile support)" && \
+	echo "ppc-64                  > PPC 64-bit" && \
+	echo "ppc-64-altivec          > PPC 64-bit with altivec support" && \
+	echo "ppc-64-vsx              > PPC 64-bit with vsx support" && \
+	echo "ppc-32                  > PPC 32-bit" && \
+	echo "armv7                   > ARMv7 32-bit" && \
+	echo "armv7-neon              > ARMv7 32-bit with popcnt and neon" && \
+	echo "armv8                   > ARMv8 64-bit with popcnt and neon" && \
+	echo "armv8-dotprod           > ARMv8 64-bit with popcnt, neon and dot product support" && \
+	echo "e2k                     > Elbrus 2000" && \
+	echo "apple-silicon           > Apple silicon ARM64" && \
+	echo "general-64              > unspecified 64-bit" && \
+	echo "general-32              > unspecified 32-bit" && \
+	echo "riscv64                 > RISC-V 64-bit" && \
+	echo "loongarch64             > LoongArch 64-bit" && \
+	echo "loongarch64-lsx         > LoongArch 64-bit with SIMD eXtension" && \
+	echo "loongarch64-lasx        > LoongArch 64-bit with Advanced SIMD eXtension" && \
+	echo "" && \
+	echo "Supported compilers:" && \
+	echo "" && \
+	echo "gcc                     > GNU compiler (default)" && \
+	echo "mingw                   > GNU compiler with MinGW under Windows" && \
+	echo "clang                   > LLVM Clang compiler" && \
+	echo "icx                     > Intel oneAPI DPC++/C++ Compiler" && \
+	echo "ndk                     > Google NDK to cross-compile for Android" && \
+	echo "" && \
+	echo "Simple examples. If you don't know what to do, you likely want to run one of: " && \
+	echo "" && \
+	echo "make -j profile-build ARCH=x86-64-avx2    # typically a fast compile for common systems " && \
+	echo "make -j profile-build ARCH=x86-64-sse41-popcnt  # A more portable compile for 64-bit systems " && \
+	echo "make -j profile-build ARCH=x86-64         # A portable compile for 64-bit systems " && \
+	echo "" && \
+	echo "Advanced examples, for experienced users: " && \
+	echo "" && \
+	echo "make -j profile-build ARCH=x86-64-avxvnni" && \
+	echo "make -j profile-build ARCH=x86-64-avxvnni COMP=gcc COMPCXX=g++-12.0" && \
+	echo "make -j build ARCH=x86-64-ssse3 COMP=clang" && \
+	echo ""
 ifneq ($(SUPPORTED_ARCH), true)
 	@echo "Specify a supported architecture with the ARCH option for more details"
 	@echo ""
@@ -917,59 +982,9 @@ profileclean:
 	@rm -f stockfish.res
 	@rm -f ./-lstdc++.res
 
-define fetch_network
-	@echo "Default net: $(nnuenet)"
-	@if [ "x$(curl_or_wget)" = "x" ]; then \
-		echo "Neither curl nor wget is installed. Install one of these tools unless the net has been downloaded manually"; \
-	fi
-	@if [ "x$(shasum_command)" = "x" ]; then \
-		echo "shasum / sha256sum not found, skipping net validation"; \
-	elif test -f "$(nnuenet)"; then \
-		if [ "$(nnuenet)" != "nn-"`$(shasum_command) $(nnuenet) | cut -c1-12`".nnue" ]; then \
-			echo "Removing invalid network"; rm -f $(nnuenet); \
-		fi; \
-	fi;
-	@for nnuedownloadurl in "$(nnuedownloadurl1)" "$(nnuedownloadurl2)"; do \
-		if test -f "$(nnuenet)"; then \
-			echo "$(nnuenet) available : OK"; break; \
-		else \
-			if [ "x$(curl_or_wget)" != "x" ]; then \
-				echo "Downloading $${nnuedownloadurl}"; $(curl_or_wget) $${nnuedownloadurl} > $(nnuenet);\
-			else \
-				echo "No net found and download not possible"; exit 1;\
-			fi; \
-		fi; \
-		if [ "x$(shasum_command)" != "x" ]; then \
-			if [ "$(nnuenet)" != "nn-"`$(shasum_command) $(nnuenet) | cut -c1-12`".nnue" ]; then \
-				echo "Removing failed download"; rm -f $(nnuenet); \
-			fi; \
-		fi; \
-	done
-	@if ! test -f "$(nnuenet)"; then \
-		echo "Failed to download $(nnuenet)."; \
-	fi;
-	@if [ "x$(shasum_command)" != "x" ]; then \
-		if [ "$(nnuenet)" = "nn-"`$(shasum_command) $(nnuenet) | cut -c1-12`".nnue" ]; then \
-			echo "Network validated"; break; \
-		fi; \
-	fi;
-endef
-
-# set up shell variables for the net stuff
-define netvariables
-$(eval nnuenet := $(shell grep $(1) evaluate.h | grep define | sed 's/.*\(nn-[a-z0-9]\{12\}.nnue\).*/\1/'))
-$(eval nnuedownloadurl1 := https://tests.stockfishchess.org/api/nn/$(nnuenet))
-$(eval nnuedownloadurl2 := https://github.com/official-stockfish/networks/raw/master/$(nnuenet))
-$(eval curl_or_wget := $(shell if hash curl 2>/dev/null; then echo "curl -skL"; elif hash wget 2>/dev/null; then echo "wget -qO-"; fi))
-$(eval shasum_command := $(shell if hash shasum 2>/dev/null; then echo "shasum -a 256 "; elif hash sha256sum 2>/dev/null; then echo "sha256sum "; fi))
-endef
-
 # evaluation network (nnue)
 net:
-	$(call netvariables, EvalFileDefaultNameBig)
-	$(call fetch_network)
-	$(call netvariables, EvalFileDefaultNameSmall)
-	$(call fetch_network)
+	@$(SHELL) ../scripts/net.sh
 
 format:
 	$(CLANG-FORMAT) -i $(SRCS) $(HEADERS) -style=file
@@ -986,61 +1001,71 @@ all: $(EXE) .depend
 
 config-sanity: net
 	@echo ""
-	@echo "Config:"
-	@echo "debug: '$(debug)'"
-	@echo "sanitize: '$(sanitize)'"
-	@echo "optimize: '$(optimize)'"
-	@echo "arch: '$(arch)'"
-	@echo "bits: '$(bits)'"
-	@echo "kernel: '$(KERNEL)'"
-	@echo "os: '$(OS)'"
-	@echo "prefetch: '$(prefetch)'"
-	@echo "popcnt: '$(popcnt)'"
-	@echo "pext: '$(pext)'"
-	@echo "sse: '$(sse)'"
-	@echo "mmx: '$(mmx)'"
-	@echo "sse2: '$(sse2)'"
-	@echo "ssse3: '$(ssse3)'"
-	@echo "sse41: '$(sse41)'"
-	@echo "avx2: '$(avx2)'"
-	@echo "avxvnni: '$(avxvnni)'"
-	@echo "avx512: '$(avx512)'"
-	@echo "vnni256: '$(vnni256)'"
-	@echo "vnni512: '$(vnni512)'"
-	@echo "neon: '$(neon)'"
-	@echo "dotprod: '$(dotprod)'"
-	@echo "arm_version: '$(arm_version)'"
-	@echo "target_windows: '$(target_windows)'"
-	@echo ""
-	@echo "Flags:"
-	@echo "CXX: $(CXX)"
-	@echo "CXXFLAGS: $(CXXFLAGS)"
-	@echo "LDFLAGS: $(LDFLAGS)"
-	@echo ""
-	@echo "Testing config sanity. If this fails, try 'make help' ..."
-	@echo ""
-	@test "$(debug)" = "yes" || test "$(debug)" = "no"
-	@test "$(optimize)" = "yes" || test "$(optimize)" = "no"
-	@test "$(SUPPORTED_ARCH)" = "true"
-	@test "$(arch)" = "any" || test "$(arch)" = "x86_64" || test "$(arch)" = "i386" || \
+	@echo "Config:" && \
+	echo "debug: '$(debug)'" && \
+	echo "sanitize: '$(sanitize)'" && \
+	echo "optimize: '$(optimize)'" && \
+	echo "arch: '$(arch)'" && \
+	echo "bits: '$(bits)'" && \
+	echo "kernel: '$(KERNEL)'" && \
+	echo "os: '$(OS)'" && \
+	echo "prefetch: '$(prefetch)'" && \
+	echo "popcnt: '$(popcnt)'" && \
+	echo "pext: '$(pext)'" && \
+	echo "sse: '$(sse)'" && \
+	echo "mmx: '$(mmx)'" && \
+	echo "sse2: '$(sse2)'" && \
+	echo "ssse3: '$(ssse3)'" && \
+	echo "sse41: '$(sse41)'" && \
+	echo "avx2: '$(avx2)'" && \
+	echo "avxvnni: '$(avxvnni)'" && \
+	echo "avx512: '$(avx512)'" && \
+	echo "vnni256: '$(vnni256)'" && \
+	echo "vnni512: '$(vnni512)'" && \
+	echo "altivec: '$(altivec)'" && \
+	echo "vsx: '$(vsx)'" && \
+	echo "neon: '$(neon)'" && \
+	echo "dotprod: '$(dotprod)'" && \
+	echo "arm_version: '$(arm_version)'" && \
+	echo "lsx: '$(lsx)'" && \
+	echo "lasx: '$(lasx)'" && \
+	echo "target_windows: '$(target_windows)'" && \
+	echo "" && \
+	echo "Flags:" && \
+	echo "CXX: $(CXX)" && \
+	echo "CXXFLAGS: $(CXXFLAGS)" && \
+	echo "LDFLAGS: $(LDFLAGS)" && \
+	echo "" && \
+	echo "Testing config sanity. If this fails, try 'make help' ..." && \
+	echo "" && \
+	(test "$(debug)" = "yes" || test "$(debug)" = "no") && \
+	(test "$(optimize)" = "yes" || test "$(optimize)" = "no") && \
+	(test "$(SUPPORTED_ARCH)" = "true") && \
+	(test "$(arch)" = "any" || test "$(arch)" = "x86_64" || test "$(arch)" = "i386" || \
 	 test "$(arch)" = "ppc64" || test "$(arch)" = "ppc" || test "$(arch)" = "e2k" || \
-	 test "$(arch)" = "armv7" || test "$(arch)" = "armv8" || test "$(arch)" = "arm64" || test "$(arch)" = "riscv64" || test "$(arch)" = "loongarch64"
-	@test "$(bits)" = "32" || test "$(bits)" = "64"
-	@test "$(prefetch)" = "yes" || test "$(prefetch)" = "no"
-	@test "$(popcnt)" = "yes" || test "$(popcnt)" = "no"
-	@test "$(pext)" = "yes" || test "$(pext)" = "no"
-	@test "$(sse)" = "yes" || test "$(sse)" = "no"
-	@test "$(mmx)" = "yes" || test "$(mmx)" = "no"
-	@test "$(sse2)" = "yes" || test "$(sse2)" = "no"
-	@test "$(ssse3)" = "yes" || test "$(ssse3)" = "no"
-	@test "$(sse41)" = "yes" || test "$(sse41)" = "no"
-	@test "$(avx2)" = "yes" || test "$(avx2)" = "no"
-	@test "$(avx512)" = "yes" || test "$(avx512)" = "no"
-	@test "$(vnni256)" = "yes" || test "$(vnni256)" = "no"
-	@test "$(vnni512)" = "yes" || test "$(vnni512)" = "no"
-	@test "$(neon)" = "yes" || test "$(neon)" = "no"
-	@test "$(comp)" = "gcc" || test "$(comp)" = "icx" || test "$(comp)" = "mingw" || test "$(comp)" = "clang" \
-	|| test "$(comp)" = "armv7a-linux-androideabi16-clang"  || test "$(comp)" = "aarch64-linux-android21-clang"
+	 test "$(arch)" = "armv7" || test "$(arch)" = "armv8" || test "$(arch)" = "arm64" || \
+	 test "$(arch)" = "riscv64" || test "$(arch)" = "loongarch64") && \
+	(test "$(bits)" = "32" || test "$(bits)" = "64") && \
+	(test "$(prefetch)" = "yes" || test "$(prefetch)" = "no") && \
+	(test "$(popcnt)" = "yes" || test "$(popcnt)" = "no") && \
+	(test "$(pext)" = "yes" || test "$(pext)" = "no") && \
+	(test "$(sse)" = "yes" || test "$(sse)" = "no") && \
+	(test "$(mmx)" = "yes" || test "$(mmx)" = "no") && \
+	(test "$(sse2)" = "yes" || test "$(sse2)" = "no") && \
+	(test "$(ssse3)" = "yes" || test "$(ssse3)" = "no") && \
+	(test "$(sse41)" = "yes" || test "$(sse41)" = "no") && \
+	(test "$(avx2)" = "yes" || test "$(avx2)" = "no") && \
+	(test "$(avx512)" = "yes" || test "$(avx512)" = "no") && \
+	(test "$(vnni256)" = "yes" || test "$(vnni256)" = "no") && \
+	(test "$(vnni512)" = "yes" || test "$(vnni512)" = "no") && \
+	(test "$(altivec)" = "yes" || test "$(altivec)" = "no") && \
+	(test "$(vsx)" = "yes" || test "$(vsx)" = "no") && \
+	(test "$(neon)" = "yes" || test "$(neon)" = "no") && \
+	(test "$(lsx)" = "yes" || test "$(lsx)" = "no") && \
+	(test "$(lasx)" = "yes" || test "$(lasx)" = "no") && \
+	(test "$(comp)" = "gcc" || test "$(comp)" = "icx" || test "$(comp)" = "mingw" || \
+	 test "$(comp)" = "clang" || test "$(comp)" = "armv7a-linux-androideabi16-clang" || \
+	 test "$(comp)" = "aarch64-linux-android21-clang")
 
 $(EXE): $(OBJS)
 	+$(CXX) -o $@ $(OBJS) $(LDFLAGS)

src/benchmark.cpp

@@ -1,6 +1,6 @@
 /*
   Stockfish, a UCI chess playing engine derived from Glaurung 2.1
-  Copyright (C) 2004-2024 The Stockfish developers (see AUTHORS file)
+  Copyright (C) 2004-2025 The Stockfish developers (see AUTHORS file)
 
   Stockfish is free software: you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
@@ -17,6 +17,7 @@
 */
 
 #include "benchmark.h"
+#include "numa.h"
 
 #include <cstdlib>
 #include <fstream>
@@ -91,6 +92,282 @@ const std::vector<std::string> Defaults = {
 };
 // clang-format on
 
+// clang-format off
+// human-randomly picked 5 games with <60 moves from
+// https://tests.stockfishchess.org/tests/view/665c71f9fd45fb0f907c21e0
+// only moves for one side
+const std::vector<std::vector<std::string>> BenchmarkPositions = {
+    {
+        "rnbq1k1r/ppp1bppp/4pn2/8/2B5/2NP1N2/PPP2PPP/R1BQR1K1 b - - 2 8",
+        "rnbq1k1r/pp2bppp/4pn2/2p5/2B2B2/2NP1N2/PPP2PPP/R2QR1K1 b - - 1 9",
+        "r1bq1k1r/pp2bppp/2n1pn2/2p5/2B1NB2/3P1N2/PPP2PPP/R2QR1K1 b - - 3 10",
+        "r1bq1k1r/pp2bppp/2n1p3/2p5/2B1PB2/5N2/PPP2PPP/R2QR1K1 b - - 0 11",
+        "r1b2k1r/pp2bppp/2n1p3/2p5/2B1PB2/5N2/PPP2PPP/3RR1K1 b - - 0 12",
+        "r1b1k2r/pp2bppp/2n1p3/2p5/2B1PB2/2P2N2/PP3PPP/3RR1K1 b - - 0 13",
+        "r1b1k2r/1p2bppp/p1n1p3/2p5/4PB2/2P2N2/PP2BPPP/3RR1K1 b - - 1 14",
+        "r1b1k2r/4bppp/p1n1p3/1pp5/P3PB2/2P2N2/1P2BPPP/3RR1K1 b - - 0 15",
+        "r1b1k2r/4bppp/p1n1p3/1P6/2p1PB2/2P2N2/1P2BPPP/3RR1K1 b - - 0 16",
+        "r1b1k2r/4bppp/2n1p3/1p6/2p1PB2/1PP2N2/4BPPP/3RR1K1 b - - 0 17",
+        "r3k2r/3bbppp/2n1p3/1p6/2P1PB2/2P2N2/4BPPP/3RR1K1 b - - 0 18",
+        "r3k2r/3bbppp/2n1p3/8/1pP1P3/2P2N2/3BBPPP/3RR1K1 b - - 1 19",
+        "1r2k2r/3bbppp/2n1p3/8/1pPNP3/2P5/3BBPPP/3RR1K1 b - - 3 20",
+        "1r2k2r/3bbppp/2n1p3/8/2PNP3/2B5/4BPPP/3RR1K1 b - - 0 21",
+        "1r2k2r/3bb1pp/2n1pp2/1N6/2P1P3/2B5/4BPPP/3RR1K1 b - - 1 22",
+        "1r2k2r/3b2pp/2n1pp2/1N6/1BP1P3/8/4BPPP/3RR1K1 b - - 0 23",
+        "1r2k2r/3b2pp/4pp2/1N6/1nP1P3/8/3RBPPP/4R1K1 b - - 1 24",
+        "1r5r/3bk1pp/4pp2/1N6/1nP1PP2/8/3RB1PP/4R1K1 b - - 0 25",
+        "1r5r/3bk1pp/2n1pp2/1N6/2P1PP2/8/3RBKPP/4R3 b - - 2 26",
+        "1r5r/3bk1pp/2n2p2/1N2p3/2P1PP2/6P1/3RBK1P/4R3 b - - 0 27",
+        "1r1r4/3bk1pp/2n2p2/1N2p3/2P1PP2/6P1/3RBK1P/R7 b - - 2 28",
+        "1r1r4/N3k1pp/2n1bp2/4p3/2P1PP2/6P1/3RBK1P/R7 b - - 4 29",
+        "1r1r4/3bk1pp/2N2p2/4p3/2P1PP2/6P1/3RBK1P/R7 b - - 0 30",
+        "1r1R4/4k1pp/2b2p2/4p3/2P1PP2/6P1/4BK1P/R7 b - - 0 31",
+        "3r4/4k1pp/2b2p2/4P3/2P1P3/6P1/4BK1P/R7 b - - 0 32",
+        "3r4/R3k1pp/2b5/4p3/2P1P3/6P1/4BK1P/8 b - - 1 33",
+        "8/3rk1pp/2b5/R3p3/2P1P3/6P1/4BK1P/8 b - - 3 34",
+        "8/3r2pp/2bk4/R1P1p3/4P3/6P1/4BK1P/8 b - - 0 35",
+        "8/2kr2pp/2b5/R1P1p3/4P3/4K1P1/4B2P/8 b - - 2 36",
+        "1k6/3r2pp/2b5/RBP1p3/4P3/4K1P1/7P/8 b - - 4 37",
+        "8/1k1r2pp/2b5/R1P1p3/4P3/3BK1P1/7P/8 b - - 6 38",
+        "1k6/3r2pp/2b5/2P1p3/4P3/3BK1P1/7P/R7 b - - 8 39",
+        "1k6/r5pp/2b5/2P1p3/4P3/3BK1P1/7P/5R2 b - - 10 40",
+        "1k3R2/6pp/2b5/2P1p3/4P3/r2BK1P1/7P/8 b - - 12 41",
+        "5R2/2k3pp/2b5/2P1p3/4P3/r2B2P1/3K3P/8 b - - 14 42",
+        "5R2/2k3pp/2b5/2P1p3/4P3/3BK1P1/r6P/8 b - - 16 43",
+        "5R2/2k3pp/2b5/2P1p3/4P3/r2B2P1/4K2P/8 b - - 18 44",
+        "5R2/2k3pp/2b5/2P1p3/4P3/3B1KP1/r6P/8 b - - 20 45",
+        "8/2k2Rpp/2b5/2P1p3/4P3/r2B1KP1/7P/8 b - - 22 46",
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+        "1r2q1k1/1R1n2p1/3rpp1p/1p6/1P2P3/5N1P/Q4PP1/R5K1 w - - 3 42",
+        "2r1q1k1/2Rn2p1/3rpp1p/1p6/1P2P3/5N1P/Q4PP1/R5K1 w - - 5 43",
+        "1r2q1k1/1R1n2p1/3rpp1p/1p6/1P2P3/5N1P/Q4PP1/R5K1 w - - 7 44",
+        "1rq3k1/R2n2p1/3rpp1p/1p6/1P2P3/5N1P/Q4PP1/R5K1 w - - 9 45",
+        "2q3k1/Rr1n2p1/3rpp1p/1p6/1P2P3/5N1P/4QPP1/R5K1 w - - 11 46",
+        "Rrq3k1/3n2p1/3rpp1p/1p6/1P2P3/5N1P/4QPP1/R5K1 w - - 13 47",
+    },
+    {
+        "rn1qkb1r/1pp2ppp/p4p2/3p1b2/5P2/1P2PN2/P1PP2PP/RN1QKB1R b KQkq - 1 6",
+        "r2qkb1r/1pp2ppp/p1n2p2/3p1b2/3P1P2/1P2PN2/P1P3PP/RN1QKB1R b KQkq - 0 7",
+        "r2qkb1r/1pp2ppp/p4p2/3p1b2/1n1P1P2/1P1BPN2/P1P3PP/RN1QK2R b KQkq - 2 8",
+        "r2qkb1r/1pp2ppp/p4p2/3p1b2/3P1P2/1P1PPN2/P5PP/RN1QK2R b KQkq - 0 9",
+        "r2qk2r/1pp2ppp/p2b1p2/3p1b2/3P1P2/1PNPPN2/P5PP/R2QK2R b KQkq - 2 10",
+        "r2qk2r/1p3ppp/p1pb1p2/3p1b2/3P1P2/1PNPPN2/P5PP/R2Q1RK1 b kq - 1 11",
+        "r2q1rk1/1p3ppp/p1pb1p2/3p1b2/3P1P2/1PNPPN2/P2Q2PP/R4RK1 b - - 3 12",
+        "r2qr1k1/1p3ppp/p1pb1p2/3p1b2/3P1P2/1P1PPN2/P2QN1PP/R4RK1 b - - 5 13",
+        "r3r1k1/1p3ppp/pqpb1p2/3p1b2/3P1P2/1P1PPNN1/P2Q2PP/R4RK1 b - - 7 14",
+        "r3r1k1/1p3ppp/pqp2p2/3p1b2/1b1P1P2/1P1PPNN1/P1Q3PP/R4RK1 b - - 9 15",
+        "r3r1k1/1p1b1ppp/pqp2p2/3p4/1b1P1P2/1P1PPNN1/P4QPP/R4RK1 b - - 11 16",
+        "2r1r1k1/1p1b1ppp/pqp2p2/3p4/1b1PPP2/1P1P1NN1/P4QPP/R4RK1 b - - 0 17",
+        "2r1r1k1/1p1b1ppp/pq3p2/2pp4/1b1PPP2/PP1P1NN1/5QPP/R4RK1 b - - 0 18",
+        "2r1r1k1/1p1b1ppp/pq3p2/2Pp4/4PP2/PPbP1NN1/5QPP/R4RK1 b - - 0 19",
+        "2r1r1k1/1p1b1ppp/p4p2/2Pp4/4PP2/PqbP1NN1/5QPP/RR4K1 b - - 1 20",
+        "2r1r1k1/1p1b1ppp/p4p2/2Pp4/q3PP2/P1bP1NN1/R4QPP/1R4K1 b - - 3 21",
+        "2r1r1k1/1p3ppp/p4p2/1bPP4/q4P2/P1bP1NN1/R4QPP/1R4K1 b - - 0 22",
+        "2r1r1k1/1p3ppp/p4p2/2PP4/q4P2/P1bb1NN1/R4QPP/2R3K1 b - - 1 23",
+        "2r1r1k1/1p3ppp/p2P1p2/2P5/2q2P2/P1bb1NN1/R4QPP/2R3K1 b - - 0 24",
+        "2rr2k1/1p3ppp/p2P1p2/2P5/2q2P2/P1bb1NN1/R4QPP/2R4K b - - 2 25",
+        "2rr2k1/1p3ppp/p2P1p2/2Q5/5P2/P1bb1NN1/R5PP/2R4K b - - 0 26",
+        "3r2k1/1p3ppp/p2P1p2/2r5/5P2/P1bb1N2/R3N1PP/2R4K b - - 1 27",
+        "3r2k1/1p3ppp/p2P1p2/2r5/5P2/P1b2N2/4R1PP/2R4K b - - 0 28",
+        "3r2k1/1p3ppp/p2P1p2/2r5/1b3P2/P4N2/4R1PP/3R3K b - - 2 29",
+        "3r2k1/1p2Rppp/p2P1p2/b1r5/5P2/P4N2/6PP/3R3K b - - 4 30",
+        "3r2k1/1R3ppp/p1rP1p2/b7/5P2/P4N2/6PP/3R3K b - - 0 31",
+        "3r2k1/1R3ppp/p2R1p2/b7/5P2/P4N2/6PP/7K b - - 0 32",
+        "6k1/1R3ppp/p2r1p2/b7/5P2/P4NP1/7P/7K b - - 0 33",
+        "6k1/1R3p1p/p2r1pp1/b7/5P1P/P4NP1/8/7K b - - 0 34",
+        "6k1/3R1p1p/pr3pp1/b7/5P1P/P4NP1/8/7K b - - 2 35",
+        "6k1/5p2/pr3pp1/b2R3p/5P1P/P4NP1/8/7K b - - 1 36",
+        "6k1/5p2/pr3pp1/7p/5P1P/P1bR1NP1/8/7K b - - 3 37",
+        "6k1/5p2/p1r2pp1/7p/5P1P/P1bR1NP1/6K1/8 b - - 5 38",
+        "6k1/5p2/p1r2pp1/b2R3p/5P1P/P4NP1/6K1/8 b - - 7 39",
+        "6k1/5p2/p4pp1/b2R3p/5P1P/P4NPK/2r5/8 b - - 9 40",
+        "6k1/2b2p2/p4pp1/7p/5P1P/P2R1NPK/2r5/8 b - - 11 41",
+        "6k1/2b2p2/5pp1/p6p/3N1P1P/P2R2PK/2r5/8 b - - 1 42",
+        "6k1/2b2p2/5pp1/p6p/3N1P1P/P1R3PK/r7/8 b - - 3 43",
+        "6k1/5p2/1b3pp1/p6p/5P1P/P1R3PK/r1N5/8 b - - 5 44",
+        "8/5pk1/1bR2pp1/p6p/5P1P/P5PK/r1N5/8 b - - 7 45",
+        "3b4/5pk1/2R2pp1/p4P1p/7P/P5PK/r1N5/8 b - - 0 46",
+        "8/4bpk1/2R2pp1/p4P1p/6PP/P6K/r1N5/8 b - - 0 47",
+        "8/5pk1/2R2pP1/p6p/6PP/b6K/r1N5/8 b - - 0 48",
+        "8/6k1/2R2pp1/p6P/7P/b6K/r1N5/8 b - - 0 49",
+        "8/6k1/2R2p2/p6p/7P/b5K1/r1N5/8 b - - 1 50",
+        "8/8/2R2pk1/p6p/7P/b4K2/r1N5/8 b - - 3 51",
+        "8/8/2R2pk1/p6p/7P/4NK2/rb6/8 b - - 5 52",
+        "2R5/8/5pk1/7p/p6P/4NK2/rb6/8 b - - 1 53",
+        "6R1/8/5pk1/7p/p6P/4NK2/1b6/r7 b - - 3 54",
+        "R7/5k2/5p2/7p/p6P/4NK2/1b6/r7 b - - 5 55",
+        "R7/5k2/5p2/7p/7P/p3N3/1b2K3/r7 b - - 1 56",
+        "8/R4k2/5p2/7p/7P/p3N3/1b2K3/7r b - - 3 57",
+        "8/8/5pk1/7p/R6P/p3N3/1b2K3/7r b - - 5 58",
+        "8/8/5pk1/7p/R6P/p7/4K3/2bN3r b - - 7 59",
+        "8/8/5pk1/7p/R6P/p7/4KN1r/2b5 b - - 9 60",
+        "8/8/5pk1/7p/R6P/p3K3/1b3N1r/8 b - - 11 61",
+        "8/8/R4pk1/7p/7P/p1b1K3/5N1r/8 b - - 13 62",
+        "8/8/5pk1/7p/7P/2b1K3/R4N1r/8 b - - 0 63",
+        "8/8/5pk1/7p/3K3P/8/R4N1r/4b3 b - - 2 64",
+    }
+};
+// clang-format on
+
 }  // namespace
 
 namespace Stockfish::Benchmark {
@@ -160,4 +437,76 @@ std::vector<std::string> setup_bench(const std::string& currentFen, std::istream
     return list;
 }
 
+BenchmarkSetup setup_benchmark(std::istream& is) {
+    // TT_SIZE_PER_THREAD is chosen such that roughly half of the hash is used all positions
+    // for the current sequence have been searched.
+    static constexpr int TT_SIZE_PER_THREAD = 128;
+
+    static constexpr int DEFAULT_DURATION_S = 150;
+
+    BenchmarkSetup setup{};
+
+    // Assign default values to missing arguments
+    int desiredTimeS;
+
+    if (!(is >> setup.threads))
+        setup.threads = get_hardware_concurrency();
+    else
+        setup.originalInvocation += std::to_string(setup.threads);
+
+    if (!(is >> setup.ttSize))
+        setup.ttSize = TT_SIZE_PER_THREAD * setup.threads;
+    else
+        setup.originalInvocation += " " + std::to_string(setup.ttSize);
+
+    if (!(is >> desiredTimeS))
+        desiredTimeS = DEFAULT_DURATION_S;
+    else
+        setup.originalInvocation += " " + std::to_string(desiredTimeS);
+
+    setup.filledInvocation += std::to_string(setup.threads) + " " + std::to_string(setup.ttSize)
+                            + " " + std::to_string(desiredTimeS);
+
+    auto getCorrectedTime = [&](int ply) {
+        // time per move is fit roughly based on LTC games
+        // seconds = 50/{ply+15}
+        // ms = 50000/{ply+15}
+        // with this fit 10th move gets 2000ms
+        // adjust for desired 10th move time
+        return 50000.0 / (static_cast<double>(ply) + 15.0);
+    };
+
+    float totalTime = 0;
+    for (const auto& game : BenchmarkPositions)
+    {
+        setup.commands.emplace_back("ucinewgame");
+        int ply = 1;
+        for (int i = 0; i < static_cast<int>(game.size()); ++i)
+        {
+            const float correctedTime = getCorrectedTime(ply);
+            totalTime += correctedTime;
+            ply += 1;
+        }
+    }
+
+    float timeScaleFactor = static_cast<float>(desiredTimeS * 1000) / totalTime;
+
+    for (const auto& game : BenchmarkPositions)
+    {
+        setup.commands.emplace_back("ucinewgame");
+        int ply = 1;
+        for (const std::string& fen : game)
+        {
+            setup.commands.emplace_back("position fen " + fen);
+
+            const int correctedTime = static_cast<int>(getCorrectedTime(ply) * timeScaleFactor);
+            setup.commands.emplace_back("go movetime " + std::to_string(correctedTime));
+
+            ply += 1;
+        }
+    }
+
+    return setup;
+}
+
 }  // namespace Stockfish

src/benchmark.h

@@ -1,6 +1,6 @@
 /*
   Stockfish, a UCI chess playing engine derived from Glaurung 2.1
-  Copyright (C) 2004-2024 The Stockfish developers (see AUTHORS file)
+  Copyright (C) 2004-2025 The Stockfish developers (see AUTHORS file)
 
   Stockfish is free software: you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
@@ -27,6 +27,16 @@ namespace Stockfish::Benchmark {
 
 std::vector<std::string> setup_bench(const std::string&, std::istream&);
 
+struct BenchmarkSetup {
+    int                      ttSize;
+    int                      threads;
+    std::vector<std::string> commands;
+    std::string              originalInvocation;
+    std::string              filledInvocation;
+};
+
+BenchmarkSetup setup_benchmark(std::istream&);
+
 }  // namespace Stockfish
 
 #endif  // #ifndef BENCHMARK_H_INCLUDED

src/bitboard.cpp

@@ -1,6 +1,6 @@
 /*
   Stockfish, a UCI chess playing engine derived from Glaurung 2.1
-  Copyright (C) 2004-2024 The Stockfish developers (see AUTHORS file)
+  Copyright (C) 2004-2025 The Stockfish developers (see AUTHORS file)
 
   Stockfish is free software: you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
@@ -34,15 +34,14 @@ Bitboard BetweenBB[SQUARE_NB][SQUARE_NB];
 Bitboard PseudoAttacks[PIECE_TYPE_NB][SQUARE_NB];
 Bitboard PawnAttacks[COLOR_NB][SQUARE_NB];
 
-Magic RookMagics[SQUARE_NB];
-Magic BishopMagics[SQUARE_NB];
+alignas(64) Magic Magics[SQUARE_NB][2];
 
 namespace {
 
 Bitboard RookTable[0x19000];   // To store rook attacks
 Bitboard BishopTable[0x1480];  // To store bishop attacks
 
-void init_magics(PieceType pt, Bitboard table[], Magic magics[]);
+void init_magics(PieceType pt, Bitboard table[], Magic magics[][2]);
 
 // Returns the bitboard of target square for the given step
 // from the given square. If the step is off the board, returns empty bitboard.
@@ -82,8 +81,8 @@ void Bitboards::init() {
         for (Square s2 = SQ_A1; s2 <= SQ_H8; ++s2)
             SquareDistance[s1][s2] = std::max(distance<File>(s1, s2), distance<Rank>(s1, s2));
 
-    init_magics(ROOK, RookTable, RookMagics);
-    init_magics(BISHOP, BishopTable, BishopMagics);
+    init_magics(ROOK, RookTable, Magics);
+    init_magics(BISHOP, BishopTable, Magics);
 
     for (Square s1 = SQ_A1; s1 <= SQ_H8; ++s1)
     {
@@ -140,41 +139,49 @@ Bitboard sliding_attack(PieceType pt, Square sq, Bitboard occupied) {
 
 // Computes all rook and bishop attacks at startup. Magic
 // bitboards are used to look up attacks of sliding pieces. As a reference see
-// www.chessprogramming.org/Magic_Bitboards. In particular, here we use the so
-// called "fancy" approach.
-void init_magics(PieceType pt, Bitboard table[], Magic magics[]) {
+// https://www.chessprogramming.org/Magic_Bitboards. In particular, here we use
+// the so called "fancy" approach.
+void init_magics(PieceType pt, Bitboard table[], Magic magics[][2]) {
 
+#ifndef USE_PEXT
     // Optimal PRNG seeds to pick the correct magics in the shortest time
     int seeds[][RANK_NB] = {{8977, 44560, 54343, 38998, 5731, 95205, 104912, 17020},
                             {728, 10316, 55013, 32803, 12281, 15100, 16645, 255}};
 
-    Bitboard occupancy[4096], reference[4096], edges, b;
-    int      epoch[4096] = {}, cnt = 0, size = 0;
+    Bitboard occupancy[4096];
+    int      epoch[4096] = {}, cnt = 0;
+#endif
+    Bitboard reference[4096];
+    int      size = 0;
 
     for (Square s = SQ_A1; s <= SQ_H8; ++s)
     {
         // Board edges are not considered in the relevant occupancies
-        edges = ((Rank1BB | Rank8BB) & ~rank_bb(s)) | ((FileABB | FileHBB) & ~file_bb(s));
+        Bitboard edges = ((Rank1BB | Rank8BB) & ~rank_bb(s)) | ((FileABB | FileHBB) & ~file_bb(s));
 
         // Given a square 's', the mask is the bitboard of sliding attacks from
         // 's' computed on an empty board. The index must be big enough to contain
         // all the attacks for each possible subset of the mask and so is 2 power
         // the number of 1s of the mask. Hence we deduce the size of the shift to
         // apply to the 64 or 32 bits word to get the index.
-        Magic& m = magics[s];
+        Magic& m = magics[s][pt - BISHOP];
         m.mask   = sliding_attack(pt, s, 0) & ~edges;
-        m.shift  = (Is64Bit ? 64 : 32) - popcount(m.mask);
-
+#ifndef USE_PEXT
+        m.shift = (Is64Bit ? 64 : 32) - popcount(m.mask);
+#endif
         // Set the offset for the attacks table of the square. We have individual
         // table sizes for each square with "Fancy Magic Bitboards".
-        m.attacks = s == SQ_A1 ? table : magics[s - 1].attacks + size;
+        m.attacks = s == SQ_A1 ? table : magics[s - 1][pt - BISHOP].attacks + size;
+        size      = 0;
 
         // Use Carry-Rippler trick to enumerate all subsets of masks[s] and
         // store the corresponding sliding attack bitboard in reference[].
-        b = size = 0;
+        Bitboard b = 0;
         do
         {
+#ifndef USE_PEXT
             occupancy[size] = b;
+#endif
             reference[size] = sliding_attack(pt, s, b);
 
             if (HasPext)
@@ -184,9 +191,7 @@ void init_magics(PieceType pt, Bitboard table[], Magic magics[]) {
             b = (b - m.mask) & m.mask;
         } while (b);
 
-        if (HasPext)
-            continue;
-
+#ifndef USE_PEXT
         PRNG rng(seeds[Is64Bit][rank_of(s)]);
 
         // Find a magic for square 's' picking up an (almost) random number
@@ -215,6 +220,7 @@ void init_magics(PieceType pt, Bitboard table[], Magic magics[]) {
                     break;
             }
         }
+#endif
     }
 }
 }

src/bitboard.h

@@ -1,6 +1,6 @@
 /*
   Stockfish, a UCI chess playing engine derived from Glaurung 2.1
-  Copyright (C) 2004-2024 The Stockfish developers (see AUTHORS file)
+  Copyright (C) 2004-2025 The Stockfish developers (see AUTHORS file)
 
   Stockfish is free software: you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
@@ -22,6 +22,7 @@
 #include <algorithm>
 #include <cassert>
 #include <cmath>
+#include <cstring>
 #include <cstdint>
 #include <cstdlib>
 #include <string>
@@ -67,27 +68,31 @@ extern Bitboard PawnAttacks[COLOR_NB][SQUARE_NB];
 // Magic holds all magic bitboards relevant data for a single square
 struct Magic {
     Bitboard  mask;
-    Bitboard  magic;
     Bitboard* attacks;
-    unsigned  shift;
+#ifndef USE_PEXT
+    Bitboard magic;
+    unsigned shift;
+#endif
 
     // Compute the attack's index using the 'magic bitboards' approach
     unsigned index(Bitboard occupied) const {
 
-        if (HasPext)
-            return unsigned(pext(occupied, mask));
-
+#ifdef USE_PEXT
+        return unsigned(pext(occupied, mask));
+#else
         if (Is64Bit)
             return unsigned(((occupied & mask) * magic) >> shift);
 
         unsigned lo = unsigned(occupied) & unsigned(mask);
         unsigned hi = unsigned(occupied >> 32) & unsigned(mask >> 32);
         return (lo * unsigned(magic) ^ hi * unsigned(magic >> 32)) >> shift;
+#endif
     }
+
+    Bitboard attacks_bb(Bitboard occupied) const { return attacks[index(occupied)]; }
 };
 
-extern Magic RookMagics[SQUARE_NB];
-extern Magic BishopMagics[SQUARE_NB];
+extern Magic Magics[SQUARE_NB][2];
 
 constexpr Bitboard square_bb(Square s) {
     assert(is_ok(s));
@@ -229,9 +234,8 @@ inline Bitboard attacks_bb(Square s, Bitboard occupied) {
     switch (Pt)
     {
     case BISHOP :
-        return BishopMagics[s].attacks[BishopMagics[s].index(occupied)];
     case ROOK :
-        return RookMagics[s].attacks[RookMagics[s].index(occupied)];
+        return Magics[s][Pt - BISHOP].attacks_bb(occupied);
     case QUEEN :
         return attacks_bb<BISHOP>(s, occupied) | attacks_bb<ROOK>(s, occupied);
     default :
@@ -265,11 +269,10 @@ inline int popcount(Bitboard b) {
 
 #ifndef USE_POPCNT
 
-    union {
-        Bitboard bb;
-        uint16_t u[4];
-    } v = {b};
-    return PopCnt16[v.u[0]] + PopCnt16[v.u[1]] + PopCnt16[v.u[2]] + PopCnt16[v.u[3]];
+    std::uint16_t indices[4];
+    std::memcpy(indices, &b, sizeof(b));
+    return PopCnt16[indices[0]] + PopCnt16[indices[1]] + PopCnt16[indices[2]]
+         + PopCnt16[indices[3]];
 
 #elif defined(_MSC_VER)
 

src/engine.cpp

@@ -1,6 +1,6 @@
 /*
   Stockfish, a UCI chess playing engine derived from Glaurung 2.1
-  Copyright (C) 2004-2024 The Stockfish developers (see AUTHORS file)
+  Copyright (C) 2004-2025 The Stockfish developers (see AUTHORS file)
 
   Stockfish is free software: you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
@@ -18,6 +18,7 @@
 
 #include "engine.h"
 
+#include <algorithm>
 #include <cassert>
 #include <deque>
 #include <iosfwd>
@@ -32,6 +33,7 @@
 #include "misc.h"
 #include "nnue/network.h"
 #include "nnue/nnue_common.h"
+#include "numa.h"
 #include "perft.h"
 #include "position.h"
 #include "search.h"
@@ -44,11 +46,12 @@ namespace Stockfish {
 
 namespace NN = Eval::NNUE;
 
-constexpr auto StartFEN  = "rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR w KQkq - 0 1";
-constexpr int  MaxHashMB = Is64Bit ? 33554432 : 2048;
+constexpr auto StartFEN   = "rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR w KQkq - 0 1";
+constexpr int  MaxHashMB  = Is64Bit ? 33554432 : 2048;
+int            MaxThreads = std::max(1024, 4 * int(get_hardware_concurrency()));
 
-Engine::Engine(std::string path) :
-    binaryDirectory(CommandLine::get_binary_directory(path)),
+Engine::Engine(std::optional<std::string> path) :
+    binaryDirectory(path ? CommandLine::get_binary_directory(*path) : ""),
     numaContext(NumaConfig::from_system()),
     states(new std::deque<StateInfo>(1)),
     threads(),
@@ -58,58 +61,84 @@ Engine::Engine(std::string path) :
         NN::NetworkBig({EvalFileDefaultNameBig, "None", ""}, NN::EmbeddedNNUEType::BIG),
         NN::NetworkSmall({EvalFileDefaultNameSmall, "None", ""}, NN::EmbeddedNNUEType::SMALL))) {
     pos.set(StartFEN, false, &states->back());
-    capSq = SQ_NONE;
 
-    options["Debug Log File"] << Option("", [](const Option& o) {
-        start_logger(o);
-        return std::nullopt;
-    });
 
-    options["NumaPolicy"] << Option("auto", [this](const Option& o) {
-        set_numa_config_from_option(o);
-        return numa_config_information_as_string() + "\n" + thread_binding_information_as_string();
-    });
+    options.add(  //
+      "Debug Log File", Option("", [](const Option& o) {
+          start_logger(o);
+          return std::nullopt;
+      }));
 
-    options["Threads"] << Option(1, 1, 1024, [this](const Option&) {
-        resize_threads();
-        return thread_binding_information_as_string();
-    });
+    options.add(  //
+      "NumaPolicy", Option("auto", [this](const Option& o) {
+          set_numa_config_from_option(o);
+          return numa_config_information_as_string() + "\n"
+               + thread_allocation_information_as_string();
+      }));
 
-    options["Hash"] << Option(16, 1, MaxHashMB, [this](const Option& o) {
-        set_tt_size(o);
-        return std::nullopt;
-    });
+    options.add(  //
+      "Threads", Option(1, 1, MaxThreads, [this](const Option&) {
+          resize_threads();
+          return thread_allocation_information_as_string();
+      }));
 
-    options["Clear Hash"] << Option([this](const Option&) {
-        search_clear();
-        return std::nullopt;
-    });
-    options["Ponder"] << Option(false);
-    options["MultiPV"] << Option(1, 1, MAX_MOVES);
-    options["Skill Level"] << Option(20, 0, 20);
-    options["Move Overhead"] << Option(10, 0, 5000);
-    options["nodestime"] << Option(0, 0, 10000);
-    options["UCI_Chess960"] << Option(false);
-    options["UCI_LimitStrength"] << Option(false);
-    options["UCI_Elo"] << Option(Stockfish::Search::Skill::LowestElo,
-                                 Stockfish::Search::Skill::LowestElo,
-                                 Stockfish::Search::Skill::HighestElo);
-    options["UCI_ShowWDL"] << Option(false);
-    options["SyzygyPath"] << Option("", [](const Option& o) {
-        Tablebases::init(o);
-        return std::nullopt;
-    });
-    options["SyzygyProbeDepth"] << Option(1, 1, 100);
-    options["Syzygy50MoveRule"] << Option(true);
-    options["SyzygyProbeLimit"] << Option(7, 0, 7);
-    options["EvalFile"] << Option(EvalFileDefaultNameBig, [this](const Option& o) {
-        load_big_network(o);
-        return std::nullopt;
-    });
-    options["EvalFileSmall"] << Option(EvalFileDefaultNameSmall, [this](const Option& o) {
-        load_small_network(o);
-        return std::nullopt;
-    });
+    options.add(  //
+      "Hash", Option(16, 1, MaxHashMB, [this](const Option& o) {
+          set_tt_size(o);
+          return std::nullopt;
+      }));
+
+    options.add(  //
+      "Clear Hash", Option([this](const Option&) {
+          search_clear();
+          return std::nullopt;
+      }));
+
+    options.add(  //
+      "Ponder", Option(false));
+
+    options.add(  //
+      "MultiPV", Option(1, 1, MAX_MOVES));
+
+    options.add("Skill Level", Option(20, 0, 20));
+
+    options.add("Move Overhead", Option(10, 0, 5000));
+
+    options.add("nodestime", Option(0, 0, 10000));
+
+    options.add("UCI_Chess960", Option(false));
+
+    options.add("UCI_LimitStrength", Option(false));
+
+    options.add("UCI_Elo",
+                Option(Stockfish::Search::Skill::LowestElo, Stockfish::Search::Skill::LowestElo,
+                       Stockfish::Search::Skill::HighestElo));
+
+    options.add("UCI_ShowWDL", Option(false));
+
+    options.add(  //
+      "SyzygyPath", Option("", [](const Option& o) {
+          Tablebases::init(o);
+          return std::nullopt;
+      }));
+
+    options.add("SyzygyProbeDepth", Option(1, 1, 100));
+
+    options.add("Syzygy50MoveRule", Option(true));
+
+    options.add("SyzygyProbeLimit", Option(7, 0, 7));
+
+    options.add(  //
+      "EvalFile", Option(EvalFileDefaultNameBig, [this](const Option& o) {
+          load_big_network(o);
+          return std::nullopt;
+      }));
+
+    options.add(  //
+      "EvalFileSmall", Option(EvalFileDefaultNameSmall, [this](const Option& o) {
+          load_small_network(o);
+          return std::nullopt;
+      }));
 
     load_networks();
     resize_threads();
@@ -124,7 +153,6 @@ std::uint64_t Engine::perft(const std::string& fen, Depth depth, bool isChess960
 void Engine::go(Search::LimitsType& limits) {
     assert(limits.perft == 0);
     verify_networks();
-    limits.capSq = capSq;
 
     threads.start_thinking(options, pos, states, limits);
 }
@@ -156,6 +184,10 @@ void Engine::set_on_bestmove(std::function<void(std::string_view, std::string_vi
     updateContext.onBestmove = std::move(f);
 }
 
+void Engine::set_on_verify_networks(std::function<void(std::string_view)>&& f) {
+    onVerifyNetworks = std::move(f);
+}
+
 void Engine::wait_for_search_finished() { threads.main_thread()->wait_for_search_finished(); }
 
 void Engine::set_position(const std::string& fen, const std::vector<std::string>& moves) {
@@ -163,7 +195,6 @@ void Engine::set_position(const std::string& fen, const std::vector<std::string>
     states = StateListPtr(new std::deque<StateInfo>(1));
     pos.set(fen, options["UCI_Chess960"], &states->back());
 
-    capSq = SQ_NONE;
     for (const auto& move : moves)
     {
         auto m = UCIEngine::to_move(pos, move);
@@ -173,11 +204,6 @@ void Engine::set_position(const std::string& fen, const std::vector<std::string>
 
         states->emplace_back();
         pos.do_move(m, states->back());
-
-        capSq          = SQ_NONE;
-        DirtyPiece& dp = states->back().dirtyPiece;
-        if (dp.dirty_num > 1 && dp.to[1] == SQ_NONE)
-            capSq = m.to_sq();
     }
 }
 
@@ -226,8 +252,8 @@ void Engine::set_ponderhit(bool b) { threads.main_manager()->ponder = b; }
 // network related
 
 void Engine::verify_networks() const {
-    networks->big.verify(options["EvalFile"]);
-    networks->small.verify(options["EvalFileSmall"]);
+    networks->big.verify(options["EvalFile"], onVerifyNetworks);
+    networks->small.verify(options["EvalFileSmall"], onVerifyNetworks);
 }
 
 void Engine::load_networks() {
@@ -285,6 +311,8 @@ std::string Engine::visualize() const {
     return ss.str();
 }
 
+int Engine::get_hashfull(int maxAge) const { return tt.hashfull(maxAge); }
+
 std::vector<std::pair<size_t, size_t>> Engine::get_bound_thread_count_by_numa_node() const {
     auto                                   counts = threads.get_bound_thread_count_by_numa_node();
     const NumaConfig&                      cfg    = numaContext.get_numa_config();
@@ -310,15 +338,9 @@ std::string Engine::numa_config_information_as_string() const {
 std::string Engine::thread_binding_information_as_string() const {
     auto              boundThreadsByNode = get_bound_thread_count_by_numa_node();
     std::stringstream ss;
-
-    size_t threadsSize = threads.size();
-    ss << "Using " << threadsSize << (threadsSize > 1 ? " threads" : " thread");
-
     if (boundThreadsByNode.empty())
         return ss.str();
 
-    ss << " with NUMA node thread binding: ";
-
     bool isFirst = true;
 
     for (auto&& [current, total] : boundThreadsByNode)
@@ -332,4 +354,19 @@ std::string Engine::thread_binding_information_as_string() const {
     return ss.str();
 }
 
+std::string Engine::thread_allocation_information_as_string() const {
+    std::stringstream ss;
+
+    size_t threadsSize = threads.size();
+    ss << "Using " << threadsSize << (threadsSize > 1 ? " threads" : " thread");
+
+    auto boundThreadsByNodeStr = thread_binding_information_as_string();
+    if (boundThreadsByNodeStr.empty())
+        return ss.str();
+
+    ss << " with NUMA node thread binding: ";
+    ss << boundThreadsByNodeStr;
+
+    return ss.str();
+}
 }

src/engine.h

@@ -1,6 +1,6 @@
 /*
   Stockfish, a UCI chess playing engine derived from Glaurung 2.1
-  Copyright (C) 2004-2024 The Stockfish developers (see AUTHORS file)
+  Copyright (C) 2004-2025 The Stockfish developers (see AUTHORS file)
 
   Stockfish is free software: you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
@@ -39,15 +39,13 @@
 
 namespace Stockfish {
 
-enum Square : int;
-
 class Engine {
    public:
     using InfoShort = Search::InfoShort;
     using InfoFull  = Search::InfoFull;
     using InfoIter  = Search::InfoIteration;
 
-    Engine(std::string path = "");
+    Engine(std::optional<std::string> path = std::nullopt);
 
     // Cannot be movable due to components holding backreferences to fields
     Engine(const Engine&)            = delete;
@@ -81,6 +79,7 @@ class Engine {
     void set_on_update_full(std::function<void(const InfoFull&)>&&);
     void set_on_iter(std::function<void(const InfoIter&)>&&);
     void set_on_bestmove(std::function<void(std::string_view, std::string_view)>&&);
+    void set_on_verify_networks(std::function<void(std::string_view)>&&);
 
     // network related
 
@@ -97,12 +96,15 @@ class Engine {
     const OptionsMap& get_options() const;
     OptionsMap&       get_options();
 
+    int get_hashfull(int maxAge = 0) const;
+
     std::string                            fen() const;
     void                                   flip();
     std::string                            visualize() const;
     std::vector<std::pair<size_t, size_t>> get_bound_thread_count_by_numa_node() const;
     std::string                            get_numa_config_as_string() const;
     std::string                            numa_config_information_as_string() const;
+    std::string                            thread_allocation_information_as_string() const;
     std::string                            thread_binding_information_as_string() const;
 
    private:
@@ -112,14 +114,14 @@ class Engine {
 
     Position     pos;
     StateListPtr states;
-    Square       capSq;
 
     OptionsMap                               options;
     ThreadPool                               threads;
     TranspositionTable                       tt;
     LazyNumaReplicated<Eval::NNUE::Networks> networks;
 
-    Search::SearchManager::UpdateContext updateContext;
+    Search::SearchManager::UpdateContext  updateContext;
+    std::function<void(std::string_view)> onVerifyNetworks;
 };
 
 }  // namespace Stockfish

src/evaluate.cpp

@@ -1,6 +1,6 @@
 /*
   Stockfish, a UCI chess playing engine derived from Glaurung 2.1
-  Copyright (C) 2004-2024 The Stockfish developers (see AUTHORS file)
+  Copyright (C) 2004-2025 The Stockfish developers (see AUTHORS file)
 
   Stockfish is free software: you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
@@ -54,37 +54,33 @@ bool Eval::use_smallnet(const Position& pos) {
 // of the position from the point of view of the side to move.
 Value Eval::evaluate(const Eval::NNUE::Networks&    networks,
                      const Position&                pos,
+                     Eval::NNUE::AccumulatorStack&  accumulators,
                      Eval::NNUE::AccumulatorCaches& caches,
                      int                            optimism) {
 
     assert(!pos.checkers());
 
-    bool smallNet = use_smallnet(pos);
-    int  v;
-
-    auto [psqt, positional] = smallNet ? networks.small.evaluate(pos, &caches.small)
-                                       : networks.big.evaluate(pos, &caches.big);
+    bool smallNet           = use_smallnet(pos);
+    auto [psqt, positional] = smallNet ? networks.small.evaluate(pos, accumulators, &caches.small)
+                                       : networks.big.evaluate(pos, accumulators, &caches.big);
 
     Value nnue = (125 * psqt + 131 * positional) / 128;
 
     // Re-evaluate the position when higher eval accuracy is worth the time spent
-    if (smallNet && (nnue * psqt < 0 || std::abs(nnue) < 227))
+    if (smallNet && (std::abs(nnue) < 236))
     {
-        std::tie(psqt, positional) = networks.big.evaluate(pos, &caches.big);
+        std::tie(psqt, positional) = networks.big.evaluate(pos, accumulators, &caches.big);
         nnue                       = (125 * psqt + 131 * positional) / 128;
         smallNet                   = false;
     }
 
     // Blend optimism and eval with nnue complexity
     int nnueComplexity = std::abs(psqt - positional);
-    optimism += optimism * nnueComplexity / (smallNet ? 433 : 453);
-    nnue -= nnue * nnueComplexity / (smallNet ? 18815 : 17864);
+    optimism += optimism * nnueComplexity / 468;
+    nnue -= nnue * nnueComplexity / 18000;
 
-    int material = (smallNet ? 553 : 532) * pos.count<PAWN>() + pos.non_pawn_material();
-    v = (nnue * (73921 + material) + optimism * (8112 + material)) / (smallNet ? 68104 : 74715);
-
-    // Evaluation grain (to get more alpha-beta cuts) with randomization (for robustness)
-    v = (v / 16) * 16 - 1 + (pos.key() & 0x2);
+    int material = 535 * pos.count<PAWN>() + pos.non_pawn_material();
+    int v        = (nnue * (77777 + material) + optimism * (7777 + material)) / 77777;
 
     // Damp down the evaluation linearly when shuffling
     v -= v * pos.rule50_count() / 212;
@@ -104,7 +100,10 @@ std::string Eval::trace(Position& pos, const Eval::NNUE::Networks& networks) {
     if (pos.checkers())
         return "Final evaluation: none (in check)";
 
-    auto caches = std::make_unique<Eval::NNUE::AccumulatorCaches>(networks);
+    Eval::NNUE::AccumulatorStack accumulators;
+    auto                         caches = std::make_unique<Eval::NNUE::AccumulatorCaches>(networks);
+
+    accumulators.reset(pos, networks, *caches);
 
     std::stringstream ss;
     ss << std::showpoint << std::noshowpos << std::fixed << std::setprecision(2);
@@ -112,12 +111,12 @@ std::string Eval::trace(Position& pos, const Eval::NNUE::Networks& networks) {
 
     ss << std::showpoint << std::showpos << std::fixed << std::setprecision(2) << std::setw(15);
 
-    auto [psqt, positional] = networks.big.evaluate(pos, &caches->big);
+    auto [psqt, positional] = networks.big.evaluate(pos, accumulators, &caches->big);
     Value v                 = psqt + positional;
     v                       = pos.side_to_move() == WHITE ? v : -v;
     ss << "NNUE evaluation        " << 0.01 * UCIEngine::to_cp(v, pos) << " (white side)\n";
 
-    v = evaluate(networks, pos, *caches, VALUE_ZERO);
+    v = evaluate(networks, pos, accumulators, *caches, VALUE_ZERO);
     v = pos.side_to_move() == WHITE ? v : -v;
     ss << "Final evaluation       " << 0.01 * UCIEngine::to_cp(v, pos) << " (white side)";
     ss << " [with scaled NNUE, ...]";

src/evaluate.h

@@ -1,6 +1,6 @@
 /*
   Stockfish, a UCI chess playing engine derived from Glaurung 2.1
-  Copyright (C) 2004-2024 The Stockfish developers (see AUTHORS file)
+  Copyright (C) 2004-2025 The Stockfish developers (see AUTHORS file)
 
   Stockfish is free software: you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
@@ -33,12 +33,13 @@ namespace Eval {
 // for the build process (profile-build and fishtest) to work. Do not change the
 // name of the macro or the location where this macro is defined, as it is used
 // in the Makefile/Fishtest.
-#define EvalFileDefaultNameBig "nn-1111cefa1111.nnue"
+#define EvalFileDefaultNameBig "nn-1c0000000000.nnue"
 #define EvalFileDefaultNameSmall "nn-37f18f62d772.nnue"
 
 namespace NNUE {
 struct Networks;
 struct AccumulatorCaches;
+class AccumulatorStack;
 }
 
 std::string trace(Position& pos, const Eval::NNUE::Networks& networks);
@@ -47,6 +48,7 @@ int   simple_eval(const Position& pos, Color c);
 bool  use_smallnet(const Position& pos);
 Value evaluate(const NNUE::Networks&          networks,
                const Position&                pos,
+               Eval::NNUE::AccumulatorStack&  accumulators,
                Eval::NNUE::AccumulatorCaches& caches,
                int                            optimism);
 }  // namespace Eval

src/history.h

@@ -0,0 +1,171 @@
+/*
+  Stockfish, a UCI chess playing engine derived from Glaurung 2.1
+  Copyright (C) 2004-2025 The Stockfish developers (see AUTHORS file)
+
+  Stockfish is free software: you can redistribute it and/or modify
+  it under the terms of the GNU General Public License as published by
+  the Free Software Foundation, either version 3 of the License, or
+  (at your option) any later version.
+
+  Stockfish is distributed in the hope that it will be useful,
+  but WITHOUT ANY WARRANTY; without even the implied warranty of
+  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+  GNU General Public License for more details.
+
+  You should have received a copy of the GNU General Public License
+  along with this program.  If not, see <http://www.gnu.org/licenses/>.
+*/
+
+#ifndef HISTORY_H_INCLUDED
+#define HISTORY_H_INCLUDED
+
+#include <algorithm>
+#include <array>
+#include <cassert>
+#include <cmath>
+#include <cstdint>
+#include <cstdlib>
+#include <limits>
+#include <type_traits>  // IWYU pragma: keep
+
+#include "misc.h"
+#include "position.h"
+
+namespace Stockfish {
+
+constexpr int PAWN_HISTORY_SIZE        = 512;    // has to be a power of 2
+constexpr int CORRECTION_HISTORY_SIZE  = 32768;  // has to be a power of 2
+constexpr int CORRECTION_HISTORY_LIMIT = 1024;
+constexpr int LOW_PLY_HISTORY_SIZE     = 4;
+
+static_assert((PAWN_HISTORY_SIZE & (PAWN_HISTORY_SIZE - 1)) == 0,
+              "PAWN_HISTORY_SIZE has to be a power of 2");
+
+static_assert((CORRECTION_HISTORY_SIZE & (CORRECTION_HISTORY_SIZE - 1)) == 0,
+              "CORRECTION_HISTORY_SIZE has to be a power of 2");
+
+enum PawnHistoryType {
+    Normal,
+    Correction
+};
+
+template<PawnHistoryType T = Normal>
+inline int pawn_structure_index(const Position& pos) {
+    return pos.pawn_key() & ((T == Normal ? PAWN_HISTORY_SIZE : CORRECTION_HISTORY_SIZE) - 1);
+}
+
+inline int minor_piece_index(const Position& pos) {
+    return pos.minor_piece_key() & (CORRECTION_HISTORY_SIZE - 1);
+}
+
+template<Color c>
+inline int non_pawn_index(const Position& pos) {
+    return pos.non_pawn_key(c) & (CORRECTION_HISTORY_SIZE - 1);
+}
+
+// StatsEntry is the container of various numerical statistics. We use a class
+// instead of a naked value to directly call history update operator<<() on
+// the entry. The first template parameter T is the base type of the array,
+// and the second template parameter D limits the range of updates in [-D, D]
+// when we update values with the << operator
+template<typename T, int D>
+class StatsEntry {
+
+    static_assert(std::is_arithmetic_v<T>, "Not an arithmetic type");
+    static_assert(D <= std::numeric_limits<T>::max(), "D overflows T");
+
+    T entry;
+
+   public:
+    StatsEntry& operator=(const T& v) {
+        entry = v;
+        return *this;
+    }
+    operator const T&() const { return entry; }
+
+    void operator<<(int bonus) {
+        // Make sure that bonus is in range [-D, D]
+        int clampedBonus = std::clamp(bonus, -D, D);
+        entry += clampedBonus - entry * std::abs(clampedBonus) / D;
+
+        assert(std::abs(entry) <= D);
+    }
+};
+
+enum StatsType {
+    NoCaptures,
+    Captures
+};
+
+template<typename T, int D, std::size_t... Sizes>
+using Stats = MultiArray<StatsEntry<T, D>, Sizes...>;
+
+// ButterflyHistory records how often quiet moves have been successful or unsuccessful
+// during the current search, and is used for reduction and move ordering decisions.
+// It uses 2 tables (one for each color) indexed by the move's from and to squares,
+// see https://www.chessprogramming.org/Butterfly_Boards (~11 elo)
+using ButterflyHistory = Stats<std::int16_t, 7183, COLOR_NB, int(SQUARE_NB) * int(SQUARE_NB)>;
+
+// LowPlyHistory is adressed by play and move's from and to squares, used
+// to improve move ordering near the root
+using LowPlyHistory =
+  Stats<std::int16_t, 7183, LOW_PLY_HISTORY_SIZE, int(SQUARE_NB) * int(SQUARE_NB)>;
+
+// CapturePieceToHistory is addressed by a move's [piece][to][captured piece type]
+using CapturePieceToHistory = Stats<std::int16_t, 10692, PIECE_NB, SQUARE_NB, PIECE_TYPE_NB>;
+
+// PieceToHistory is like ButterflyHistory but is addressed by a move's [piece][to]
+using PieceToHistory = Stats<std::int16_t, 30000, PIECE_NB, SQUARE_NB>;
+
+// ContinuationHistory is the combined history of a given pair of moves, usually
+// the current one given a previous one. The nested history table is based on
+// PieceToHistory instead of ButterflyBoards.
+// (~63 elo)
+using ContinuationHistory = MultiArray<PieceToHistory, PIECE_NB, SQUARE_NB>;
+
+// PawnHistory is addressed by the pawn structure and a move's [piece][to]
+using PawnHistory = Stats<std::int16_t, 8192, PAWN_HISTORY_SIZE, PIECE_NB, SQUARE_NB>;
+
+// Correction histories record differences between the static evaluation of
+// positions and their search score. It is used to improve the static evaluation
+// used by some search heuristics.
+// see https://www.chessprogramming.org/Static_Evaluation_Correction_History
+enum CorrHistType {
+    Pawn,          // By color and pawn structure
+    Minor,         // By color and positions of minor pieces (Knight, Bishop)
+    NonPawn,       // By non-pawn material positions and color
+    PieceTo,       // By [piece][to] move
+    Continuation,  // Combined history of move pairs
+};
+
+namespace Detail {
+
+template<CorrHistType>
+struct CorrHistTypedef {
+    using type = Stats<std::int16_t, CORRECTION_HISTORY_LIMIT, CORRECTION_HISTORY_SIZE, COLOR_NB>;
+};
+
+template<>
+struct CorrHistTypedef<PieceTo> {
+    using type = Stats<std::int16_t, CORRECTION_HISTORY_LIMIT, PIECE_NB, SQUARE_NB>;
+};
+
+template<>
+struct CorrHistTypedef<Continuation> {
+    using type = MultiArray<CorrHistTypedef<PieceTo>::type, PIECE_NB, SQUARE_NB>;
+};
+
+template<>
+struct CorrHistTypedef<NonPawn> {
+    using type =
+      Stats<std::int16_t, CORRECTION_HISTORY_LIMIT, CORRECTION_HISTORY_SIZE, COLOR_NB, COLOR_NB>;
+};
+
+}
+
+template<CorrHistType T>
+using CorrectionHistory = typename Detail::CorrHistTypedef<T>::type;
+
+}  // namespace Stockfish
+
+#endif  // #ifndef HISTORY_H_INCLUDED

src/incbin/incbin.h

@@ -3,8 +3,8 @@
  * @author Dale Weiler
  * @brief Utility for including binary files
  *
- * Facilities for including binary files into the current translation unit
- * and making use of them externally in other translation units.
+ * Facilities for including binary files into the current translation unit and
+ * making use from them externally in other translation units.
  */
 #ifndef INCBIN_HDR
 #define INCBIN_HDR
@@ -26,7 +26,9 @@
       defined(__SSSE3__)    || \
       defined(__SSE4_1__)   || \
       defined(__SSE4_2__)   || \
-      defined(__neon__)
+      defined(__neon__)     || \
+      defined(__ARM_NEON)   || \
+      defined(__ALTIVEC__)
 # define INCBIN_ALIGNMENT_INDEX 4
 #elif ULONG_MAX != 0xffffffffu
 # define INCBIN_ALIGNMENT_INDEX 3
@@ -64,6 +66,9 @@
     X
 #define INCBIN_INVOKE(N, ...) \
     INCBIN_EVAL(N(__VA_ARGS__))
+/* Variable argument count for overloading by arity */
+#define INCBIN_VA_ARG_COUNTER(_1, _2, _3, N, ...) N
+#define INCBIN_VA_ARGC(...) INCBIN_VA_ARG_COUNTER(__VA_ARGS__, 3, 2, 1, 0)
 
 /* Green Hills uses a different directive for including binary data */
 #if defined(__ghs__)
@@ -117,29 +122,50 @@
 #endif
 
 /**
- * @brief Optionally override the linker section into which data is emitted.
- *
- * @warning If you use this facility, you'll have to deal with platform-specific linker output
- * section naming on your own
- *
- * Overriding the default linker output section, e.g for esp8266/Arduino:
- * @code
- * #define INCBIN_OUTPUT_SECTION ".irom.text"
- * #include "incbin.h"
- * INCBIN(Foo, "foo.txt");
- * // Data is emitted into program memory that never gets copied to RAM
- * @endcode
+ * @brief Optionally override the linker section into which size and data is
+ * emitted.
+ * 
+ * @warning If you use this facility, you might have to deal with
+ * platform-specific linker output section naming on your own.
  */
 #if !defined(INCBIN_OUTPUT_SECTION)
 #  if defined(__APPLE__)
-#    define INCBIN_OUTPUT_SECTION         ".const_data"
+#    define INCBIN_OUTPUT_SECTION ".const_data"
 #  else
-#    define INCBIN_OUTPUT_SECTION         ".rodata"
+#    define INCBIN_OUTPUT_SECTION ".rodata"
 #  endif
 #endif
 
+/**
+ * @brief Optionally override the linker section into which data is emitted.
+ *
+ * @warning If you use this facility, you might have to deal with
+ * platform-specific linker output section naming on your own.
+ */
+#if !defined(INCBIN_OUTPUT_DATA_SECTION)
+#  define INCBIN_OUTPUT_DATA_SECTION INCBIN_OUTPUT_SECTION
+#endif
+
+/**
+ * @brief Optionally override the linker section into which size is emitted.
+ *
+ * @warning If you use this facility, you might have to deal with
+ * platform-specific linker output section naming on your own.
+ * 
+ * @note This is useful for Harvard architectures where program memory cannot
+ * be directly read from the program without special instructions. With this you
+ * can chose to put the size variable in RAM rather than ROM.
+ */
+#if !defined(INCBIN_OUTPUT_SIZE_SECTION)
+#  define INCBIN_OUTPUT_SIZE_SECTION INCBIN_OUTPUT_SECTION
+#endif
+
 #if defined(__APPLE__)
-/* The directives are different for Apple-branded compilers */
+#  include "TargetConditionals.h"
+#  if defined(TARGET_OS_IPHONE) && !defined(INCBIN_SILENCE_BITCODE_WARNING)
+#    warning "incbin is incompatible with bitcode. Using the library will break upload to App Store if you have bitcode enabled. Add `#define INCBIN_SILENCE_BITCODE_WARNING` before including this header to silence this warning."
+#  endif
+/* The directives are different for Apple branded compilers */
 #  define INCBIN_SECTION         INCBIN_OUTPUT_SECTION "\n"
 #  define INCBIN_GLOBAL(NAME)    ".globl " INCBIN_MANGLE INCBIN_STRINGIZE(INCBIN_PREFIX) #NAME "\n"
 #  define INCBIN_INT             ".long "
@@ -179,27 +205,17 @@
 /**
  * @brief Specify the prefix to use for symbol names.
  *
- * By default this is `g', producing symbols of the form:
- * @code
- * #include "incbin.h"
- * INCBIN(Foo, "foo.txt");
+ * @note By default this is "g".
  *
- * // Now you have the following symbols:
- * // const unsigned char gFooData[];
- * // const unsigned char *const gFooEnd;
- * // const unsigned int gFooSize;
- * @endcode
- *
- * If however you specify a prefix before including: e.g:
  * @code
  * #define INCBIN_PREFIX incbin
  * #include "incbin.h"
  * INCBIN(Foo, "foo.txt");
  *
  * // Now you have the following symbols instead:
- * // const unsigned char incbinFooData[];
- * // const unsigned char *const incbinFooEnd;
- * // const unsigned int incbinFooSize;
+ * // const unsigned char incbinFoo<data>[];
+ * // const unsigned char *const incbinFoo<end>;
+ * // const unsigned int incbinFoo<size>;
  * @endcode
  */
 #if !defined(INCBIN_PREFIX)
@@ -213,18 +229,8 @@
  * - INCBIN_STYLE_CAMEL "CamelCase"
  * - INCBIN_STYLE_SNAKE "snake_case"
  *
- * Default option is *INCBIN_STYLE_CAMEL* producing symbols of the form:
- * @code
- * #include "incbin.h"
- * INCBIN(Foo, "foo.txt");
+ * @note By default this is INCBIN_STYLE_CAMEL
  *
- * // Now you have the following symbols:
- * // const unsigned char <prefix>FooData[];
- * // const unsigned char *const <prefix>FooEnd;
- * // const unsigned int <prefix>FooSize;
- * @endcode
- *
- * If however you specify a style before including: e.g:
  * @code
  * #define INCBIN_STYLE INCBIN_STYLE_SNAKE
  * #include "incbin.h"
@@ -261,8 +267,8 @@
     INCBIN_STRINGIZE( \
         INCBIN_STYLE_IDENT(TYPE)) \
 
-/* Generate the global labels by indirectly invoking the macro
- * with our style type and concatenate the name against them. */
+/* Generate the global labels by indirectly invoking the macro with our style
+ * type and concatenating the name against them. */
 #define INCBIN_GLOBAL_LABELS(NAME, TYPE) \
     INCBIN_INVOKE( \
         INCBIN_GLOBAL, \
@@ -288,23 +294,38 @@
  * The symbol names are a concatenation of `INCBIN_PREFIX' before *NAME*; with
  * "Data", as well as "End" and "Size" after. An example is provided below.
  *
+ * @param TYPE Optional array type. Omitting this picks a default of `unsigned char`.
  * @param NAME The name given for the binary data
  *
  * @code
  * INCBIN_EXTERN(Foo);
  *
  * // Now you have the following symbols:
- * // extern const unsigned char <prefix>FooData[];
- * // extern const unsigned char *const <prefix>FooEnd;
- * // extern const unsigned int <prefix>FooSize;
+ * // extern const unsigned char <prefix>Foo<data>[];
+ * // extern const unsigned char *const <prefix>Foo<end>;
+ * // extern const unsigned int <prefix>Foo<size>;
+ * @endcode
+ * 
+ * You may specify a custom optional data type as well as the first argument.
+ * @code
+ * INCBIN_EXTERN(custom_type, Foo);
+ * 
+ * // Now you have the following symbols:
+ * // extern const custom_type <prefix>Foo<data>[];
+ * // extern const custom_type *const <prefix>Foo<end>;
+ * // extern const unsigned int <prefix>Foo<size>;
  * @endcode
  */
-#define INCBIN_EXTERN(NAME) \
-    INCBIN_EXTERNAL const INCBIN_ALIGN unsigned char \
+#define INCBIN_EXTERN(...) \
+    INCBIN_CONCATENATE(INCBIN_EXTERN_, INCBIN_VA_ARGC(__VA_ARGS__))(__VA_ARGS__)
+#define INCBIN_EXTERN_1(NAME, ...) \
+    INCBIN_EXTERN_2(unsigned char, NAME)
+#define INCBIN_EXTERN_2(TYPE, NAME) \
+    INCBIN_EXTERNAL const INCBIN_ALIGN TYPE \
         INCBIN_CONCATENATE( \
             INCBIN_CONCATENATE(INCBIN_PREFIX, NAME), \
             INCBIN_STYLE_IDENT(DATA))[]; \
-    INCBIN_EXTERNAL const INCBIN_ALIGN unsigned char *const \
+    INCBIN_EXTERNAL const INCBIN_ALIGN TYPE *const \
     INCBIN_CONCATENATE( \
         INCBIN_CONCATENATE(INCBIN_PREFIX, NAME), \
         INCBIN_STYLE_IDENT(END)); \
@@ -313,6 +334,29 @@
             INCBIN_CONCATENATE(INCBIN_PREFIX, NAME), \
             INCBIN_STYLE_IDENT(SIZE))
 
+/**
+ * @brief Externally reference textual data included in another translation unit.
+ *
+ * Produces three external symbols that reference the textual data included in
+ * another translation unit.
+ *
+ * The symbol names are a concatenation of `INCBIN_PREFIX' before *NAME*; with
+ * "Data", as well as "End" and "Size" after. An example is provided below.
+ *
+ * @param NAME The name given for the textual data
+ *
+ * @code
+ * INCBIN_EXTERN(Foo);
+ *
+ * // Now you have the following symbols:
+ * // extern const char <prefix>Foo<data>[];
+ * // extern const char *const <prefix>Foo<end>;
+ * // extern const unsigned int <prefix>Foo<size>;
+ * @endcode
+ */
+#define INCTXT_EXTERN(NAME) \
+    INCBIN_EXTERN_2(char, NAME)
+
 /**
  * @brief Include a binary file into the current translation unit.
  *
@@ -322,6 +366,7 @@
  * The symbol names are a concatenation of `INCBIN_PREFIX' before *NAME*; with
  * "Data", as well as "End" and "Size" after. An example is provided below.
  *
+ * @param TYPE Optional array type. Omitting this picks a default of `unsigned char`.
  * @param NAME The name to associate with this binary data (as an identifier.)
  * @param FILENAME The file to include (as a string literal.)
  *
@@ -329,9 +374,20 @@
  * INCBIN(Icon, "icon.png");
  *
  * // Now you have the following symbols:
- * // const unsigned char <prefix>IconData[];
- * // const unsigned char *const <prefix>IconEnd;
- * // const unsigned int <prefix>IconSize;
+ * // const unsigned char <prefix>Icon<data>[];
+ * // const unsigned char *const <prefix>Icon<end>;
+ * // const unsigned int <prefix>Icon<size>;
+ * @endcode
+ * 
+ * You may specify a custom optional data type as well as the first argument.
+ * These macros are specialized by arity.
+ * @code
+ * INCBIN(custom_type, Icon, "icon.png");
+ *
+ * // Now you have the following symbols:
+ * // const custom_type <prefix>Icon<data>[];
+ * // const custom_type *const <prefix>Icon<end>;
+ * // const unsigned int <prefix>Icon<size>;
  * @endcode
  *
  * @warning This must be used in global scope
@@ -341,15 +397,28 @@
  * please @see INCBIN_EXTERN.
  */
 #ifdef _MSC_VER
-#define INCBIN(NAME, FILENAME) \
-    INCBIN_EXTERN(NAME)
+#  define INCBIN(NAME, FILENAME) \
+      INCBIN_EXTERN(NAME)
 #else
-#define INCBIN(NAME, FILENAME) \
+#  define INCBIN(...) \
+     INCBIN_CONCATENATE(INCBIN_, INCBIN_VA_ARGC(__VA_ARGS__))(__VA_ARGS__)
+#  if defined(__GNUC__)
+#    define INCBIN_1(...) _Pragma("GCC error \"Single argument INCBIN not allowed\"")
+#  elif defined(__clang__)
+#    define INCBIN_1(...) _Pragma("clang error \"Single argument INCBIN not allowed\"")
+#  else
+#    define INCBIN_1(...) /* Cannot do anything here */
+#  endif
+#  define INCBIN_2(NAME, FILENAME) \
+      INCBIN_3(unsigned char, NAME, FILENAME)
+#  define INCBIN_3(TYPE, NAME, FILENAME) INCBIN_COMMON(TYPE, NAME, FILENAME, /* No terminator for binary data */)
+#  define INCBIN_COMMON(TYPE, NAME, FILENAME, TERMINATOR) \
     __asm__(INCBIN_SECTION \
             INCBIN_GLOBAL_LABELS(NAME, DATA) \
             INCBIN_ALIGN_HOST \
             INCBIN_MANGLE INCBIN_STRINGIZE(INCBIN_PREFIX) #NAME INCBIN_STYLE_STRING(DATA) ":\n" \
             INCBIN_MACRO " \"" FILENAME "\"\n" \
+                TERMINATOR \
             INCBIN_GLOBAL_LABELS(NAME, END) \
             INCBIN_ALIGN_BYTE \
             INCBIN_MANGLE INCBIN_STRINGIZE(INCBIN_PREFIX) #NAME INCBIN_STYLE_STRING(END) ":\n" \
@@ -362,7 +431,46 @@
             INCBIN_ALIGN_HOST \
             ".text\n" \
     ); \
-    INCBIN_EXTERN(NAME)
+    INCBIN_EXTERN(TYPE, NAME)
+#endif
 
+/**
+ * @brief Include a textual file into the current translation unit.
+ * 
+ * This behaves the same as INCBIN except it produces char compatible arrays
+ * and implicitly adds a null-terminator byte, thus the size of data included
+ * by this is one byte larger than that of INCBIN.
+ *
+ * Includes a textual file into the current translation unit, producing three
+ * symbols for objects that encode the data and size respectively.
+ *
+ * The symbol names are a concatenation of `INCBIN_PREFIX' before *NAME*; with
+ * "Data", as well as "End" and "Size" after. An example is provided below.
+ *
+ * @param NAME The name to associate with this binary data (as an identifier.)
+ * @param FILENAME The file to include (as a string literal.)
+ *
+ * @code
+ * INCTXT(Readme, "readme.txt");
+ *
+ * // Now you have the following symbols:
+ * // const char <prefix>Readme<data>[];
+ * // const char *const <prefix>Readme<end>;
+ * // const unsigned int <prefix>Readme<size>;
+ * @endcode
+ *
+ * @warning This must be used in global scope
+ * @warning The identifiers may be different if INCBIN_STYLE is not default
+ *
+ * To externally reference the data included by this in another translation unit
+ * please @see INCBIN_EXTERN.
+ */
+#if defined(_MSC_VER)
+#  define INCTXT(NAME, FILENAME) \
+     INCBIN_EXTERN(NAME)
+#else
+#  define INCTXT(NAME, FILENAME) \
+     INCBIN_COMMON(char, NAME, FILENAME, INCBIN_BYTE "0\n")
 #endif
-#endif
+
+#endif

src/main.cpp

@@ -1,6 +1,6 @@
 /*
   Stockfish, a UCI chess playing engine derived from Glaurung 2.1
-  Copyright (C) 2004-2024 The Stockfish developers (see AUTHORS file)
+  Copyright (C) 2004-2025 The Stockfish developers (see AUTHORS file)
 
   Stockfish is free software: you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by

src/memory.cpp

@@ -1,6 +1,6 @@
 /*
   Stockfish, a UCI chess playing engine derived from Glaurung 2.1
-  Copyright (C) 2004-2024 The Stockfish developers (see AUTHORS file)
+  Copyright (C) 2004-2025 The Stockfish developers (see AUTHORS file)
 
   Stockfish is free software: you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
@@ -212,6 +212,37 @@ void* aligned_large_pages_alloc(size_t allocSize) {
 
 #endif
 
+bool has_large_pages() {
+
+#if defined(_WIN32)
+
+    constexpr size_t page_size = 2 * 1024 * 1024;  // 2MB page size assumed
+    void*            mem       = aligned_large_pages_alloc_windows(page_size);
+    if (mem == nullptr)
+    {
+        return false;
+    }
+    else
+    {
+        aligned_large_pages_free(mem);
+        return true;
+    }
+
+#elif defined(__linux__)
+
+    #if defined(MADV_HUGEPAGE)
+    return true;
+    #else
+    return false;
+    #endif
+
+#else
+
+    return false;
+
+#endif
+}
+
 
 // aligned_large_pages_free() will free the previously memory allocated
 // by aligned_large_pages_alloc(). The effect is a nop if mem == nullptr.

src/memory.h

@@ -1,6 +1,6 @@
 /*
   Stockfish, a UCI chess playing engine derived from Glaurung 2.1
-  Copyright (C) 2004-2024 The Stockfish developers (see AUTHORS file)
+  Copyright (C) 2004-2025 The Stockfish developers (see AUTHORS file)
 
   Stockfish is free software: you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
@@ -38,6 +38,8 @@ void  std_aligned_free(void* ptr);
 void* aligned_large_pages_alloc(size_t size);
 void  aligned_large_pages_free(void* mem);
 
+bool has_large_pages();
+
 // Frees memory which was placed there with placement new.
 // Works for both single objects and arrays of unknown bound.
 template<typename T, typename FREE_FUNC>

src/misc.cpp

@@ -1,6 +1,6 @@
 /*
   Stockfish, a UCI chess playing engine derived from Glaurung 2.1
-  Copyright (C) 2004-2024 The Stockfish developers (see AUTHORS file)
+  Copyright (C) 2004-2025 The Stockfish developers (see AUTHORS file)
 
   Stockfish is free software: you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
@@ -18,7 +18,9 @@
 
 #include "misc.h"
 
+#include <array>
 #include <atomic>
+#include <cassert>
 #include <cctype>
 #include <cmath>
 #include <cstdlib>
@@ -38,7 +40,7 @@ namespace Stockfish {
 namespace {
 
 // Version number or dev.
-constexpr std::string_view version = "17";
+constexpr std::string_view version = "17.1";
 
 // Our fancy logging facility. The trick here is to replace cin.rdbuf() and
 // cout.rdbuf() with two Tie objects that tie cin and cout to a file stream. We
@@ -122,7 +124,7 @@ class Logger {
 //
 // For releases (non-dev builds) we only include the version number:
 //      Stockfish version
-std::string engine_info(bool to_uci) {
+std::string engine_version_info() {
     std::stringstream ss;
     ss << "Stockfish " << version << std::setfill('0');
 
@@ -151,11 +153,14 @@ std::string engine_info(bool to_uci) {
 #endif
     }
 
-    ss << (to_uci ? "\nid author " : " by ") << "the Stockfish developers (see AUTHORS file)";
-
     return ss.str();
 }
 
+std::string engine_info(bool to_uci) {
+    return engine_version_info() + (to_uci ? "\nid author " : " by ")
+         + "the Stockfish developers (see AUTHORS file)";
+}
+
 
 // Returns a string trying to describe the compiler we use
 std::string compiler_info() {
@@ -282,9 +287,18 @@ namespace {
 
 template<size_t N>
 struct DebugInfo {
-    std::atomic<int64_t> data[N] = {0};
+    std::array<std::atomic<int64_t>, N> data = {0};
 
-    constexpr std::atomic<int64_t>& operator[](int index) { return data[index]; }
+    [[nodiscard]] constexpr std::atomic<int64_t>& operator[](size_t index) {
+        assert(index < N);
+        return data[index];
+    }
+
+    constexpr DebugInfo& operator=(const DebugInfo& other) {
+        for (size_t i = 0; i < N; i++)
+            data[i].store(other.data[i].load());
+        return *this;
+    }
 };
 
 struct DebugExtremes: public DebugInfo<3> {
@@ -294,54 +308,54 @@ struct DebugExtremes: public DebugInfo<3> {
     }
 };
 
-DebugInfo<2>  hit[MaxDebugSlots];
-DebugInfo<2>  mean[MaxDebugSlots];
-DebugInfo<3>  stdev[MaxDebugSlots];
-DebugInfo<6>  correl[MaxDebugSlots];
-DebugExtremes extremes[MaxDebugSlots];
+std::array<DebugInfo<2>, MaxDebugSlots>  hit;
+std::array<DebugInfo<2>, MaxDebugSlots>  mean;
+std::array<DebugInfo<3>, MaxDebugSlots>  stdev;
+std::array<DebugInfo<6>, MaxDebugSlots>  correl;
+std::array<DebugExtremes, MaxDebugSlots> extremes;
 
 }  // namespace
 
 void dbg_hit_on(bool cond, int slot) {
 
-    ++hit[slot][0];
+    ++hit.at(slot)[0];
     if (cond)
-        ++hit[slot][1];
+        ++hit.at(slot)[1];
 }
 
 void dbg_mean_of(int64_t value, int slot) {
 
-    ++mean[slot][0];
-    mean[slot][1] += value;
+    ++mean.at(slot)[0];
+    mean.at(slot)[1] += value;
 }
 
 void dbg_stdev_of(int64_t value, int slot) {
 
-    ++stdev[slot][0];
-    stdev[slot][1] += value;
-    stdev[slot][2] += value * value;
+    ++stdev.at(slot)[0];
+    stdev.at(slot)[1] += value;
+    stdev.at(slot)[2] += value * value;
 }
 
 void dbg_extremes_of(int64_t value, int slot) {
-    ++extremes[slot][0];
+    ++extremes.at(slot)[0];
 
-    int64_t current_max = extremes[slot][1].load();
-    while (current_max < value && !extremes[slot][1].compare_exchange_weak(current_max, value))
+    int64_t current_max = extremes.at(slot)[1].load();
+    while (current_max < value && !extremes.at(slot)[1].compare_exchange_weak(current_max, value))
     {}
 
-    int64_t current_min = extremes[slot][2].load();
-    while (current_min > value && !extremes[slot][2].compare_exchange_weak(current_min, value))
+    int64_t current_min = extremes.at(slot)[2].load();
+    while (current_min > value && !extremes.at(slot)[2].compare_exchange_weak(current_min, value))
     {}
 }
 
 void dbg_correl_of(int64_t value1, int64_t value2, int slot) {
 
-    ++correl[slot][0];
-    correl[slot][1] += value1;
-    correl[slot][2] += value1 * value1;
-    correl[slot][3] += value2;
-    correl[slot][4] += value2 * value2;
-    correl[slot][5] += value1 * value2;
+    ++correl.at(slot)[0];
+    correl.at(slot)[1] += value1;
+    correl.at(slot)[2] += value1 * value1;
+    correl.at(slot)[3] += value2;
+    correl.at(slot)[4] += value2 * value2;
+    correl.at(slot)[5] += value1 * value2;
 }
 
 void dbg_print() {
@@ -385,6 +399,13 @@ void dbg_print() {
         }
 }
 
+void dbg_clear() {
+    hit.fill({});
+    mean.fill({});
+    stdev.fill({});
+    correl.fill({});
+    extremes.fill({});
+}
 
 // Used to serialize access to std::cout
 // to avoid multiple threads writing at the same time.
@@ -451,7 +472,7 @@ void remove_whitespace(std::string& s) {
     s.erase(std::remove_if(s.begin(), s.end(), [](char c) { return std::isspace(c); }), s.end());
 }
 
-bool is_whitespace(const std::string& s) {
+bool is_whitespace(std::string_view s) {
     return std::all_of(s.begin(), s.end(), [](char c) { return std::isspace(c); });
 }
 

src/misc.h

@@ -1,6 +1,6 @@
 /*
   Stockfish, a UCI chess playing engine derived from Glaurung 2.1
-  Copyright (C) 2004-2024 The Stockfish developers (see AUTHORS file)
+  Copyright (C) 2004-2025 The Stockfish developers (see AUTHORS file)
 
   Stockfish is free software: you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
@@ -20,6 +20,7 @@
 #define MISC_H_INCLUDED
 
 #include <algorithm>
+#include <array>
 #include <cassert>
 #include <chrono>
 #include <cstddef>
@@ -28,6 +29,7 @@
 #include <iosfwd>
 #include <optional>
 #include <string>
+#include <string_view>
 #include <vector>
 
 #define stringify2(x) #x
@@ -35,6 +37,7 @@
 
 namespace Stockfish {
 
+std::string engine_version_info();
 std::string engine_info(bool to_uci = false);
 std::string compiler_info();
 
@@ -70,6 +73,7 @@ void dbg_stdev_of(int64_t value, int slot = 0);
 void dbg_extremes_of(int64_t value, int slot = 0);
 void dbg_correl_of(int64_t value1, int64_t value2, int slot = 0);
 void dbg_print();
+void dbg_clear();
 
 using TimePoint = std::chrono::milliseconds::rep;  // A value in milliseconds
 static_assert(sizeof(TimePoint) == sizeof(int64_t), "TimePoint should be 64 bits");
@@ -79,8 +83,8 @@ inline TimePoint now() {
       .count();
 }
 
-inline std::vector<std::string> split(const std::string& s, const std::string& delimiter) {
-    std::vector<std::string> res;
+inline std::vector<std::string_view> split(std::string_view s, std::string_view delimiter) {
+    std::vector<std::string_view> res;
 
     if (s.empty())
         return res;
@@ -102,7 +106,7 @@ inline std::vector<std::string> split(const std::string& s, const std::string& d
 }
 
 void remove_whitespace(std::string& s);
-bool is_whitespace(const std::string& s);
+bool is_whitespace(std::string_view s);
 
 enum SyncCout {
     IO_LOCK,
@@ -117,11 +121,8 @@ void sync_cout_start();
 void sync_cout_end();
 
 // True if and only if the binary is compiled on a little-endian machine
-static inline const union {
-    uint32_t i;
-    char     c[4];
-} Le                                    = {0x01020304};
-static inline const bool IsLittleEndian = (Le.c[0] == 4);
+static inline const std::uint16_t Le             = 1;
+static inline const bool          IsLittleEndian = *reinterpret_cast<const char*>(&Le) == 1;
 
 
 template<typename T, std::size_t MaxSize>
@@ -140,6 +141,97 @@ class ValueList {
 };
 
 
+template<typename T, std::size_t Size, std::size_t... Sizes>
+class MultiArray;
+
+namespace Detail {
+
+template<typename T, std::size_t Size, std::size_t... Sizes>
+struct MultiArrayHelper {
+    using ChildType = MultiArray<T, Sizes...>;
+};
+
+template<typename T, std::size_t Size>
+struct MultiArrayHelper<T, Size> {
+    using ChildType = T;
+};
+
+template<typename To, typename From>
+constexpr bool is_strictly_assignable_v =
+  std::is_assignable_v<To&, From> && (std::is_same_v<To, From> || !std::is_convertible_v<From, To>);
+
+}
+
+// MultiArray is a generic N-dimensional array.
+// The template parameters (Size and Sizes) encode the dimensions of the array.
+template<typename T, std::size_t Size, std::size_t... Sizes>
+class MultiArray {
+    using ChildType = typename Detail::MultiArrayHelper<T, Size, Sizes...>::ChildType;
+    using ArrayType = std::array<ChildType, Size>;
+    ArrayType data_;
+
+   public:
+    using value_type             = typename ArrayType::value_type;
+    using size_type              = typename ArrayType::size_type;
+    using difference_type        = typename ArrayType::difference_type;
+    using reference              = typename ArrayType::reference;
+    using const_reference        = typename ArrayType::const_reference;
+    using pointer                = typename ArrayType::pointer;
+    using const_pointer          = typename ArrayType::const_pointer;
+    using iterator               = typename ArrayType::iterator;
+    using const_iterator         = typename ArrayType::const_iterator;
+    using reverse_iterator       = typename ArrayType::reverse_iterator;
+    using const_reverse_iterator = typename ArrayType::const_reverse_iterator;
+
+    constexpr auto&       at(size_type index) noexcept { return data_.at(index); }
+    constexpr const auto& at(size_type index) const noexcept { return data_.at(index); }
+
+    constexpr auto&       operator[](size_type index) noexcept { return data_[index]; }
+    constexpr const auto& operator[](size_type index) const noexcept { return data_[index]; }
+
+    constexpr auto&       front() noexcept { return data_.front(); }
+    constexpr const auto& front() const noexcept { return data_.front(); }
+    constexpr auto&       back() noexcept { return data_.back(); }
+    constexpr const auto& back() const noexcept { return data_.back(); }
+
+    auto*       data() { return data_.data(); }
+    const auto* data() const { return data_.data(); }
+
+    constexpr auto begin() noexcept { return data_.begin(); }
+    constexpr auto end() noexcept { return data_.end(); }
+    constexpr auto begin() const noexcept { return data_.begin(); }
+    constexpr auto end() const noexcept { return data_.end(); }
+    constexpr auto cbegin() const noexcept { return data_.cbegin(); }
+    constexpr auto cend() const noexcept { return data_.cend(); }
+
+    constexpr auto rbegin() noexcept { return data_.rbegin(); }
+    constexpr auto rend() noexcept { return data_.rend(); }
+    constexpr auto rbegin() const noexcept { return data_.rbegin(); }
+    constexpr auto rend() const noexcept { return data_.rend(); }
+    constexpr auto crbegin() const noexcept { return data_.crbegin(); }
+    constexpr auto crend() const noexcept { return data_.crend(); }
+
+    constexpr bool      empty() const noexcept { return data_.empty(); }
+    constexpr size_type size() const noexcept { return data_.size(); }
+    constexpr size_type max_size() const noexcept { return data_.max_size(); }
+
+    template<typename U>
+    void fill(const U& v) {
+        static_assert(Detail::is_strictly_assignable_v<T, U>,
+                      "Cannot assign fill value to entry type");
+        for (auto& ele : data_)
+        {
+            if constexpr (sizeof...(Sizes) == 0)
+                ele = v;
+            else
+                ele.fill(v);
+        }
+    }
+
+    constexpr void swap(MultiArray<T, Size, Sizes...>& other) noexcept { data_.swap(other.data_); }
+};
+
+
 // xorshift64star Pseudo-Random Number Generator
 // This class is based on original code written and dedicated
 // to the public domain by Sebastiano Vigna (2014).

src/movegen.cpp

@@ -1,6 +1,6 @@
 /*
   Stockfish, a UCI chess playing engine derived from Glaurung 2.1
-  Copyright (C) 2004-2024 The Stockfish developers (see AUTHORS file)
+  Copyright (C) 2004-2025 The Stockfish developers (see AUTHORS file)
 
   Stockfish is free software: you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by

src/movegen.h

@@ -1,6 +1,6 @@
 /*
   Stockfish, a UCI chess playing engine derived from Glaurung 2.1
-  Copyright (C) 2004-2024 The Stockfish developers (see AUTHORS file)
+  Copyright (C) 2004-2025 The Stockfish developers (see AUTHORS file)
 
   Stockfish is free software: you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by

src/movepick.cpp

@@ -1,6 +1,6 @@
 /*
   Stockfish, a UCI chess playing engine derived from Glaurung 2.1
-  Copyright (C) 2004-2024 The Stockfish developers (see AUTHORS file)
+  Copyright (C) 2004-2025 The Stockfish developers (see AUTHORS file)
 
   Stockfish is free software: you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
@@ -18,11 +18,11 @@
 
 #include "movepick.h"
 
-#include <algorithm>
 #include <cassert>
-#include <utility>
+#include <limits>
 
 #include "bitboard.h"
+#include "misc.h"
 #include "position.h"
 
 namespace Stockfish {
@@ -82,16 +82,20 @@ MovePicker::MovePicker(const Position&              p,
                        Move                         ttm,
                        Depth                        d,
                        const ButterflyHistory*      mh,
+                       const LowPlyHistory*         lph,
                        const CapturePieceToHistory* cph,
                        const PieceToHistory**       ch,
-                       const PawnHistory*           ph) :
+                       const PawnHistory*           ph,
+                       int                          pl) :
     pos(p),
     mainHistory(mh),
+    lowPlyHistory(lph),
     captureHistory(cph),
     continuationHistory(ch),
     pawnHistory(ph),
     ttMove(ttm),
-    depth(d) {
+    depth(d),
+    ply(pl) {
 
     if (pos.checkers())
         stage = EVASION_TT + !(ttm && pos.pseudo_legal(ttm));
@@ -152,12 +156,13 @@ void MovePicker::score() {
             Square    to   = m.to_sq();
 
             // histories
-            m.value = (*mainHistory)[pos.side_to_move()][m.from_to()];
+            m.value = 2 * (*mainHistory)[pos.side_to_move()][m.from_to()];
             m.value += 2 * (*pawnHistory)[pawn_structure_index(pos)][pc][to];
-            m.value += 2 * (*continuationHistory[0])[pc][to];
+            m.value += (*continuationHistory[0])[pc][to];
             m.value += (*continuationHistory[1])[pc][to];
-            m.value += (*continuationHistory[2])[pc][to] / 3;
+            m.value += (*continuationHistory[2])[pc][to];
             m.value += (*continuationHistory[3])[pc][to];
+            m.value += (*continuationHistory[4])[pc][to] / 3;
             m.value += (*continuationHistory[5])[pc][to];
 
             // bonus for checks
@@ -171,16 +176,18 @@ void MovePicker::score() {
                                                : 0;
 
             // malus for putting piece en prise
-            m.value -= (pt == QUEEN  ? bool(to & threatenedByRook) * 49000
-                        : pt == ROOK ? bool(to & threatenedByMinor) * 24335
-                                     : bool(to & threatenedByPawn) * 14900);
+            m.value -= (pt == QUEEN ? bool(to & threatenedByRook) * 49000
+                        : pt == ROOK && bool(to & threatenedByMinor) ? 24335
+                                                                     : 0);
+
+            if (ply < LOW_PLY_HISTORY_SIZE)
+                m.value += 8 * (*lowPlyHistory)[ply][m.from_to()] / (1 + 2 * ply);
         }
 
         else  // Type == EVASIONS
         {
             if (pos.capture_stage(m))
-                m.value =
-                  PieceValue[pos.piece_on(m.to_sq())] - type_of(pos.moved_piece(m)) + (1 << 28);
+                m.value = PieceValue[pos.piece_on(m.to_sq())] + (1 << 28);
             else
                 m.value = (*mainHistory)[pos.side_to_move()][m.from_to()]
                         + (*continuationHistory[0])[pos.moved_piece(m)][m.to_sq()]
@@ -190,26 +197,20 @@ void MovePicker::score() {
 
 // Returns the next move satisfying a predicate function.
 // This never returns the TT move, as it was emitted before.
-template<MovePicker::PickType T, typename Pred>
+template<typename Pred>
 Move MovePicker::select(Pred filter) {
 
-    while (cur < endMoves)
-    {
-        if constexpr (T == Best)
-            std::swap(*cur, *std::max_element(cur, endMoves));
-
+    for (; cur < endMoves; ++cur)
         if (*cur != ttMove && filter())
             return *cur++;
 
-        cur++;
-    }
     return Move::none();
 }
 
 // This is the most important method of the MovePicker class. We emit one
 // new pseudo-legal move on every call until there are no more moves left,
 // picking the move with the highest score from a list of generated moves.
-Move MovePicker::next_move(bool skipQuiets) {
+Move MovePicker::next_move() {
 
     auto quiet_threshold = [](Depth d) { return -3560 * d; };
 
@@ -236,7 +237,7 @@ top:
         goto top;
 
     case GOOD_CAPTURE :
-        if (select<Next>([&]() {
+        if (select([&]() {
                 // Move losing capture to endBadCaptures to be tried later
                 return pos.see_ge(*cur, -cur->value / 18) ? true
                                                           : (*endBadCaptures++ = *cur, false);
@@ -260,7 +261,7 @@ top:
         [[fallthrough]];
 
     case GOOD_QUIET :
-        if (!skipQuiets && select<Next>([]() { return true; }))
+        if (!skipQuiets && select([]() { return true; }))
         {
             if ((cur - 1)->value > -7998 || (cur - 1)->value <= quiet_threshold(depth))
                 return *(cur - 1);
@@ -277,7 +278,7 @@ top:
         [[fallthrough]];
 
     case BAD_CAPTURE :
-        if (select<Next>([]() { return true; }))
+        if (select([]() { return true; }))
             return *(cur - 1);
 
         // Prepare the pointers to loop over the bad quiets
@@ -289,7 +290,7 @@ top:
 
     case BAD_QUIET :
         if (!skipQuiets)
-            return select<Next>([]() { return true; });
+            return select([]() { return true; });
 
         return Move::none();
 
@@ -298,21 +299,22 @@ top:
         endMoves = generate<EVASIONS>(pos, cur);
 
         score<EVASIONS>();
+        partial_insertion_sort(cur, endMoves, std::numeric_limits<int>::min());
         ++stage;
         [[fallthrough]];
 
     case EVASION :
-        return select<Best>([]() { return true; });
+    case QCAPTURE :
+        return select([]() { return true; });
 
     case PROBCUT :
-        return select<Next>([&]() { return pos.see_ge(*cur, threshold); });
-
-    case QCAPTURE :
-        return select<Next>([]() { return true; });
+        return select([&]() { return pos.see_ge(*cur, threshold); });
     }
 
     assert(false);
     return Move::none();  // Silence warning
 }
 
+void MovePicker::skip_quiet_moves() { skipQuiets = true; }
+
 }  // namespace Stockfish

src/movepick.h

@@ -1,6 +1,6 @@
 /*
   Stockfish, a UCI chess playing engine derived from Glaurung 2.1
-  Copyright (C) 2004-2024 The Stockfish developers (see AUTHORS file)
+  Copyright (C) 2004-2025 The Stockfish developers (see AUTHORS file)
 
   Stockfish is free software: you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
@@ -19,123 +19,13 @@
 #ifndef MOVEPICK_H_INCLUDED
 #define MOVEPICK_H_INCLUDED
 
-#include <algorithm>
-#include <array>
-#include <cassert>
-#include <cmath>
-#include <cstdint>
-#include <cstdlib>
-#include <limits>
-#include <type_traits>  // IWYU pragma: keep
-
+#include "history.h"
 #include "movegen.h"
-#include "position.h"
 #include "types.h"
 
 namespace Stockfish {
 
-constexpr int PAWN_HISTORY_SIZE        = 512;    // has to be a power of 2
-constexpr int CORRECTION_HISTORY_SIZE  = 16384;  // has to be a power of 2
-constexpr int CORRECTION_HISTORY_LIMIT = 1024;
-
-static_assert((PAWN_HISTORY_SIZE & (PAWN_HISTORY_SIZE - 1)) == 0,
-              "PAWN_HISTORY_SIZE has to be a power of 2");
-
-static_assert((CORRECTION_HISTORY_SIZE & (CORRECTION_HISTORY_SIZE - 1)) == 0,
-              "CORRECTION_HISTORY_SIZE has to be a power of 2");
-
-enum PawnHistoryType {
-    Normal,
-    Correction
-};
-
-template<PawnHistoryType T = Normal>
-inline int pawn_structure_index(const Position& pos) {
-    return pos.pawn_key() & ((T == Normal ? PAWN_HISTORY_SIZE : CORRECTION_HISTORY_SIZE) - 1);
-}
-
-// StatsEntry stores the stat table value. It is usually a number but could
-// be a move or even a nested history. We use a class instead of a naked value
-// to directly call history update operator<<() on the entry so to use stats
-// tables at caller sites as simple multi-dim arrays.
-template<typename T, int D>
-class StatsEntry {
-
-    T entry;
-
-   public:
-    void operator=(const T& v) { entry = v; }
-    T*   operator&() { return &entry; }
-    T*   operator->() { return &entry; }
-    operator const T&() const { return entry; }
-
-    void operator<<(int bonus) {
-        static_assert(D <= std::numeric_limits<T>::max(), "D overflows T");
-
-        // Make sure that bonus is in range [-D, D]
-        int clampedBonus = std::clamp(bonus, -D, D);
-        entry += clampedBonus - entry * std::abs(clampedBonus) / D;
-
-        assert(std::abs(entry) <= D);
-    }
-};
-
-// Stats is a generic N-dimensional array used to store various statistics.
-// The first template parameter T is the base type of the array, and the second
-// template parameter D limits the range of updates in [-D, D] when we update
-// values with the << operator, while the last parameters (Size and Sizes)
-// encode the dimensions of the array.
-template<typename T, int D, int Size, int... Sizes>
-struct Stats: public std::array<Stats<T, D, Sizes...>, Size> {
-    using stats = Stats<T, D, Size, Sizes...>;
-
-    void fill(const T& v) {
-
-        // For standard-layout 'this' points to the first struct member
-        assert(std::is_standard_layout_v<stats>);
-
-        using entry = StatsEntry<T, D>;
-        entry* p    = reinterpret_cast<entry*>(this);
-        std::fill(p, p + sizeof(*this) / sizeof(entry), v);
-    }
-};
-
-template<typename T, int D, int Size>
-struct Stats<T, D, Size>: public std::array<StatsEntry<T, D>, Size> {};
-
-// In stats table, D=0 means that the template parameter is not used
-enum StatsParams {
-    NOT_USED = 0
-};
-enum StatsType {
-    NoCaptures,
-    Captures
-};
-
-// ButterflyHistory records how often quiet moves have been successful or unsuccessful
-// during the current search, and is used for reduction and move ordering decisions.
-// It uses 2 tables (one for each color) indexed by the move's from and to squares,
-// see www.chessprogramming.org/Butterfly_Boards (~11 elo)
-using ButterflyHistory = Stats<int16_t, 7183, COLOR_NB, int(SQUARE_NB) * int(SQUARE_NB)>;
-
-// CapturePieceToHistory is addressed by a move's [piece][to][captured piece type]
-using CapturePieceToHistory = Stats<int16_t, 10692, PIECE_NB, SQUARE_NB, PIECE_TYPE_NB>;
-
-// PieceToHistory is like ButterflyHistory but is addressed by a move's [piece][to]
-using PieceToHistory = Stats<int16_t, 29952, PIECE_NB, SQUARE_NB>;
-
-// ContinuationHistory is the combined history of a given pair of moves, usually
-// the current one given a previous one. The nested history table is based on
-// PieceToHistory instead of ButterflyBoards.
-// (~63 elo)
-using ContinuationHistory = Stats<PieceToHistory, NOT_USED, PIECE_NB, SQUARE_NB>;
-
-// PawnHistory is addressed by the pawn structure and a move's [piece][to]
-using PawnHistory = Stats<int16_t, 8192, PAWN_HISTORY_SIZE, PIECE_NB, SQUARE_NB>;
-
-// CorrectionHistory is addressed by color and pawn structure
-using CorrectionHistory =
-  Stats<int16_t, CORRECTION_HISTORY_LIMIT, COLOR_NB, CORRECTION_HISTORY_SIZE>;
+class Position;
 
 // The MovePicker class is used to pick one pseudo-legal move at a time from the
 // current position. The most important method is next_move(), which emits one
@@ -145,11 +35,6 @@ using CorrectionHistory =
 // a cut-off first.
 class MovePicker {
 
-    enum PickType {
-        Next,
-        Best
-    };
-
    public:
     MovePicker(const MovePicker&)            = delete;
     MovePicker& operator=(const MovePicker&) = delete;
@@ -157,14 +42,17 @@ class MovePicker {
                Move,
                Depth,
                const ButterflyHistory*,
+               const LowPlyHistory*,
                const CapturePieceToHistory*,
                const PieceToHistory**,
-               const PawnHistory*);
+               const PawnHistory*,
+               int);
     MovePicker(const Position&, Move, int, const CapturePieceToHistory*);
-    Move next_move(bool skipQuiets = false);
+    Move next_move();
+    void skip_quiet_moves();
 
    private:
-    template<PickType T, typename Pred>
+    template<typename Pred>
     Move select(Pred);
     template<GenType>
     void     score();
@@ -173,6 +61,7 @@ class MovePicker {
 
     const Position&              pos;
     const ButterflyHistory*      mainHistory;
+    const LowPlyHistory*         lowPlyHistory;
     const CapturePieceToHistory* captureHistory;
     const PieceToHistory**       continuationHistory;
     const PawnHistory*           pawnHistory;
@@ -181,6 +70,8 @@ class MovePicker {
     int                          stage;
     int                          threshold;
     Depth                        depth;
+    int                          ply;
+    bool                         skipQuiets = false;
     ExtMove                      moves[MAX_MOVES];
 };
 

src/nnue/features/half_ka_v2_hm.cpp

@@ -1,6 +1,6 @@
 /*
   Stockfish, a UCI chess playing engine derived from Glaurung 2.1
-  Copyright (C) 2004-2024 The Stockfish developers (see AUTHORS file)
+  Copyright (C) 2004-2025 The Stockfish developers (see AUTHORS file)
 
   Stockfish is free software: you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
@@ -77,12 +77,8 @@ template void HalfKAv2_hm::append_changed_indices<BLACK>(Square            ksq,
                                                          IndexList&        removed,
                                                          IndexList&        added);
 
-int HalfKAv2_hm::update_cost(const StateInfo* st) { return st->dirtyPiece.dirty_num; }
-
-int HalfKAv2_hm::refresh_cost(const Position& pos) { return pos.count<ALL_PIECES>(); }
-
-bool HalfKAv2_hm::requires_refresh(const StateInfo* st, Color perspective) {
-    return st->dirtyPiece.piece[0] == make_piece(perspective, KING);
+bool HalfKAv2_hm::requires_refresh(const DirtyPiece& dirtyPiece, Color perspective) {
+    return dirtyPiece.piece[0] == make_piece(perspective, KING);
 }
 
 }  // namespace Stockfish::Eval::NNUE::Features

src/nnue/features/half_ka_v2_hm.h

@@ -1,6 +1,6 @@
 /*
   Stockfish, a UCI chess playing engine derived from Glaurung 2.1
-  Copyright (C) 2004-2024 The Stockfish developers (see AUTHORS file)
+  Copyright (C) 2004-2025 The Stockfish developers (see AUTHORS file)
 
   Stockfish is free software: you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
@@ -28,7 +28,6 @@
 #include "../nnue_common.h"
 
 namespace Stockfish {
-struct StateInfo;
 class Position;
 }
 
@@ -135,14 +134,9 @@ class HalfKAv2_hm {
     static void
     append_changed_indices(Square ksq, const DirtyPiece& dp, IndexList& removed, IndexList& added);
 
-    // Returns the cost of updating one perspective, the most costly one.
-    // Assumes no refresh needed.
-    static int update_cost(const StateInfo* st);
-    static int refresh_cost(const Position& pos);
-
-    // Returns whether the change stored in this StateInfo means
+    // Returns whether the change stored in this DirtyPiece means
     // that a full accumulator refresh is required.
-    static bool requires_refresh(const StateInfo* st, Color perspective);
+    static bool requires_refresh(const DirtyPiece& dirtyPiece, Color perspective);
 };
 
 }  // namespace Stockfish::Eval::NNUE::Features

src/nnue/layers/affine_transform.h

@@ -1,6 +1,6 @@
 /*
   Stockfish, a UCI chess playing engine derived from Glaurung 2.1
-  Copyright (C) 2004-2024 The Stockfish developers (see AUTHORS file)
+  Copyright (C) 2004-2025 The Stockfish developers (see AUTHORS file)
 
   Stockfish is free software: you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
@@ -102,7 +102,7 @@ static void affine_transform_non_ssse3(std::int32_t*       output,
             product           = vmlal_s8(product, inputVector[j * 2 + 1], row[j * 2 + 1]);
             sum               = vpadalq_s16(sum, product);
         }
-        output[i] = sum[0] + sum[1] + sum[2] + sum[3];
+        output[i] = Simd::neon_m128_reduce_add_epi32(sum);
 
         #endif
     }

src/nnue/layers/affine_transform_sparse_input.h

@@ -1,6 +1,6 @@
 /*
   Stockfish, a UCI chess playing engine derived from Glaurung 2.1
-  Copyright (C) 2004-2024 The Stockfish developers (see AUTHORS file)
+  Copyright (C) 2004-2025 The Stockfish developers (see AUTHORS file)
 
   Stockfish is free software: you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
@@ -38,17 +38,41 @@
 namespace Stockfish::Eval::NNUE::Layers {
 
 #if (USE_SSSE3 | (USE_NEON >= 8))
-alignas(CacheLineSize) static inline const
-  std::array<std::array<std::uint16_t, 8>, 256> lookup_indices = []() {
-      std::array<std::array<std::uint16_t, 8>, 256> v{};
-      for (unsigned i = 0; i < 256; ++i)
-      {
-          std::uint64_t j = i, k = 0;
-          while (j)
-              v[i][k++] = pop_lsb(j);
-      }
-      return v;
-  }();
+static constexpr int lsb_index64[64] = {
+  0,  47, 1,  56, 48, 27, 2,  60, 57, 49, 41, 37, 28, 16, 3,  61, 54, 58, 35, 52, 50, 42,
+  21, 44, 38, 32, 29, 23, 17, 11, 4,  62, 46, 55, 26, 59, 40, 36, 15, 53, 34, 51, 20, 43,
+  31, 22, 10, 45, 25, 39, 14, 33, 19, 30, 9,  24, 13, 18, 8,  12, 7,  6,  5,  63};
+
+constexpr int constexpr_lsb(uint64_t bb) {
+    assert(bb != 0);
+    constexpr uint64_t debruijn64 = 0x03F79D71B4CB0A89ULL;
+    return lsb_index64[((bb ^ (bb - 1)) * debruijn64) >> 58];
+}
+
+alignas(CacheLineSize) static constexpr struct OffsetIndices {
+
+    #if (USE_SSE41)
+    std::uint8_t offset_indices[256][8];
+    #else
+    std::uint16_t offset_indices[256][8];
+    #endif
+
+    constexpr OffsetIndices() :
+        offset_indices() {
+        for (int i = 0; i < 256; ++i)
+        {
+            std::uint64_t j = i, k = 0;
+            while (j)
+            {
+                offset_indices[i][k++] = constexpr_lsb(j);
+                j &= j - 1;
+            }
+            while (k < 8)
+                offset_indices[i][k++] = 0;
+        }
+    }
+
+} Lookup;
 
 // Find indices of nonzero numbers in an int32_t array
 template<const IndexType InputDimensions>
@@ -74,7 +98,11 @@ void find_nnz(const std::int32_t* input, std::uint16_t* out, IndexType& count_ou
     using vec128_t = __m128i;
         #define vec128_zero _mm_setzero_si128()
         #define vec128_set_16(a) _mm_set1_epi16(a)
-        #define vec128_load(a) _mm_load_si128(a)
+        #if (USE_SSE41)
+            #define vec128_load(a) _mm_cvtepu8_epi16(_mm_loadl_epi64(a))
+        #else
+            #define vec128_load(a) _mm_load_si128(a)
+        #endif
         #define vec128_storeu(a, b) _mm_storeu_si128(a, b)
         #define vec128_add(a, b) _mm_add_epi16(a, b)
     #elif defined(USE_NEON)
@@ -110,9 +138,9 @@ void find_nnz(const std::int32_t* input, std::uint16_t* out, IndexType& count_ou
         }
         for (IndexType j = 0; j < OutputsPerChunk; ++j)
         {
-            const auto lookup = (nnz >> (j * 8)) & 0xFF;
-            const auto offsets =
-              vec128_load(reinterpret_cast<const vec128_t*>(&lookup_indices[lookup]));
+            const unsigned lookup = (nnz >> (j * 8)) & 0xFF;
+            const vec128_t offsets =
+              vec128_load(reinterpret_cast<const vec128_t*>(&Lookup.offset_indices[lookup]));
             vec128_storeu(reinterpret_cast<vec128_t*>(out + count), vec128_add(base, offsets));
             count += popcount(lookup);
             base = vec128_add(base, increment);

src/nnue/layers/clipped_relu.h

@@ -1,6 +1,6 @@
 /*
   Stockfish, a UCI chess playing engine derived from Glaurung 2.1
-  Copyright (C) 2004-2024 The Stockfish developers (see AUTHORS file)
+  Copyright (C) 2004-2025 The Stockfish developers (see AUTHORS file)
 
   Stockfish is free software: you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by

src/nnue/layers/simd.h

@@ -1,6 +1,6 @@
 /*
   Stockfish, a UCI chess playing engine derived from Glaurung 2.1
-  Copyright (C) 2004-2024 The Stockfish developers (see AUTHORS file)
+  Copyright (C) 2004-2025 The Stockfish developers (see AUTHORS file)
 
   Stockfish is free software: you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by

src/nnue/layers/sqr_clipped_relu.h

@@ -1,6 +1,6 @@
 /*
   Stockfish, a UCI chess playing engine derived from Glaurung 2.1
-  Copyright (C) 2004-2024 The Stockfish developers (see AUTHORS file)
+  Copyright (C) 2004-2025 The Stockfish developers (see AUTHORS file)
 
   Stockfish is free software: you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by

src/nnue/network.cpp

@@ -1,6 +1,6 @@
 /*
   Stockfish, a UCI chess playing engine derived from Glaurung 2.1
-  Copyright (C) 2004-2024 The Stockfish developers (see AUTHORS file)
+  Copyright (C) 2004-2025 The Stockfish developers (see AUTHORS file)
 
   Stockfish is free software: you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
@@ -26,8 +26,10 @@
 #include <type_traits>
 #include <vector>
 
-#include "../evaluate.h"
+#define INCBIN_SILENCE_BITCODE_WARNING
 #include "../incbin/incbin.h"
+
+#include "../evaluate.h"
 #include "../memory.h"
 #include "../misc.h"
 #include "../position.h"
@@ -36,7 +38,6 @@
 #include "nnue_common.h"
 #include "nnue_misc.h"
 
-namespace {
 // Macro to embed the default efficiently updatable neural network (NNUE) file
 // data in the engine binary (using incbin.h, by Dale Weiler).
 // This macro invocation will declare the following three variables
@@ -56,6 +57,8 @@ const unsigned char* const gEmbeddedNNUESmallEnd     = &gEmbeddedNNUESmallData[1
 const unsigned int         gEmbeddedNNUESmallSize    = 1;
 #endif
 
+namespace {
+
 struct EmbeddedNNUE {
     EmbeddedNNUE(const unsigned char* embeddedData,
                  const unsigned char* embeddedEnd,
@@ -98,7 +101,7 @@ bool read_parameters(std::istream& stream, T& reference) {
 
 // Write evaluation function parameters
 template<typename T>
-bool write_parameters(std::ostream& stream, const T& reference) {
+bool write_parameters(std::ostream& stream, T& reference) {
 
     write_little_endian<std::uint32_t>(stream, T::get_hash_value());
     return reference.write_parameters(stream);
@@ -207,6 +210,7 @@ bool Network<Arch, Transformer>::save(const std::optional<std::string>& filename
 template<typename Arch, typename Transformer>
 NetworkOutput
 Network<Arch, Transformer>::evaluate(const Position&                         pos,
+                                     AccumulatorStack&                       accumulatorStack,
                                      AccumulatorCaches::Cache<FTDimensions>* cache) const {
     // We manually align the arrays on the stack because with gcc < 9.3
     // overaligning stack variables with alignas() doesn't work correctly.
@@ -226,55 +230,59 @@ Network<Arch, Transformer>::evaluate(const Position&                         pos
 
     ASSERT_ALIGNED(transformedFeatures, alignment);
 
-    const int  bucket     = (pos.count<ALL_PIECES>() - 1) / 4;
-    const auto psqt       = featureTransformer->transform(pos, cache, transformedFeatures, bucket);
+    const int  bucket = (pos.count<ALL_PIECES>() - 1) / 4;
+    const auto psqt =
+      featureTransformer->transform(pos, accumulatorStack, cache, transformedFeatures, bucket);
     const auto positional = network[bucket].propagate(transformedFeatures);
     return {static_cast<Value>(psqt / OutputScale), static_cast<Value>(positional / OutputScale)};
 }
 
 
 template<typename Arch, typename Transformer>
-void Network<Arch, Transformer>::verify(std::string evalfilePath) const {
+void Network<Arch, Transformer>::verify(std::string                                  evalfilePath,
+                                        const std::function<void(std::string_view)>& f) const {
     if (evalfilePath.empty())
         evalfilePath = evalFile.defaultName;
 
     if (evalFile.current != evalfilePath)
     {
-        std::string msg1 =
-          "Network evaluation parameters compatible with the engine must be available.";
-        std::string msg2 = "The network file " + evalfilePath + " was not loaded successfully.";
-        std::string msg3 = "The UCI option EvalFile might need to specify the full path, "
-                           "including the directory name, to the network file.";
-        std::string msg4 = "The default net can be downloaded from: "
-                           "https://tests.stockfishchess.org/api/nn/"
-                         + evalFile.defaultName;
-        std::string msg5 = "The engine will be terminated now.";
+        if (f)
+        {
+            std::string msg1 =
+              "Network evaluation parameters compatible with the engine must be available.";
+            std::string msg2 = "The network file " + evalfilePath + " was not loaded successfully.";
+            std::string msg3 = "The UCI option EvalFile might need to specify the full path, "
+                               "including the directory name, to the network file.";
+            std::string msg4 = "The default net can be downloaded from: "
+                               "https://tests.stockfishchess.org/api/nn/"
+                             + evalFile.defaultName;
+            std::string msg5 = "The engine will be terminated now.";
+
+            std::string msg = "ERROR: " + msg1 + '\n' + "ERROR: " + msg2 + '\n' + "ERROR: " + msg3
+                            + '\n' + "ERROR: " + msg4 + '\n' + "ERROR: " + msg5 + '\n';
+
+            f(msg);
+        }
 
-        sync_cout << "info string ERROR: " << msg1 << sync_endl;
-        sync_cout << "info string ERROR: " << msg2 << sync_endl;
-        sync_cout << "info string ERROR: " << msg3 << sync_endl;
-        sync_cout << "info string ERROR: " << msg4 << sync_endl;
-        sync_cout << "info string ERROR: " << msg5 << sync_endl;
         exit(EXIT_FAILURE);
     }
 
-    size_t size = sizeof(*featureTransformer) + sizeof(Arch) * LayerStacks;
-    sync_cout << "info string NNUE evaluation using " << evalfilePath << " ("
-              << size / (1024 * 1024) << "MiB, (" << featureTransformer->InputDimensions << ", "
-              << network[0].TransformedFeatureDimensions << ", " << network[0].FC_0_OUTPUTS << ", "
-              << network[0].FC_1_OUTPUTS << ", 1))" << sync_endl;
+    if (f)
+    {
+        size_t size = sizeof(*featureTransformer) + sizeof(Arch) * LayerStacks;
+        f("NNUE evaluation using " + evalfilePath + " (" + std::to_string(size / (1024 * 1024))
+          + "MiB, (" + std::to_string(featureTransformer->InputDimensions) + ", "
+          + std::to_string(network[0].TransformedFeatureDimensions) + ", "
+          + std::to_string(network[0].FC_0_OUTPUTS) + ", " + std::to_string(network[0].FC_1_OUTPUTS)
+          + ", 1))");
+    }
 }
 
 
-template<typename Arch, typename Transformer>
-void Network<Arch, Transformer>::hint_common_access(
-  const Position& pos, AccumulatorCaches::Cache<FTDimensions>* cache) const {
-    featureTransformer->hint_common_access(pos, cache);
-}
-
 template<typename Arch, typename Transformer>
 NnueEvalTrace
 Network<Arch, Transformer>::trace_evaluate(const Position&                         pos,
+                                           AccumulatorStack&                       accumulatorStack,
                                            AccumulatorCaches::Cache<FTDimensions>* cache) const {
     // We manually align the arrays on the stack because with gcc < 9.3
     // overaligning stack variables with alignas() doesn't work correctly.
@@ -298,7 +306,7 @@ Network<Arch, Transformer>::trace_evaluate(const Position&
     for (IndexType bucket = 0; bucket < LayerStacks; ++bucket)
     {
         const auto materialist =
-          featureTransformer->transform(pos, cache, transformedFeatures, bucket);
+          featureTransformer->transform(pos, accumulatorStack, cache, transformedFeatures, bucket);
         const auto positional = network[bucket].propagate(transformedFeatures);
 
         t.psqt[bucket]       = static_cast<Value>(materialist / OutputScale);
@@ -442,14 +450,14 @@ bool Network<Arch, Transformer>::write_parameters(std::ostream&      stream,
     return bool(stream);
 }
 
-// Explicit template instantiation
+// Explicit template instantiations
 
 template class Network<
   NetworkArchitecture<TransformedFeatureDimensionsBig, L2Big, L3Big>,
-  FeatureTransformer<TransformedFeatureDimensionsBig, &StateInfo::accumulatorBig>>;
+  FeatureTransformer<TransformedFeatureDimensionsBig, &AccumulatorState::accumulatorBig>>;
 
 template class Network<
   NetworkArchitecture<TransformedFeatureDimensionsSmall, L2Small, L3Small>,
-  FeatureTransformer<TransformedFeatureDimensionsSmall, &StateInfo::accumulatorSmall>>;
+  FeatureTransformer<TransformedFeatureDimensionsSmall, &AccumulatorState::accumulatorSmall>>;
 
 }  // namespace Stockfish::Eval::NNUE

src/nnue/network.h

@@ -1,6 +1,6 @@
 /*
   Stockfish, a UCI chess playing engine derived from Glaurung 2.1
-  Copyright (C) 2004-2024 The Stockfish developers (see AUTHORS file)
+  Copyright (C) 2004-2025 The Stockfish developers (see AUTHORS file)
 
   Stockfish is free software: you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
@@ -20,20 +20,25 @@
 #define NETWORK_H_INCLUDED
 
 #include <cstdint>
+#include <functional>
 #include <iostream>
 #include <optional>
 #include <string>
+#include <string_view>
 #include <tuple>
 #include <utility>
 
 #include "../memory.h"
-#include "../position.h"
 #include "../types.h"
 #include "nnue_accumulator.h"
 #include "nnue_architecture.h"
 #include "nnue_feature_transformer.h"
 #include "nnue_misc.h"
 
+namespace Stockfish {
+class Position;
+}
+
 namespace Stockfish::Eval::NNUE {
 
 enum class EmbeddedNNUEType {
@@ -62,14 +67,13 @@ class Network {
     bool save(const std::optional<std::string>& filename) const;
 
     NetworkOutput evaluate(const Position&                         pos,
+                           AccumulatorStack&                       accumulatorStack,
                            AccumulatorCaches::Cache<FTDimensions>* cache) const;
 
 
-    void hint_common_access(const Position&                         pos,
-                            AccumulatorCaches::Cache<FTDimensions>* cache) const;
-
-    void          verify(std::string evalfilePath) const;
+    void verify(std::string evalfilePath, const std::function<void(std::string_view)>&) const;
     NnueEvalTrace trace_evaluate(const Position&                         pos,
+                                 AccumulatorStack&                       accumulatorStack,
                                  AccumulatorCaches::Cache<FTDimensions>* cache) const;
 
    private:
@@ -101,16 +105,18 @@ class Network {
 
     template<IndexType Size>
     friend struct AccumulatorCaches::Cache;
+
+    friend class AccumulatorStack;
 };
 
 // Definitions of the network types
 using SmallFeatureTransformer =
-  FeatureTransformer<TransformedFeatureDimensionsSmall, &StateInfo::accumulatorSmall>;
+  FeatureTransformer<TransformedFeatureDimensionsSmall, &AccumulatorState::accumulatorSmall>;
 using SmallNetworkArchitecture =
   NetworkArchitecture<TransformedFeatureDimensionsSmall, L2Small, L3Small>;
 
 using BigFeatureTransformer =
-  FeatureTransformer<TransformedFeatureDimensionsBig, &StateInfo::accumulatorBig>;
+  FeatureTransformer<TransformedFeatureDimensionsBig, &AccumulatorState::accumulatorBig>;
 using BigNetworkArchitecture = NetworkArchitecture<TransformedFeatureDimensionsBig, L2Big, L3Big>;
 
 using NetworkBig   = Network<BigNetworkArchitecture, BigFeatureTransformer>;

src/nnue/nnue_accumulator.cpp

@@ -0,0 +1,619 @@
+/*
+  Stockfish, a UCI chess playing engine derived from Glaurung 2.1
+  Copyright (C) 2004-2025 The Stockfish developers (see AUTHORS file)
+
+  Stockfish is free software: you can redistribute it and/or modify
+  it under the terms of the GNU General Public License as published by
+  the Free Software Foundation, either version 3 of the License, or
+  (at your option) any later version.
+
+  Stockfish is distributed in the hope that it will be useful,
+  but WITHOUT ANY WARRANTY; without even the implied warranty of
+  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+  GNU General Public License for more details.
+
+  You should have received a copy of the GNU General Public License
+  along with this program.  If not, see <http://www.gnu.org/licenses/>.
+*/
+
+#include "nnue_accumulator.h"
+
+#include <cassert>
+#include <initializer_list>
+#include <memory>
+
+#include "../bitboard.h"
+#include "../position.h"
+#include "../types.h"
+#include "network.h"
+#include "nnue_architecture.h"
+#include "nnue_common.h"
+#include "nnue_feature_transformer.h"
+
+namespace Stockfish::Eval::NNUE {
+
+#if defined(__GNUC__) && !defined(__clang__)
+    #define sf_assume(cond) \
+        do \
+        { \
+            if (!(cond)) \
+                __builtin_unreachable(); \
+        } while (0)
+#else
+    // do nothing for other compilers
+    #define sf_assume(cond)
+#endif
+
+namespace {
+
+template<Color                                     Perspective,
+         IncUpdateDirection                        Direction = FORWARD,
+         IndexType                                 TransformedFeatureDimensions,
+         Accumulator<TransformedFeatureDimensions> AccumulatorState::*accPtr>
+void update_accumulator_incremental(
+  const FeatureTransformer<TransformedFeatureDimensions, accPtr>& featureTransformer,
+  const Square                                                    ksq,
+  AccumulatorState&                                               target_state,
+  const AccumulatorState&                                         computed);
+
+template<Color Perspective, IndexType Dimensions, Accumulator<Dimensions> AccumulatorState::*accPtr>
+void update_accumulator_refresh_cache(
+  const FeatureTransformer<Dimensions, accPtr>& featureTransformer,
+  const Position&                               pos,
+  AccumulatorState&                             accumulatorState,
+  AccumulatorCaches::Cache<Dimensions>&         cache);
+
+}
+
+void AccumulatorState::reset(const DirtyPiece& dp) noexcept {
+    dirtyPiece = dp;
+    accumulatorBig.computed.fill(false);
+    accumulatorSmall.computed.fill(false);
+}
+
+const AccumulatorState& AccumulatorStack::latest() const noexcept {
+    return m_accumulators[m_current_idx - 1];
+}
+
+AccumulatorState& AccumulatorStack::mut_latest() noexcept {
+    return m_accumulators[m_current_idx - 1];
+}
+
+void AccumulatorStack::reset(const Position&    rootPos,
+                             const Networks&    networks,
+                             AccumulatorCaches& caches) noexcept {
+    m_current_idx = 1;
+
+    update_accumulator_refresh_cache<WHITE, TransformedFeatureDimensionsBig,
+                                     &AccumulatorState::accumulatorBig>(
+      *networks.big.featureTransformer, rootPos, m_accumulators[0], caches.big);
+    update_accumulator_refresh_cache<BLACK, TransformedFeatureDimensionsBig,
+                                     &AccumulatorState::accumulatorBig>(
+      *networks.big.featureTransformer, rootPos, m_accumulators[0], caches.big);
+
+    update_accumulator_refresh_cache<WHITE, TransformedFeatureDimensionsSmall,
+                                     &AccumulatorState::accumulatorSmall>(
+      *networks.small.featureTransformer, rootPos, m_accumulators[0], caches.small);
+    update_accumulator_refresh_cache<BLACK, TransformedFeatureDimensionsSmall,
+                                     &AccumulatorState::accumulatorSmall>(
+      *networks.small.featureTransformer, rootPos, m_accumulators[0], caches.small);
+}
+
+void AccumulatorStack::push(const DirtyPiece& dirtyPiece) noexcept {
+    assert(m_current_idx + 1 < m_accumulators.size());
+    m_accumulators[m_current_idx].reset(dirtyPiece);
+    m_current_idx++;
+}
+
+void AccumulatorStack::pop() noexcept {
+    assert(m_current_idx > 1);
+    m_current_idx--;
+}
+
+template<IndexType Dimensions, Accumulator<Dimensions> AccumulatorState::*accPtr>
+void AccumulatorStack::evaluate(const Position&                               pos,
+                                const FeatureTransformer<Dimensions, accPtr>& featureTransformer,
+                                AccumulatorCaches::Cache<Dimensions>&         cache) noexcept {
+
+    evaluate_side<WHITE>(pos, featureTransformer, cache);
+    evaluate_side<BLACK>(pos, featureTransformer, cache);
+}
+
+template<Color Perspective, IndexType Dimensions, Accumulator<Dimensions> AccumulatorState::*accPtr>
+void AccumulatorStack::evaluate_side(
+  const Position&                               pos,
+  const FeatureTransformer<Dimensions, accPtr>& featureTransformer,
+  AccumulatorCaches::Cache<Dimensions>&         cache) noexcept {
+
+    const auto last_usable_accum = find_last_usable_accumulator<Perspective, Dimensions, accPtr>();
+
+    if ((m_accumulators[last_usable_accum].*accPtr).computed[Perspective])
+        forward_update_incremental<Perspective>(pos, featureTransformer, last_usable_accum);
+
+    else
+    {
+        update_accumulator_refresh_cache<Perspective>(featureTransformer, pos, mut_latest(), cache);
+        backward_update_incremental<Perspective>(pos, featureTransformer, last_usable_accum);
+    }
+}
+
+// Find the earliest usable accumulator, this can either be a computed accumulator or the accumulator
+// state just before a change that requires full refresh.
+template<Color Perspective, IndexType Dimensions, Accumulator<Dimensions> AccumulatorState::*accPtr>
+std::size_t AccumulatorStack::find_last_usable_accumulator() const noexcept {
+
+    for (std::size_t curr_idx = m_current_idx - 1; curr_idx > 0; curr_idx--)
+    {
+        if ((m_accumulators[curr_idx].*accPtr).computed[Perspective])
+            return curr_idx;
+
+        if (FeatureSet::requires_refresh(m_accumulators[curr_idx].dirtyPiece, Perspective))
+            return curr_idx;
+    }
+
+    return 0;
+}
+
+template<Color Perspective, IndexType Dimensions, Accumulator<Dimensions> AccumulatorState::*accPtr>
+void AccumulatorStack::forward_update_incremental(
+  const Position&                               pos,
+  const FeatureTransformer<Dimensions, accPtr>& featureTransformer,
+  const std::size_t                             begin) noexcept {
+
+    assert(begin < m_accumulators.size());
+    assert((m_accumulators[begin].*accPtr).computed[Perspective]);
+
+    const Square ksq = pos.square<KING>(Perspective);
+
+    for (std::size_t next = begin + 1; next < m_current_idx; next++)
+        update_accumulator_incremental<Perspective>(featureTransformer, ksq, m_accumulators[next],
+                                                    m_accumulators[next - 1]);
+
+    assert((latest().*accPtr).computed[Perspective]);
+}
+
+template<Color Perspective, IndexType Dimensions, Accumulator<Dimensions> AccumulatorState::*accPtr>
+void AccumulatorStack::backward_update_incremental(
+  const Position&                               pos,
+  const FeatureTransformer<Dimensions, accPtr>& featureTransformer,
+  const std::size_t                             end) noexcept {
+
+    assert(end < m_accumulators.size());
+    assert(end < m_current_idx);
+    assert((latest().*accPtr).computed[Perspective]);
+
+    const Square ksq = pos.square<KING>(Perspective);
+
+    for (std::size_t next = m_current_idx - 2; next >= end; next--)
+        update_accumulator_incremental<Perspective, BACKWARDS>(
+          featureTransformer, ksq, m_accumulators[next], m_accumulators[next + 1]);
+
+    assert((m_accumulators[end].*accPtr).computed[Perspective]);
+}
+
+// Explicit template instantiations
+template void
+AccumulatorStack::evaluate<TransformedFeatureDimensionsBig, &AccumulatorState::accumulatorBig>(
+  const Position& pos,
+  const FeatureTransformer<TransformedFeatureDimensionsBig, &AccumulatorState::accumulatorBig>&
+                                                             featureTransformer,
+  AccumulatorCaches::Cache<TransformedFeatureDimensionsBig>& cache) noexcept;
+template void
+AccumulatorStack::evaluate<TransformedFeatureDimensionsSmall, &AccumulatorState::accumulatorSmall>(
+  const Position& pos,
+  const FeatureTransformer<TransformedFeatureDimensionsSmall, &AccumulatorState::accumulatorSmall>&
+                                                               featureTransformer,
+  AccumulatorCaches::Cache<TransformedFeatureDimensionsSmall>& cache) noexcept;
+
+
+namespace {
+
+template<Color                                     Perspective,
+         IncUpdateDirection                        Direction,
+         IndexType                                 TransformedFeatureDimensions,
+         Accumulator<TransformedFeatureDimensions> AccumulatorState::*accPtr>
+void update_accumulator_incremental(
+  const FeatureTransformer<TransformedFeatureDimensions, accPtr>& featureTransformer,
+  const Square                                                    ksq,
+  AccumulatorState&                                               target_state,
+  const AccumulatorState&                                         computed) {
+    [[maybe_unused]] constexpr bool Forward   = Direction == FORWARD;
+    [[maybe_unused]] constexpr bool Backwards = Direction == BACKWARDS;
+
+    assert(Forward != Backwards);
+
+    assert((computed.*accPtr).computed[Perspective]);
+    assert(!(target_state.*accPtr).computed[Perspective]);
+
+    // The size must be enough to contain the largest possible update.
+    // That might depend on the feature set and generally relies on the
+    // feature set's update cost calculation to be correct and never allow
+    // updates with more added/removed features than MaxActiveDimensions.
+    // In this case, the maximum size of both feature addition and removal
+    // is 2, since we are incrementally updating one move at a time.
+    FeatureSet::IndexList removed, added;
+    if constexpr (Forward)
+        FeatureSet::append_changed_indices<Perspective>(ksq, target_state.dirtyPiece, removed,
+                                                        added);
+    else
+        FeatureSet::append_changed_indices<Perspective>(ksq, computed.dirtyPiece, added, removed);
+
+    if (removed.size() == 0 && added.size() == 0)
+    {
+        std::memcpy((target_state.*accPtr).accumulation[Perspective],
+                    (computed.*accPtr).accumulation[Perspective],
+                    TransformedFeatureDimensions * sizeof(BiasType));
+        std::memcpy((target_state.*accPtr).psqtAccumulation[Perspective],
+                    (computed.*accPtr).psqtAccumulation[Perspective],
+                    PSQTBuckets * sizeof(PSQTWeightType));
+    }
+    else
+    {
+        assert(added.size() == 1 || added.size() == 2);
+        assert(removed.size() == 1 || removed.size() == 2);
+
+        if (Forward)
+            assert(added.size() <= removed.size());
+        else
+            assert(removed.size() <= added.size());
+
+        // Workaround compiler warning for uninitialized variables, replicated on
+        // profile builds on windows with gcc 14.2.0.
+        // TODO remove once unneeded
+        sf_assume(added.size() == 1 || added.size() == 2);
+        sf_assume(removed.size() == 1 || removed.size() == 2);
+
+#ifdef VECTOR
+        auto* accIn =
+          reinterpret_cast<const vec_t*>(&(computed.*accPtr).accumulation[Perspective][0]);
+        auto* accOut =
+          reinterpret_cast<vec_t*>(&(target_state.*accPtr).accumulation[Perspective][0]);
+
+        const IndexType offsetA0 = TransformedFeatureDimensions * added[0];
+        auto* columnA0 = reinterpret_cast<const vec_t*>(&featureTransformer.weights[offsetA0]);
+        const IndexType offsetR0 = TransformedFeatureDimensions * removed[0];
+        auto* columnR0 = reinterpret_cast<const vec_t*>(&featureTransformer.weights[offsetR0]);
+
+        if ((Forward && removed.size() == 1) || (Backwards && added.size() == 1))
+        {
+            assert(added.size() == 1 && removed.size() == 1);
+            for (IndexType i = 0;
+                 i < TransformedFeatureDimensions * sizeof(WeightType) / sizeof(vec_t); ++i)
+                accOut[i] = vec_add_16(vec_sub_16(accIn[i], columnR0[i]), columnA0[i]);
+        }
+        else if (Forward && added.size() == 1)
+        {
+            assert(removed.size() == 2);
+            const IndexType offsetR1 = TransformedFeatureDimensions * removed[1];
+            auto* columnR1 = reinterpret_cast<const vec_t*>(&featureTransformer.weights[offsetR1]);
+
+            for (IndexType i = 0;
+                 i < TransformedFeatureDimensions * sizeof(WeightType) / sizeof(vec_t); ++i)
+                accOut[i] = vec_sub_16(vec_add_16(accIn[i], columnA0[i]),
+                                       vec_add_16(columnR0[i], columnR1[i]));
+        }
+        else if (Backwards && removed.size() == 1)
+        {
+            assert(added.size() == 2);
+            const IndexType offsetA1 = TransformedFeatureDimensions * added[1];
+            auto* columnA1 = reinterpret_cast<const vec_t*>(&featureTransformer.weights[offsetA1]);
+
+            for (IndexType i = 0;
+                 i < TransformedFeatureDimensions * sizeof(WeightType) / sizeof(vec_t); ++i)
+                accOut[i] = vec_add_16(vec_add_16(accIn[i], columnA0[i]),
+                                       vec_sub_16(columnA1[i], columnR0[i]));
+        }
+        else
+        {
+            assert(added.size() == 2 && removed.size() == 2);
+            const IndexType offsetA1 = TransformedFeatureDimensions * added[1];
+            auto* columnA1 = reinterpret_cast<const vec_t*>(&featureTransformer.weights[offsetA1]);
+            const IndexType offsetR1 = TransformedFeatureDimensions * removed[1];
+            auto* columnR1 = reinterpret_cast<const vec_t*>(&featureTransformer.weights[offsetR1]);
+
+            for (IndexType i = 0;
+                 i < TransformedFeatureDimensions * sizeof(WeightType) / sizeof(vec_t); ++i)
+                accOut[i] = vec_add_16(accIn[i], vec_sub_16(vec_add_16(columnA0[i], columnA1[i]),
+                                                            vec_add_16(columnR0[i], columnR1[i])));
+        }
+
+        auto* accPsqtIn =
+          reinterpret_cast<const psqt_vec_t*>(&(computed.*accPtr).psqtAccumulation[Perspective][0]);
+        auto* accPsqtOut =
+          reinterpret_cast<psqt_vec_t*>(&(target_state.*accPtr).psqtAccumulation[Perspective][0]);
+
+        const IndexType offsetPsqtA0 = PSQTBuckets * added[0];
+        auto*           columnPsqtA0 =
+          reinterpret_cast<const psqt_vec_t*>(&featureTransformer.psqtWeights[offsetPsqtA0]);
+        const IndexType offsetPsqtR0 = PSQTBuckets * removed[0];
+        auto*           columnPsqtR0 =
+          reinterpret_cast<const psqt_vec_t*>(&featureTransformer.psqtWeights[offsetPsqtR0]);
+
+        if ((Forward && removed.size() == 1)
+            || (Backwards && added.size() == 1))  // added.size() == removed.size() == 1
+        {
+            for (std::size_t i = 0; i < PSQTBuckets * sizeof(PSQTWeightType) / sizeof(psqt_vec_t);
+                 ++i)
+                accPsqtOut[i] =
+                  vec_add_psqt_32(vec_sub_psqt_32(accPsqtIn[i], columnPsqtR0[i]), columnPsqtA0[i]);
+        }
+        else if (Forward && added.size() == 1)
+        {
+            const IndexType offsetPsqtR1 = PSQTBuckets * removed[1];
+            auto*           columnPsqtR1 =
+              reinterpret_cast<const psqt_vec_t*>(&featureTransformer.psqtWeights[offsetPsqtR1]);
+
+            for (std::size_t i = 0; i < PSQTBuckets * sizeof(PSQTWeightType) / sizeof(psqt_vec_t);
+                 ++i)
+                accPsqtOut[i] = vec_sub_psqt_32(vec_add_psqt_32(accPsqtIn[i], columnPsqtA0[i]),
+                                                vec_add_psqt_32(columnPsqtR0[i], columnPsqtR1[i]));
+        }
+        else if (Backwards && removed.size() == 1)
+        {
+            const IndexType offsetPsqtA1 = PSQTBuckets * added[1];
+            auto*           columnPsqtA1 =
+              reinterpret_cast<const psqt_vec_t*>(&featureTransformer.psqtWeights[offsetPsqtA1]);
+
+            for (std::size_t i = 0; i < PSQTBuckets * sizeof(PSQTWeightType) / sizeof(psqt_vec_t);
+                 ++i)
+                accPsqtOut[i] = vec_add_psqt_32(vec_add_psqt_32(accPsqtIn[i], columnPsqtA0[i]),
+                                                vec_sub_psqt_32(columnPsqtA1[i], columnPsqtR0[i]));
+        }
+        else
+        {
+            const IndexType offsetPsqtA1 = PSQTBuckets * added[1];
+            auto*           columnPsqtA1 =
+              reinterpret_cast<const psqt_vec_t*>(&featureTransformer.psqtWeights[offsetPsqtA1]);
+            const IndexType offsetPsqtR1 = PSQTBuckets * removed[1];
+            auto*           columnPsqtR1 =
+              reinterpret_cast<const psqt_vec_t*>(&featureTransformer.psqtWeights[offsetPsqtR1]);
+
+            for (std::size_t i = 0; i < PSQTBuckets * sizeof(PSQTWeightType) / sizeof(psqt_vec_t);
+                 ++i)
+                accPsqtOut[i] = vec_add_psqt_32(
+                  accPsqtIn[i], vec_sub_psqt_32(vec_add_psqt_32(columnPsqtA0[i], columnPsqtA1[i]),
+                                                vec_add_psqt_32(columnPsqtR0[i], columnPsqtR1[i])));
+        }
+#else
+        std::memcpy((target_state.*accPtr).accumulation[Perspective],
+                    (computed.*accPtr).accumulation[Perspective],
+                    TransformedFeatureDimensions * sizeof(BiasType));
+        std::memcpy((target_state.*accPtr).psqtAccumulation[Perspective],
+                    (computed.*accPtr).psqtAccumulation[Perspective],
+                    PSQTBuckets * sizeof(PSQTWeightType));
+
+        // Difference calculation for the deactivated features
+        for (const auto index : removed)
+        {
+            const IndexType offset = TransformedFeatureDimensions * index;
+            for (IndexType i = 0; i < TransformedFeatureDimensions; ++i)
+                (target_state.*accPtr).accumulation[Perspective][i] -=
+                  featureTransformer.weights[offset + i];
+
+            for (std::size_t i = 0; i < PSQTBuckets; ++i)
+                (target_state.*accPtr).psqtAccumulation[Perspective][i] -=
+                  featureTransformer.psqtWeights[index * PSQTBuckets + i];
+        }
+
+        // Difference calculation for the activated features
+        for (const auto index : added)
+        {
+            const IndexType offset = TransformedFeatureDimensions * index;
+            for (IndexType i = 0; i < TransformedFeatureDimensions; ++i)
+                (target_state.*accPtr).accumulation[Perspective][i] +=
+                  featureTransformer.weights[offset + i];
+
+            for (std::size_t i = 0; i < PSQTBuckets; ++i)
+                (target_state.*accPtr).psqtAccumulation[Perspective][i] +=
+                  featureTransformer.psqtWeights[index * PSQTBuckets + i];
+        }
+#endif
+    }
+
+    (target_state.*accPtr).computed[Perspective] = true;
+}
+
+template<Color Perspective, IndexType Dimensions, Accumulator<Dimensions> AccumulatorState::*accPtr>
+void update_accumulator_refresh_cache(
+  const FeatureTransformer<Dimensions, accPtr>& featureTransformer,
+  const Position&                               pos,
+  AccumulatorState&                             accumulatorState,
+  AccumulatorCaches::Cache<Dimensions>&         cache) {
+    using Tiling [[maybe_unused]] = SIMDTiling<Dimensions, Dimensions>;
+
+    const Square          ksq   = pos.square<KING>(Perspective);
+    auto&                 entry = cache[ksq][Perspective];
+    FeatureSet::IndexList removed, added;
+
+    for (Color c : {WHITE, BLACK})
+    {
+        for (PieceType pt = PAWN; pt <= KING; ++pt)
+        {
+            const Piece    piece    = make_piece(c, pt);
+            const Bitboard oldBB    = entry.byColorBB[c] & entry.byTypeBB[pt];
+            const Bitboard newBB    = pos.pieces(c, pt);
+            Bitboard       toRemove = oldBB & ~newBB;
+            Bitboard       toAdd    = newBB & ~oldBB;
+
+            while (toRemove)
+            {
+                Square sq = pop_lsb(toRemove);
+                removed.push_back(FeatureSet::make_index<Perspective>(sq, piece, ksq));
+            }
+            while (toAdd)
+            {
+                Square sq = pop_lsb(toAdd);
+                added.push_back(FeatureSet::make_index<Perspective>(sq, piece, ksq));
+            }
+        }
+    }
+
+    auto& accumulator                 = accumulatorState.*accPtr;
+    accumulator.computed[Perspective] = true;
+
+#ifdef VECTOR
+    const bool combineLast3 =
+      std::abs((int) removed.size() - (int) added.size()) == 1 && removed.size() + added.size() > 2;
+    vec_t      acc[Tiling::NumRegs];
+    psqt_vec_t psqt[Tiling::NumPsqtRegs];
+
+    for (IndexType j = 0; j < Dimensions / Tiling::TileHeight; ++j)
+    {
+        auto* accTile =
+          reinterpret_cast<vec_t*>(&accumulator.accumulation[Perspective][j * Tiling::TileHeight]);
+        auto* entryTile = reinterpret_cast<vec_t*>(&entry.accumulation[j * Tiling::TileHeight]);
+
+        for (IndexType k = 0; k < Tiling::NumRegs; ++k)
+            acc[k] = entryTile[k];
+
+        std::size_t i = 0;
+        for (; i < std::min(removed.size(), added.size()) - combineLast3; ++i)
+        {
+            IndexType       indexR  = removed[i];
+            const IndexType offsetR = Dimensions * indexR + j * Tiling::TileHeight;
+            auto* columnR = reinterpret_cast<const vec_t*>(&featureTransformer.weights[offsetR]);
+            IndexType       indexA  = added[i];
+            const IndexType offsetA = Dimensions * indexA + j * Tiling::TileHeight;
+            auto* columnA = reinterpret_cast<const vec_t*>(&featureTransformer.weights[offsetA]);
+
+            for (IndexType k = 0; k < Tiling::NumRegs; ++k)
+                acc[k] = vec_add_16(acc[k], vec_sub_16(columnA[k], columnR[k]));
+        }
+        if (combineLast3)
+        {
+            IndexType       indexR  = removed[i];
+            const IndexType offsetR = Dimensions * indexR + j * Tiling::TileHeight;
+            auto* columnR = reinterpret_cast<const vec_t*>(&featureTransformer.weights[offsetR]);
+            IndexType       indexA  = added[i];
+            const IndexType offsetA = Dimensions * indexA + j * Tiling::TileHeight;
+            auto* columnA = reinterpret_cast<const vec_t*>(&featureTransformer.weights[offsetA]);
+
+            if (removed.size() > added.size())
+            {
+                IndexType       indexR2  = removed[i + 1];
+                const IndexType offsetR2 = Dimensions * indexR2 + j * Tiling::TileHeight;
+                auto*           columnR2 =
+                  reinterpret_cast<const vec_t*>(&featureTransformer.weights[offsetR2]);
+
+                for (IndexType k = 0; k < Tiling::NumRegs; ++k)
+                    acc[k] = vec_sub_16(vec_add_16(acc[k], columnA[k]),
+                                        vec_add_16(columnR[k], columnR2[k]));
+            }
+            else
+            {
+                IndexType       indexA2  = added[i + 1];
+                const IndexType offsetA2 = Dimensions * indexA2 + j * Tiling::TileHeight;
+                auto*           columnA2 =
+                  reinterpret_cast<const vec_t*>(&featureTransformer.weights[offsetA2]);
+
+                for (IndexType k = 0; k < Tiling::NumRegs; ++k)
+                    acc[k] = vec_add_16(vec_sub_16(acc[k], columnR[k]),
+                                        vec_add_16(columnA[k], columnA2[k]));
+            }
+        }
+        else
+        {
+            for (; i < removed.size(); ++i)
+            {
+                IndexType       index  = removed[i];
+                const IndexType offset = Dimensions * index + j * Tiling::TileHeight;
+                auto* column = reinterpret_cast<const vec_t*>(&featureTransformer.weights[offset]);
+
+                for (IndexType k = 0; k < Tiling::NumRegs; ++k)
+                    acc[k] = vec_sub_16(acc[k], column[k]);
+            }
+            for (; i < added.size(); ++i)
+            {
+                IndexType       index  = added[i];
+                const IndexType offset = Dimensions * index + j * Tiling::TileHeight;
+                auto* column = reinterpret_cast<const vec_t*>(&featureTransformer.weights[offset]);
+
+                for (IndexType k = 0; k < Tiling::NumRegs; ++k)
+                    acc[k] = vec_add_16(acc[k], column[k]);
+            }
+        }
+
+        for (IndexType k = 0; k < Tiling::NumRegs; k++)
+            vec_store(&entryTile[k], acc[k]);
+        for (IndexType k = 0; k < Tiling::NumRegs; k++)
+            vec_store(&accTile[k], acc[k]);
+    }
+
+    for (IndexType j = 0; j < PSQTBuckets / Tiling::PsqtTileHeight; ++j)
+    {
+        auto* accTilePsqt = reinterpret_cast<psqt_vec_t*>(
+          &accumulator.psqtAccumulation[Perspective][j * Tiling::PsqtTileHeight]);
+        auto* entryTilePsqt =
+          reinterpret_cast<psqt_vec_t*>(&entry.psqtAccumulation[j * Tiling::PsqtTileHeight]);
+
+        for (std::size_t k = 0; k < Tiling::NumPsqtRegs; ++k)
+            psqt[k] = entryTilePsqt[k];
+
+        for (std::size_t i = 0; i < removed.size(); ++i)
+        {
+            IndexType       index  = removed[i];
+            const IndexType offset = PSQTBuckets * index + j * Tiling::PsqtTileHeight;
+            auto*           columnPsqt =
+              reinterpret_cast<const psqt_vec_t*>(&featureTransformer.psqtWeights[offset]);
+
+            for (std::size_t k = 0; k < Tiling::NumPsqtRegs; ++k)
+                psqt[k] = vec_sub_psqt_32(psqt[k], columnPsqt[k]);
+        }
+        for (std::size_t i = 0; i < added.size(); ++i)
+        {
+            IndexType       index  = added[i];
+            const IndexType offset = PSQTBuckets * index + j * Tiling::PsqtTileHeight;
+            auto*           columnPsqt =
+              reinterpret_cast<const psqt_vec_t*>(&featureTransformer.psqtWeights[offset]);
+
+            for (std::size_t k = 0; k < Tiling::NumPsqtRegs; ++k)
+                psqt[k] = vec_add_psqt_32(psqt[k], columnPsqt[k]);
+        }
+
+        for (std::size_t k = 0; k < Tiling::NumPsqtRegs; ++k)
+            vec_store_psqt(&entryTilePsqt[k], psqt[k]);
+        for (std::size_t k = 0; k < Tiling::NumPsqtRegs; ++k)
+            vec_store_psqt(&accTilePsqt[k], psqt[k]);
+    }
+
+#else
+
+    for (const auto index : removed)
+    {
+        const IndexType offset = Dimensions * index;
+        for (IndexType j = 0; j < Dimensions; ++j)
+            entry.accumulation[j] -= featureTransformer.weights[offset + j];
+
+        for (std::size_t k = 0; k < PSQTBuckets; ++k)
+            entry.psqtAccumulation[k] -= featureTransformer.psqtWeights[index * PSQTBuckets + k];
+    }
+    for (const auto index : added)
+    {
+        const IndexType offset = Dimensions * index;
+        for (IndexType j = 0; j < Dimensions; ++j)
+            entry.accumulation[j] += featureTransformer.weights[offset + j];
+
+        for (std::size_t k = 0; k < PSQTBuckets; ++k)
+            entry.psqtAccumulation[k] += featureTransformer.psqtWeights[index * PSQTBuckets + k];
+    }
+
+    // The accumulator of the refresh entry has been updated.
+    // Now copy its content to the actual accumulator we were refreshing.
+
+    std::memcpy(accumulator.accumulation[Perspective], entry.accumulation,
+                sizeof(BiasType) * Dimensions);
+
+    std::memcpy(accumulator.psqtAccumulation[Perspective], entry.psqtAccumulation,
+                sizeof(int32_t) * PSQTBuckets);
+#endif
+
+    for (Color c : {WHITE, BLACK})
+        entry.byColorBB[c] = pos.pieces(c);
+
+    for (PieceType pt = PAWN; pt <= KING; ++pt)
+        entry.byTypeBB[pt] = pos.pieces(pt);
+}
+
+}
+
+}

src/nnue/nnue_accumulator.h

@@ -1,6 +1,6 @@
 /*
   Stockfish, a UCI chess playing engine derived from Glaurung 2.1
-  Copyright (C) 2004-2024 The Stockfish developers (see AUTHORS file)
+  Copyright (C) 2004-2025 The Stockfish developers (see AUTHORS file)
 
   Stockfish is free software: you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
@@ -21,23 +21,43 @@
 #ifndef NNUE_ACCUMULATOR_H_INCLUDED
 #define NNUE_ACCUMULATOR_H_INCLUDED
 
+#include <array>
+#include <cstddef>
 #include <cstdint>
+#include <cstring>
+#include <vector>
 
+#include "../types.h"
 #include "nnue_architecture.h"
 #include "nnue_common.h"
 
+namespace Stockfish {
+class Position;
+}
+
 namespace Stockfish::Eval::NNUE {
 
 using BiasType       = std::int16_t;
 using PSQTWeightType = std::int32_t;
 using IndexType      = std::uint32_t;
 
+struct Networks;
+
+template<IndexType Size>
+struct alignas(CacheLineSize) Accumulator;
+
+struct AccumulatorState;
+
+template<IndexType                                 TransformedFeatureDimensions,
+         Accumulator<TransformedFeatureDimensions> AccumulatorState::*accPtr>
+class FeatureTransformer;
+
 // Class that holds the result of affine transformation of input features
 template<IndexType Size>
 struct alignas(CacheLineSize) Accumulator {
-    std::int16_t accumulation[COLOR_NB][Size];
-    std::int32_t psqtAccumulation[COLOR_NB][PSQTBuckets];
-    bool         computed[COLOR_NB];
+    std::int16_t               accumulation[COLOR_NB][Size];
+    std::int32_t               psqtAccumulation[COLOR_NB][PSQTBuckets];
+    std::array<bool, COLOR_NB> computed;
 };
 
 
@@ -80,11 +100,6 @@ struct AccumulatorCaches {
                     entry.clear(network.featureTransformer->biases);
         }
 
-        void clear(const BiasType* biases) {
-            for (auto& entry : entries)
-                entry.clear(biases);
-        }
-
         std::array<Entry, COLOR_NB>& operator[](Square sq) { return entries[sq]; }
 
         std::array<std::array<Entry, COLOR_NB>, SQUARE_NB> entries;
@@ -100,6 +115,69 @@ struct AccumulatorCaches {
     Cache<TransformedFeatureDimensionsSmall> small;
 };
 
+
+struct AccumulatorState {
+    Accumulator<TransformedFeatureDimensionsBig>   accumulatorBig;
+    Accumulator<TransformedFeatureDimensionsSmall> accumulatorSmall;
+    DirtyPiece                                     dirtyPiece;
+
+    void reset(const DirtyPiece& dp) noexcept;
+};
+
+
+class AccumulatorStack {
+   public:
+    AccumulatorStack() :
+        m_accumulators(MAX_PLY + 1),
+        m_current_idx{} {}
+
+    [[nodiscard]] const AccumulatorState& latest() const noexcept;
+
+    void
+    reset(const Position& rootPos, const Networks& networks, AccumulatorCaches& caches) noexcept;
+    void push(const DirtyPiece& dirtyPiece) noexcept;
+    void pop() noexcept;
+
+    template<IndexType Dimensions, Accumulator<Dimensions> AccumulatorState::*accPtr>
+    void evaluate(const Position&                               pos,
+                  const FeatureTransformer<Dimensions, accPtr>& featureTransformer,
+                  AccumulatorCaches::Cache<Dimensions>&         cache) noexcept;
+
+   private:
+    [[nodiscard]] AccumulatorState& mut_latest() noexcept;
+
+    template<Color                   Perspective,
+             IndexType               Dimensions,
+             Accumulator<Dimensions> AccumulatorState::*accPtr>
+    void evaluate_side(const Position&                               pos,
+                       const FeatureTransformer<Dimensions, accPtr>& featureTransformer,
+                       AccumulatorCaches::Cache<Dimensions>&         cache) noexcept;
+
+    template<Color                   Perspective,
+             IndexType               Dimensions,
+             Accumulator<Dimensions> AccumulatorState::*accPtr>
+    [[nodiscard]] std::size_t find_last_usable_accumulator() const noexcept;
+
+    template<Color                   Perspective,
+             IndexType               Dimensions,
+             Accumulator<Dimensions> AccumulatorState::*accPtr>
+    void
+    forward_update_incremental(const Position&                               pos,
+                               const FeatureTransformer<Dimensions, accPtr>& featureTransformer,
+                               const std::size_t                             begin) noexcept;
+
+    template<Color                   Perspective,
+             IndexType               Dimensions,
+             Accumulator<Dimensions> AccumulatorState::*accPtr>
+    void
+    backward_update_incremental(const Position&                               pos,
+                                const FeatureTransformer<Dimensions, accPtr>& featureTransformer,
+                                const std::size_t                             end) noexcept;
+
+    std::vector<AccumulatorState> m_accumulators;
+    std::size_t                   m_current_idx;
+};
+
 }  // namespace Stockfish::Eval::NNUE
 
 #endif  // NNUE_ACCUMULATOR_H_INCLUDED

src/nnue/nnue_architecture.h

@@ -1,6 +1,6 @@
 /*
   Stockfish, a UCI chess playing engine derived from Glaurung 2.1
-  Copyright (C) 2004-2024 The Stockfish developers (see AUTHORS file)
+  Copyright (C) 2004-2025 The Stockfish developers (see AUTHORS file)
 
   Stockfish is free software: you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by

src/nnue/nnue_common.h

@@ -1,6 +1,6 @@
 /*
   Stockfish, a UCI chess playing engine derived from Glaurung 2.1
-  Copyright (C) 2004-2024 The Stockfish developers (see AUTHORS file)
+  Copyright (C) 2004-2025 The Stockfish developers (see AUTHORS file)
 
   Stockfish is free software: you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
@@ -279,6 +279,11 @@ inline void write_leb_128(std::ostream& stream, const IntType* values, std::size
     flush();
 }
 
+enum IncUpdateDirection {
+    FORWARD,
+    BACKWARDS
+};
+
 }  // namespace Stockfish::Eval::NNUE
 
 #endif  // #ifndef NNUE_COMMON_H_INCLUDED

src/nnue/nnue_feature_transformer.h

@@ -1,6 +1,6 @@
 /*
   Stockfish, a UCI chess playing engine derived from Glaurung 2.1
-  Copyright (C) 2004-2024 The Stockfish developers (see AUTHORS file)
+  Copyright (C) 2004-2025 The Stockfish developers (see AUTHORS file)
 
   Stockfish is free software: you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
@@ -22,11 +22,9 @@
 #define NNUE_FEATURE_TRANSFORMER_H_INCLUDED
 
 #include <algorithm>
-#include <cassert>
 #include <cstdint>
 #include <cstring>
 #include <iosfwd>
-#include <utility>
 
 #include "../position.h"
 #include "../types.h"
@@ -145,11 +143,51 @@ using psqt_vec_t = int32x4_t;
 
 #endif
 
+// Returns the inverse of a permutation
+template<std::size_t Len>
+constexpr std::array<std::size_t, Len>
+invert_permutation(const std::array<std::size_t, Len>& order) {
+    std::array<std::size_t, Len> inverse{};
+    for (std::size_t i = 0; i < order.size(); i++)
+        inverse[order[i]] = i;
+    return inverse;
+}
 
+// Divide a byte region of size TotalSize to chunks of size
+// BlockSize, and permute the blocks by a given order
+template<std::size_t BlockSize, typename T, std::size_t N, std::size_t OrderSize>
+void permute(T (&data)[N], const std::array<std::size_t, OrderSize>& order) {
+    constexpr std::size_t TotalSize = N * sizeof(T);
+
+    static_assert(TotalSize % (BlockSize * OrderSize) == 0,
+                  "ChunkSize * OrderSize must perfectly divide TotalSize");
+
+    constexpr std::size_t ProcessChunkSize = BlockSize * OrderSize;
+
+    std::array<std::byte, ProcessChunkSize> buffer{};
+
+    std::byte* const bytes = reinterpret_cast<std::byte*>(data);
+
+    for (std::size_t i = 0; i < TotalSize; i += ProcessChunkSize)
+    {
+        std::byte* const values = &bytes[i];
+
+        for (std::size_t j = 0; j < OrderSize; j++)
+        {
+            auto* const buffer_chunk = &buffer[j * BlockSize];
+            auto* const value_chunk  = &values[order[j] * BlockSize];
+
+            std::copy(value_chunk, value_chunk + BlockSize, buffer_chunk);
+        }
+
+        std::copy(std::begin(buffer), std::end(buffer), values);
+    }
+}
+
+// Compute optimal SIMD register count for feature transformer accumulation.
+template<IndexType TransformedFeatureWidth, IndexType HalfDimensions>
+class SIMDTiling {
 #ifdef VECTOR
-
-    // Compute optimal SIMD register count for feature transformer accumulation.
-
     // We use __m* types as template arguments, which causes GCC to emit warnings
     // about losing some attribute information. This is irrelevant to us as we
     // only take their size, so the following pragma are harmless.
@@ -158,55 +196,56 @@ using psqt_vec_t = int32x4_t;
         #pragma GCC diagnostic ignored "-Wignored-attributes"
     #endif
 
-template<typename SIMDRegisterType, typename LaneType, int NumLanes, int MaxRegisters>
-static constexpr int BestRegisterCount() {
-    #define RegisterSize sizeof(SIMDRegisterType)
-    #define LaneSize sizeof(LaneType)
+    template<typename SIMDRegisterType, typename LaneType, int NumLanes, int MaxRegisters>
+    static constexpr int BestRegisterCount() {
+        constexpr std::size_t RegisterSize = sizeof(SIMDRegisterType);
+        constexpr std::size_t LaneSize     = sizeof(LaneType);
 
-    static_assert(RegisterSize >= LaneSize);
-    static_assert(MaxRegisters <= NumRegistersSIMD);
-    static_assert(MaxRegisters > 0);
-    static_assert(NumRegistersSIMD > 0);
-    static_assert(RegisterSize % LaneSize == 0);
-    static_assert((NumLanes * LaneSize) % RegisterSize == 0);
+        static_assert(RegisterSize >= LaneSize);
+        static_assert(MaxRegisters <= NumRegistersSIMD);
+        static_assert(MaxRegisters > 0);
+        static_assert(NumRegistersSIMD > 0);
+        static_assert(RegisterSize % LaneSize == 0);
+        static_assert((NumLanes * LaneSize) % RegisterSize == 0);
 
-    const int ideal = (NumLanes * LaneSize) / RegisterSize;
-    if (ideal <= MaxRegisters)
-        return ideal;
+        const int ideal = (NumLanes * LaneSize) / RegisterSize;
+        if (ideal <= MaxRegisters)
+            return ideal;
 
-    // Look for the largest divisor of the ideal register count that is smaller than MaxRegisters
-    for (int divisor = MaxRegisters; divisor > 1; --divisor)
-        if (ideal % divisor == 0)
-            return divisor;
+        // Look for the largest divisor of the ideal register count that is smaller than MaxRegisters
+        for (int divisor = MaxRegisters; divisor > 1; --divisor)
+            if (ideal % divisor == 0)
+                return divisor;
+
+        return 1;
+    }
 
-    return 1;
-}
     #if defined(__GNUC__)
         #pragma GCC diagnostic pop
     #endif
-#endif
 
-
-// Input feature converter
-template<IndexType                                 TransformedFeatureDimensions,
-         Accumulator<TransformedFeatureDimensions> StateInfo::*accPtr>
-class FeatureTransformer {
-
-    // Number of output dimensions for one side
-    static constexpr IndexType HalfDimensions = TransformedFeatureDimensions;
-
-   private:
-#ifdef VECTOR
+   public:
     static constexpr int NumRegs =
-      BestRegisterCount<vec_t, WeightType, TransformedFeatureDimensions, NumRegistersSIMD>();
+      BestRegisterCount<vec_t, WeightType, TransformedFeatureWidth, NumRegistersSIMD>();
     static constexpr int NumPsqtRegs =
       BestRegisterCount<psqt_vec_t, PSQTWeightType, PSQTBuckets, NumRegistersSIMD>();
 
     static constexpr IndexType TileHeight     = NumRegs * sizeof(vec_t) / 2;
     static constexpr IndexType PsqtTileHeight = NumPsqtRegs * sizeof(psqt_vec_t) / 4;
+
     static_assert(HalfDimensions % TileHeight == 0, "TileHeight must divide HalfDimensions");
     static_assert(PSQTBuckets % PsqtTileHeight == 0, "PsqtTileHeight must divide PSQTBuckets");
 #endif
+};
+
+
+// Input feature converter
+template<IndexType                                 TransformedFeatureDimensions,
+         Accumulator<TransformedFeatureDimensions> AccumulatorState::*accPtr>
+class FeatureTransformer {
+
+    // Number of output dimensions for one side
+    static constexpr IndexType HalfDimensions = TransformedFeatureDimensions;
 
    public:
     // Output type
@@ -219,76 +258,54 @@ class FeatureTransformer {
     // Size of forward propagation buffer
     static constexpr std::size_t BufferSize = OutputDimensions * sizeof(OutputType);
 
+    // Store the order by which 128-bit blocks of a 1024-bit data must
+    // be permuted so that calling packus on adjacent vectors of 16-bit
+    // integers loaded from the data results in the pre-permutation order
+    static constexpr auto PackusEpi16Order = []() -> std::array<std::size_t, 8> {
+#if defined(USE_AVX512)
+        // _mm512_packus_epi16 after permutation:
+        // |   0   |   2   |   4   |   6   | // Vector 0
+        // |   1   |   3   |   5   |   7   | // Vector 1
+        // | 0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 | // Packed Result
+        return {0, 2, 4, 6, 1, 3, 5, 7};
+#elif defined(USE_AVX2)
+        // _mm256_packus_epi16 after permutation:
+        // |   0   |   2   |  |   4   |   6   | // Vector 0, 2
+        // |   1   |   3   |  |   5   |   7   | // Vector 1, 3
+        // | 0 | 1 | 2 | 3 |  | 4 | 5 | 6 | 7 | // Packed Result
+        return {0, 2, 1, 3, 4, 6, 5, 7};
+#else
+        return {0, 1, 2, 3, 4, 5, 6, 7};
+#endif
+    }();
+
+    static constexpr auto InversePackusEpi16Order = invert_permutation(PackusEpi16Order);
+
     // Hash value embedded in the evaluation file
     static constexpr std::uint32_t get_hash_value() {
         return FeatureSet::HashValue ^ (OutputDimensions * 2);
     }
 
-    static constexpr void order_packs([[maybe_unused]] uint64_t* v) {
-#if defined(USE_AVX512)  // _mm512_packs_epi16 ordering
-        uint64_t tmp0 = v[2], tmp1 = v[3];
-        v[2] = v[8], v[3] = v[9];
-        v[8] = v[4], v[9] = v[5];
-        v[4] = tmp0, v[5] = tmp1;
-        tmp0 = v[6], tmp1 = v[7];
-        v[6] = v[10], v[7] = v[11];
-        v[10] = v[12], v[11] = v[13];
-        v[12] = tmp0, v[13] = tmp1;
-#elif defined(USE_AVX2)  // _mm256_packs_epi16 ordering
-        std::swap(v[2], v[4]);
-        std::swap(v[3], v[5]);
-#endif
+    void permute_weights() {
+        permute<16>(biases, PackusEpi16Order);
+        permute<16>(weights, PackusEpi16Order);
     }
 
-    static constexpr void inverse_order_packs([[maybe_unused]] uint64_t* v) {
-#if defined(USE_AVX512)  // Inverse _mm512_packs_epi16 ordering
-        uint64_t tmp0 = v[2], tmp1 = v[3];
-        v[2] = v[4], v[3] = v[5];
-        v[4] = v[8], v[5] = v[9];
-        v[8] = tmp0, v[9] = tmp1;
-        tmp0 = v[6], tmp1 = v[7];
-        v[6] = v[12], v[7] = v[13];
-        v[12] = v[10], v[13] = v[11];
-        v[10] = tmp0, v[11] = tmp1;
-#elif defined(USE_AVX2)  // Inverse _mm256_packs_epi16 ordering
-        std::swap(v[2], v[4]);
-        std::swap(v[3], v[5]);
-#endif
+    void unpermute_weights() {
+        permute<16>(biases, InversePackusEpi16Order);
+        permute<16>(weights, InversePackusEpi16Order);
     }
 
-    void permute_weights([[maybe_unused]] void (*order_fn)(uint64_t*)) const {
-#if defined(USE_AVX2)
-    #if defined(USE_AVX512)
-        constexpr IndexType di = 16;
-    #else
-        constexpr IndexType di = 8;
-    #endif
-        uint64_t* b = reinterpret_cast<uint64_t*>(const_cast<BiasType*>(&biases[0]));
-        for (IndexType i = 0; i < HalfDimensions * sizeof(BiasType) / sizeof(uint64_t); i += di)
-            order_fn(&b[i]);
-
+    inline void scale_weights(bool read) {
         for (IndexType j = 0; j < InputDimensions; ++j)
         {
-            uint64_t* w =
-              reinterpret_cast<uint64_t*>(const_cast<WeightType*>(&weights[j * HalfDimensions]));
-            for (IndexType i = 0; i < HalfDimensions * sizeof(WeightType) / sizeof(uint64_t);
-                 i += di)
-                order_fn(&w[i]);
-        }
-#endif
-    }
-
-    inline void scale_weights(bool read) const {
-        for (IndexType j = 0; j < InputDimensions; ++j)
-        {
-            WeightType* w = const_cast<WeightType*>(&weights[j * HalfDimensions]);
+            WeightType* w = &weights[j * HalfDimensions];
             for (IndexType i = 0; i < HalfDimensions; ++i)
                 w[i] = read ? w[i] * 2 : w[i] / 2;
         }
 
-        BiasType* b = const_cast<BiasType*>(biases);
         for (IndexType i = 0; i < HalfDimensions; ++i)
-            b[i] = read ? b[i] * 2 : b[i] / 2;
+            biases[i] = read ? biases[i] * 2 : biases[i] / 2;
     }
 
     // Read network parameters
@@ -298,41 +315,43 @@ class FeatureTransformer {
         read_leb_128<WeightType>(stream, weights, HalfDimensions * InputDimensions);
         read_leb_128<PSQTWeightType>(stream, psqtWeights, PSQTBuckets * InputDimensions);
 
-        permute_weights(inverse_order_packs);
+        permute_weights();
         scale_weights(true);
         return !stream.fail();
     }
 
     // Write network parameters
-    bool write_parameters(std::ostream& stream) const {
+    bool write_parameters(std::ostream& stream) {
 
-        permute_weights(order_packs);
+        unpermute_weights();
         scale_weights(false);
 
         write_leb_128<BiasType>(stream, biases, HalfDimensions);
         write_leb_128<WeightType>(stream, weights, HalfDimensions * InputDimensions);
         write_leb_128<PSQTWeightType>(stream, psqtWeights, PSQTBuckets * InputDimensions);
 
-        permute_weights(inverse_order_packs);
+        permute_weights();
         scale_weights(true);
         return !stream.fail();
     }
 
     // Convert input features
     std::int32_t transform(const Position&                           pos,
+                           AccumulatorStack&                         accumulatorStack,
                            AccumulatorCaches::Cache<HalfDimensions>* cache,
                            OutputType*                               output,
                            int                                       bucket) const {
-        update_accumulator<WHITE>(pos, cache);
-        update_accumulator<BLACK>(pos, cache);
+
+        accumulatorStack.evaluate(pos, *this, *cache);
+        const auto& accumulatorState = accumulatorStack.latest();
 
         const Color perspectives[2]  = {pos.side_to_move(), ~pos.side_to_move()};
-        const auto& psqtAccumulation = (pos.state()->*accPtr).psqtAccumulation;
+        const auto& psqtAccumulation = (accumulatorState.*accPtr).psqtAccumulation;
         const auto  psqt =
           (psqtAccumulation[perspectives[0]][bucket] - psqtAccumulation[perspectives[1]][bucket])
           / 2;
 
-        const auto& accumulation = (pos.state()->*accPtr).accumulation;
+        const auto& accumulation = (accumulatorState.*accPtr).accumulation;
 
         for (IndexType p = 0; p < 2; ++p)
         {
@@ -445,480 +464,6 @@ class FeatureTransformer {
         return psqt;
     }  // end of function transform()
 
-    void hint_common_access(const Position&                           pos,
-                            AccumulatorCaches::Cache<HalfDimensions>* cache) const {
-        hint_common_access_for_perspective<WHITE>(pos, cache);
-        hint_common_access_for_perspective<BLACK>(pos, cache);
-    }
-
-   private:
-    template<Color Perspective>
-    [[nodiscard]] std::pair<StateInfo*, StateInfo*>
-    try_find_computed_accumulator(const Position& pos) const {
-        // Look for a usable accumulator of an earlier position. We keep track
-        // of the estimated gain in terms of features to be added/subtracted.
-        StateInfo *st = pos.state(), *next = nullptr;
-        int        gain = FeatureSet::refresh_cost(pos);
-        while (st->previous && !(st->*accPtr).computed[Perspective])
-        {
-            // This governs when a full feature refresh is needed and how many
-            // updates are better than just one full refresh.
-            if (FeatureSet::requires_refresh(st, Perspective)
-                || (gain -= FeatureSet::update_cost(st) + 1) < 0)
-                break;
-            next = st;
-            st   = st->previous;
-        }
-        return {st, next};
-    }
-
-    // NOTE: The parameter states_to_update is an array of position states.
-    //       All states must be sequential, that is states_to_update[i] must
-    //       either be reachable by repeatedly applying ->previous from
-    //       states_to_update[i+1], and computed_st must be reachable by
-    //       repeatedly applying ->previous on states_to_update[0].
-    template<Color Perspective, size_t N>
-    void update_accumulator_incremental(const Position& pos,
-                                        StateInfo*      computed_st,
-                                        StateInfo*      states_to_update[N]) const {
-        static_assert(N > 0);
-        assert([&]() {
-            for (size_t i = 0; i < N; ++i)
-            {
-                if (states_to_update[i] == nullptr)
-                    return false;
-            }
-            return true;
-        }());
-
-#ifdef VECTOR
-        // Gcc-10.2 unnecessarily spills AVX2 registers if this array
-        // is defined in the VECTOR code below, once in each branch.
-        vec_t      acc[NumRegs];
-        psqt_vec_t psqt[NumPsqtRegs];
-#endif
-
-        // Update incrementally going back through states_to_update.
-        // Gather all features to be updated.
-        const Square ksq = pos.square<KING>(Perspective);
-
-        // The size must be enough to contain the largest possible update.
-        // That might depend on the feature set and generally relies on the
-        // feature set's update cost calculation to be correct and never allow
-        // updates with more added/removed features than MaxActiveDimensions.
-        FeatureSet::IndexList removed[N], added[N];
-
-        for (int i = N - 1; i >= 0; --i)
-        {
-            (states_to_update[i]->*accPtr).computed[Perspective] = true;
-
-            const StateInfo* end_state = i == 0 ? computed_st : states_to_update[i - 1];
-
-            for (StateInfo* st2 = states_to_update[i]; st2 != end_state; st2 = st2->previous)
-                FeatureSet::append_changed_indices<Perspective>(ksq, st2->dirtyPiece, removed[i],
-                                                                added[i]);
-        }
-
-        StateInfo* st = computed_st;
-
-        // Now update the accumulators listed in states_to_update[],
-        // where the last element is a sentinel.
-#ifdef VECTOR
-
-        if (N == 1 && (removed[0].size() == 1 || removed[0].size() == 2) && added[0].size() == 1)
-        {
-            assert(states_to_update[0]);
-
-            auto accIn =
-              reinterpret_cast<const vec_t*>(&(st->*accPtr).accumulation[Perspective][0]);
-            auto accOut = reinterpret_cast<vec_t*>(
-              &(states_to_update[0]->*accPtr).accumulation[Perspective][0]);
-
-            const IndexType offsetR0 = HalfDimensions * removed[0][0];
-            auto            columnR0 = reinterpret_cast<const vec_t*>(&weights[offsetR0]);
-            const IndexType offsetA  = HalfDimensions * added[0][0];
-            auto            columnA  = reinterpret_cast<const vec_t*>(&weights[offsetA]);
-
-            if (removed[0].size() == 1)
-            {
-                for (IndexType k = 0; k < HalfDimensions * sizeof(std::int16_t) / sizeof(vec_t);
-                     ++k)
-                    accOut[k] = vec_add_16(vec_sub_16(accIn[k], columnR0[k]), columnA[k]);
-            }
-            else
-            {
-                const IndexType offsetR1 = HalfDimensions * removed[0][1];
-                auto            columnR1 = reinterpret_cast<const vec_t*>(&weights[offsetR1]);
-
-                for (IndexType k = 0; k < HalfDimensions * sizeof(std::int16_t) / sizeof(vec_t);
-                     ++k)
-                    accOut[k] = vec_sub_16(vec_add_16(accIn[k], columnA[k]),
-                                           vec_add_16(columnR0[k], columnR1[k]));
-            }
-
-            auto accPsqtIn =
-              reinterpret_cast<const psqt_vec_t*>(&(st->*accPtr).psqtAccumulation[Perspective][0]);
-            auto accPsqtOut = reinterpret_cast<psqt_vec_t*>(
-              &(states_to_update[0]->*accPtr).psqtAccumulation[Perspective][0]);
-
-            const IndexType offsetPsqtR0 = PSQTBuckets * removed[0][0];
-            auto columnPsqtR0 = reinterpret_cast<const psqt_vec_t*>(&psqtWeights[offsetPsqtR0]);
-            const IndexType offsetPsqtA = PSQTBuckets * added[0][0];
-            auto columnPsqtA = reinterpret_cast<const psqt_vec_t*>(&psqtWeights[offsetPsqtA]);
-
-            if (removed[0].size() == 1)
-            {
-                for (std::size_t k = 0; k < PSQTBuckets * sizeof(std::int32_t) / sizeof(psqt_vec_t);
-                     ++k)
-                    accPsqtOut[k] = vec_add_psqt_32(vec_sub_psqt_32(accPsqtIn[k], columnPsqtR0[k]),
-                                                    columnPsqtA[k]);
-            }
-            else
-            {
-                const IndexType offsetPsqtR1 = PSQTBuckets * removed[0][1];
-                auto columnPsqtR1 = reinterpret_cast<const psqt_vec_t*>(&psqtWeights[offsetPsqtR1]);
-
-                for (std::size_t k = 0; k < PSQTBuckets * sizeof(std::int32_t) / sizeof(psqt_vec_t);
-                     ++k)
-                    accPsqtOut[k] =
-                      vec_sub_psqt_32(vec_add_psqt_32(accPsqtIn[k], columnPsqtA[k]),
-                                      vec_add_psqt_32(columnPsqtR0[k], columnPsqtR1[k]));
-            }
-        }
-        else
-        {
-            for (IndexType j = 0; j < HalfDimensions / TileHeight; ++j)
-            {
-                // Load accumulator
-                auto accTileIn = reinterpret_cast<const vec_t*>(
-                  &(st->*accPtr).accumulation[Perspective][j * TileHeight]);
-                for (IndexType k = 0; k < NumRegs; ++k)
-                    acc[k] = vec_load(&accTileIn[k]);
-
-                for (IndexType i = 0; i < N; ++i)
-                {
-                    // Difference calculation for the deactivated features
-                    for (const auto index : removed[i])
-                    {
-                        const IndexType offset = HalfDimensions * index + j * TileHeight;
-                        auto            column = reinterpret_cast<const vec_t*>(&weights[offset]);
-                        for (IndexType k = 0; k < NumRegs; ++k)
-                            acc[k] = vec_sub_16(acc[k], column[k]);
-                    }
-
-                    // Difference calculation for the activated features
-                    for (const auto index : added[i])
-                    {
-                        const IndexType offset = HalfDimensions * index + j * TileHeight;
-                        auto            column = reinterpret_cast<const vec_t*>(&weights[offset]);
-                        for (IndexType k = 0; k < NumRegs; ++k)
-                            acc[k] = vec_add_16(acc[k], column[k]);
-                    }
-
-                    // Store accumulator
-                    auto accTileOut = reinterpret_cast<vec_t*>(
-                      &(states_to_update[i]->*accPtr).accumulation[Perspective][j * TileHeight]);
-                    for (IndexType k = 0; k < NumRegs; ++k)
-                        vec_store(&accTileOut[k], acc[k]);
-                }
-            }
-
-            for (IndexType j = 0; j < PSQTBuckets / PsqtTileHeight; ++j)
-            {
-                // Load accumulator
-                auto accTilePsqtIn = reinterpret_cast<const psqt_vec_t*>(
-                  &(st->*accPtr).psqtAccumulation[Perspective][j * PsqtTileHeight]);
-                for (std::size_t k = 0; k < NumPsqtRegs; ++k)
-                    psqt[k] = vec_load_psqt(&accTilePsqtIn[k]);
-
-                for (IndexType i = 0; i < N; ++i)
-                {
-                    // Difference calculation for the deactivated features
-                    for (const auto index : removed[i])
-                    {
-                        const IndexType offset = PSQTBuckets * index + j * PsqtTileHeight;
-                        auto columnPsqt = reinterpret_cast<const psqt_vec_t*>(&psqtWeights[offset]);
-                        for (std::size_t k = 0; k < NumPsqtRegs; ++k)
-                            psqt[k] = vec_sub_psqt_32(psqt[k], columnPsqt[k]);
-                    }
-
-                    // Difference calculation for the activated features
-                    for (const auto index : added[i])
-                    {
-                        const IndexType offset = PSQTBuckets * index + j * PsqtTileHeight;
-                        auto columnPsqt = reinterpret_cast<const psqt_vec_t*>(&psqtWeights[offset]);
-                        for (std::size_t k = 0; k < NumPsqtRegs; ++k)
-                            psqt[k] = vec_add_psqt_32(psqt[k], columnPsqt[k]);
-                    }
-
-                    // Store accumulator
-                    auto accTilePsqtOut = reinterpret_cast<psqt_vec_t*>(
-                      &(states_to_update[i]->*accPtr)
-                         .psqtAccumulation[Perspective][j * PsqtTileHeight]);
-                    for (std::size_t k = 0; k < NumPsqtRegs; ++k)
-                        vec_store_psqt(&accTilePsqtOut[k], psqt[k]);
-                }
-            }
-        }
-#else
-        for (IndexType i = 0; i < N; ++i)
-        {
-            std::memcpy((states_to_update[i]->*accPtr).accumulation[Perspective],
-                        (st->*accPtr).accumulation[Perspective], HalfDimensions * sizeof(BiasType));
-
-            for (std::size_t k = 0; k < PSQTBuckets; ++k)
-                (states_to_update[i]->*accPtr).psqtAccumulation[Perspective][k] =
-                  (st->*accPtr).psqtAccumulation[Perspective][k];
-
-            st = states_to_update[i];
-
-            // Difference calculation for the deactivated features
-            for (const auto index : removed[i])
-            {
-                const IndexType offset = HalfDimensions * index;
-                for (IndexType j = 0; j < HalfDimensions; ++j)
-                    (st->*accPtr).accumulation[Perspective][j] -= weights[offset + j];
-
-                for (std::size_t k = 0; k < PSQTBuckets; ++k)
-                    (st->*accPtr).psqtAccumulation[Perspective][k] -=
-                      psqtWeights[index * PSQTBuckets + k];
-            }
-
-            // Difference calculation for the activated features
-            for (const auto index : added[i])
-            {
-                const IndexType offset = HalfDimensions * index;
-                for (IndexType j = 0; j < HalfDimensions; ++j)
-                    (st->*accPtr).accumulation[Perspective][j] += weights[offset + j];
-
-                for (std::size_t k = 0; k < PSQTBuckets; ++k)
-                    (st->*accPtr).psqtAccumulation[Perspective][k] +=
-                      psqtWeights[index * PSQTBuckets + k];
-            }
-        }
-#endif
-    }
-
-    template<Color Perspective>
-    void update_accumulator_refresh_cache(const Position&                           pos,
-                                          AccumulatorCaches::Cache<HalfDimensions>* cache) const {
-        assert(cache != nullptr);
-
-        Square                ksq   = pos.square<KING>(Perspective);
-        auto&                 entry = (*cache)[ksq][Perspective];
-        FeatureSet::IndexList removed, added;
-
-        for (Color c : {WHITE, BLACK})
-        {
-            for (PieceType pt = PAWN; pt <= KING; ++pt)
-            {
-                const Piece    piece    = make_piece(c, pt);
-                const Bitboard oldBB    = entry.byColorBB[c] & entry.byTypeBB[pt];
-                const Bitboard newBB    = pos.pieces(c, pt);
-                Bitboard       toRemove = oldBB & ~newBB;
-                Bitboard       toAdd    = newBB & ~oldBB;
-
-                while (toRemove)
-                {
-                    Square sq = pop_lsb(toRemove);
-                    removed.push_back(FeatureSet::make_index<Perspective>(sq, piece, ksq));
-                }
-                while (toAdd)
-                {
-                    Square sq = pop_lsb(toAdd);
-                    added.push_back(FeatureSet::make_index<Perspective>(sq, piece, ksq));
-                }
-            }
-        }
-
-        auto& accumulator                 = pos.state()->*accPtr;
-        accumulator.computed[Perspective] = true;
-
-#ifdef VECTOR
-        vec_t      acc[NumRegs];
-        psqt_vec_t psqt[NumPsqtRegs];
-
-        for (IndexType j = 0; j < HalfDimensions / TileHeight; ++j)
-        {
-            auto accTile =
-              reinterpret_cast<vec_t*>(&accumulator.accumulation[Perspective][j * TileHeight]);
-            auto entryTile = reinterpret_cast<vec_t*>(&entry.accumulation[j * TileHeight]);
-
-            for (IndexType k = 0; k < NumRegs; ++k)
-                acc[k] = entryTile[k];
-
-            int i = 0;
-            for (; i < int(std::min(removed.size(), added.size())); ++i)
-            {
-                IndexType       indexR  = removed[i];
-                const IndexType offsetR = HalfDimensions * indexR + j * TileHeight;
-                auto            columnR = reinterpret_cast<const vec_t*>(&weights[offsetR]);
-                IndexType       indexA  = added[i];
-                const IndexType offsetA = HalfDimensions * indexA + j * TileHeight;
-                auto            columnA = reinterpret_cast<const vec_t*>(&weights[offsetA]);
-
-                for (unsigned k = 0; k < NumRegs; ++k)
-                    acc[k] = vec_add_16(acc[k], vec_sub_16(columnA[k], columnR[k]));
-            }
-            for (; i < int(removed.size()); ++i)
-            {
-                IndexType       index  = removed[i];
-                const IndexType offset = HalfDimensions * index + j * TileHeight;
-                auto            column = reinterpret_cast<const vec_t*>(&weights[offset]);
-
-                for (unsigned k = 0; k < NumRegs; ++k)
-                    acc[k] = vec_sub_16(acc[k], column[k]);
-            }
-            for (; i < int(added.size()); ++i)
-            {
-                IndexType       index  = added[i];
-                const IndexType offset = HalfDimensions * index + j * TileHeight;
-                auto            column = reinterpret_cast<const vec_t*>(&weights[offset]);
-
-                for (unsigned k = 0; k < NumRegs; ++k)
-                    acc[k] = vec_add_16(acc[k], column[k]);
-            }
-
-            for (IndexType k = 0; k < NumRegs; k++)
-                vec_store(&entryTile[k], acc[k]);
-            for (IndexType k = 0; k < NumRegs; k++)
-                vec_store(&accTile[k], acc[k]);
-        }
-
-        for (IndexType j = 0; j < PSQTBuckets / PsqtTileHeight; ++j)
-        {
-            auto accTilePsqt = reinterpret_cast<psqt_vec_t*>(
-              &accumulator.psqtAccumulation[Perspective][j * PsqtTileHeight]);
-            auto entryTilePsqt =
-              reinterpret_cast<psqt_vec_t*>(&entry.psqtAccumulation[j * PsqtTileHeight]);
-
-            for (std::size_t k = 0; k < NumPsqtRegs; ++k)
-                psqt[k] = entryTilePsqt[k];
-
-            for (int i = 0; i < int(removed.size()); ++i)
-            {
-                IndexType       index  = removed[i];
-                const IndexType offset = PSQTBuckets * index + j * PsqtTileHeight;
-                auto columnPsqt        = reinterpret_cast<const psqt_vec_t*>(&psqtWeights[offset]);
-
-                for (std::size_t k = 0; k < NumPsqtRegs; ++k)
-                    psqt[k] = vec_sub_psqt_32(psqt[k], columnPsqt[k]);
-            }
-            for (int i = 0; i < int(added.size()); ++i)
-            {
-                IndexType       index  = added[i];
-                const IndexType offset = PSQTBuckets * index + j * PsqtTileHeight;
-                auto columnPsqt        = reinterpret_cast<const psqt_vec_t*>(&psqtWeights[offset]);
-
-                for (std::size_t k = 0; k < NumPsqtRegs; ++k)
-                    psqt[k] = vec_add_psqt_32(psqt[k], columnPsqt[k]);
-            }
-
-            for (std::size_t k = 0; k < NumPsqtRegs; ++k)
-                vec_store_psqt(&entryTilePsqt[k], psqt[k]);
-            for (std::size_t k = 0; k < NumPsqtRegs; ++k)
-                vec_store_psqt(&accTilePsqt[k], psqt[k]);
-        }
-
-#else
-
-        for (const auto index : removed)
-        {
-            const IndexType offset = HalfDimensions * index;
-            for (IndexType j = 0; j < HalfDimensions; ++j)
-                entry.accumulation[j] -= weights[offset + j];
-
-            for (std::size_t k = 0; k < PSQTBuckets; ++k)
-                entry.psqtAccumulation[k] -= psqtWeights[index * PSQTBuckets + k];
-        }
-        for (const auto index : added)
-        {
-            const IndexType offset = HalfDimensions * index;
-            for (IndexType j = 0; j < HalfDimensions; ++j)
-                entry.accumulation[j] += weights[offset + j];
-
-            for (std::size_t k = 0; k < PSQTBuckets; ++k)
-                entry.psqtAccumulation[k] += psqtWeights[index * PSQTBuckets + k];
-        }
-
-        // The accumulator of the refresh entry has been updated.
-        // Now copy its content to the actual accumulator we were refreshing.
-
-        std::memcpy(accumulator.accumulation[Perspective], entry.accumulation,
-                    sizeof(BiasType) * HalfDimensions);
-
-        std::memcpy(accumulator.psqtAccumulation[Perspective], entry.psqtAccumulation,
-                    sizeof(int32_t) * PSQTBuckets);
-#endif
-
-        for (Color c : {WHITE, BLACK})
-            entry.byColorBB[c] = pos.pieces(c);
-
-        for (PieceType pt = PAWN; pt <= KING; ++pt)
-            entry.byTypeBB[pt] = pos.pieces(pt);
-    }
-
-    template<Color Perspective>
-    void hint_common_access_for_perspective(const Position&                           pos,
-                                            AccumulatorCaches::Cache<HalfDimensions>* cache) const {
-
-        // Works like update_accumulator, but performs less work.
-        // Updates ONLY the accumulator for pos.
-
-        // Look for a usable accumulator of an earlier position. We keep track
-        // of the estimated gain in terms of features to be added/subtracted.
-        // Fast early exit.
-        if ((pos.state()->*accPtr).computed[Perspective])
-            return;
-
-        auto [oldest_st, _] = try_find_computed_accumulator<Perspective>(pos);
-
-        if ((oldest_st->*accPtr).computed[Perspective])
-        {
-            // Only update current position accumulator to minimize work
-            StateInfo* states_to_update[1] = {pos.state()};
-            update_accumulator_incremental<Perspective, 1>(pos, oldest_st, states_to_update);
-        }
-        else
-            update_accumulator_refresh_cache<Perspective>(pos, cache);
-    }
-
-    template<Color Perspective>
-    void update_accumulator(const Position&                           pos,
-                            AccumulatorCaches::Cache<HalfDimensions>* cache) const {
-
-        auto [oldest_st, next] = try_find_computed_accumulator<Perspective>(pos);
-
-        if ((oldest_st->*accPtr).computed[Perspective])
-        {
-            if (next == nullptr)
-                return;
-
-            // Now update the accumulators listed in states_to_update[], where
-            // the last element is a sentinel. Currently we update two accumulators:
-            //     1. for the current position
-            //     2. the next accumulator after the computed one
-            // The heuristic may change in the future.
-            if (next == pos.state())
-            {
-                StateInfo* states_to_update[1] = {next};
-
-                update_accumulator_incremental<Perspective, 1>(pos, oldest_st, states_to_update);
-            }
-            else
-            {
-                StateInfo* states_to_update[2] = {next, pos.state()};
-
-                update_accumulator_incremental<Perspective, 2>(pos, oldest_st, states_to_update);
-            }
-        }
-        else
-            update_accumulator_refresh_cache<Perspective>(pos, cache);
-    }
-
-    template<IndexType Size>
-    friend struct AccumulatorCaches::Cache;
-
     alignas(CacheLineSize) BiasType biases[HalfDimensions];
     alignas(CacheLineSize) WeightType weights[HalfDimensions * InputDimensions];
     alignas(CacheLineSize) PSQTWeightType psqtWeights[InputDimensions * PSQTBuckets];

src/nnue/nnue_misc.cpp

@@ -1,6 +1,6 @@
 /*
   Stockfish, a UCI chess playing engine derived from Glaurung 2.1
-  Copyright (C) 2004-2024 The Stockfish developers (see AUTHORS file)
+  Copyright (C) 2004-2025 The Stockfish developers (see AUTHORS file)
 
   Stockfish is free software: you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
@@ -30,7 +30,6 @@
 #include <string_view>
 #include <tuple>
 
-#include "../evaluate.h"
 #include "../position.h"
 #include "../types.h"
 #include "../uci.h"
@@ -43,15 +42,6 @@ namespace Stockfish::Eval::NNUE {
 constexpr std::string_view PieceToChar(" PNBRQK  pnbrqk");
 
 
-void hint_common_parent_position(const Position&    pos,
-                                 const Networks&    networks,
-                                 AccumulatorCaches& caches) {
-    if (Eval::use_smallnet(pos))
-        networks.small.hint_common_access(pos, &caches.small);
-    else
-        networks.big.hint_common_access(pos, &caches.big);
-}
-
 namespace {
 // Converts a Value into (centi)pawns and writes it in a buffer.
 // The buffer must have capacity for at least 5 chars.
@@ -126,13 +116,16 @@ trace(Position& pos, const Eval::NNUE::Networks& networks, Eval::NNUE::Accumulat
         board[y][x] = board[y][x + 8] = board[y + 3][x + 8] = board[y + 3][x] = '+';
         if (pc != NO_PIECE)
             board[y + 1][x + 4] = PieceToChar[pc];
-        if (value != VALUE_NONE)
+        if (is_valid(value))
             format_cp_compact(value, &board[y + 2][x + 2], pos);
     };
 
+    AccumulatorStack accumulators;
+    accumulators.reset(pos, networks, caches);
+
     // We estimate the value of each piece by doing a differential evaluation from
     // the current base eval, simulating the removal of the piece from its square.
-    auto [psqt, positional] = networks.big.evaluate(pos, &caches.big);
+    auto [psqt, positional] = networks.big.evaluate(pos, accumulators, &caches.big);
     Value base              = psqt + positional;
     base                    = pos.side_to_move() == WHITE ? base : -base;
 
@@ -145,18 +138,15 @@ trace(Position& pos, const Eval::NNUE::Networks& networks, Eval::NNUE::Accumulat
 
             if (pc != NO_PIECE && type_of(pc) != KING)
             {
-                auto st = pos.state();
-
                 pos.remove_piece(sq);
-                st->accumulatorBig.computed[WHITE] = st->accumulatorBig.computed[BLACK] = false;
 
-                std::tie(psqt, positional) = networks.big.evaluate(pos, &caches.big);
+                accumulators.reset(pos, networks, caches);
+                std::tie(psqt, positional) = networks.big.evaluate(pos, accumulators, &caches.big);
                 Value eval                 = psqt + positional;
                 eval                       = pos.side_to_move() == WHITE ? eval : -eval;
                 v                          = base - eval;
 
                 pos.put_piece(pc, sq);
-                st->accumulatorBig.computed[WHITE] = st->accumulatorBig.computed[BLACK] = false;
             }
 
             writeSquare(f, r, pc, v);
@@ -167,7 +157,8 @@ trace(Position& pos, const Eval::NNUE::Networks& networks, Eval::NNUE::Accumulat
         ss << board[row] << '\n';
     ss << '\n';
 
-    auto t = networks.big.trace_evaluate(pos, &caches.big);
+    accumulators.reset(pos, networks, caches);
+    auto t = networks.big.trace_evaluate(pos, accumulators, &caches.big);
 
     ss << " NNUE network contributions "
        << (pos.side_to_move() == WHITE ? "(White to move)" : "(Black to move)") << std::endl

src/nnue/nnue_misc.h

@@ -1,6 +1,6 @@
 /*
   Stockfish, a UCI chess playing engine derived from Glaurung 2.1
-  Copyright (C) 2004-2024 The Stockfish developers (see AUTHORS file)
+  Copyright (C) 2004-2025 The Stockfish developers (see AUTHORS file)
 
   Stockfish is free software: you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
@@ -54,9 +54,6 @@ struct Networks;
 struct AccumulatorCaches;
 
 std::string trace(Position& pos, const Networks& networks, AccumulatorCaches& caches);
-void        hint_common_parent_position(const Position&    pos,
-                                        const Networks&    networks,
-                                        AccumulatorCaches& caches);
 
 }  // namespace Stockfish::Eval::NNUE
 }  // namespace Stockfish

src/numa.h

@@ -1,6 +1,6 @@
 /*
   Stockfish, a UCI chess playing engine derived from Glaurung 2.1
-  Copyright (C) 2004-2024 The Stockfish developers (see AUTHORS file)
+  Copyright (C) 2004-2025 The Stockfish developers (see AUTHORS file)
 
   Stockfish is free software: you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
@@ -23,6 +23,7 @@
 #include <atomic>
 #include <cstdint>
 #include <cstdlib>
+#include <functional>
 #include <iostream>
 #include <limits>
 #include <map>
@@ -653,7 +654,7 @@ class NumaConfig {
         NumaIndex n = 0;
         for (auto&& nodeStr : split(s, ":"))
         {
-            auto indices = indices_from_shortened_string(nodeStr);
+            auto indices = indices_from_shortened_string(std::string(nodeStr));
             if (!indices.empty())
             {
                 for (auto idx : indices)
@@ -1015,7 +1016,7 @@ class NumaConfig {
         if (s.empty())
             return indices;
 
-        for (const std::string& ss : split(s, ","))
+        for (const auto& ss : split(s, ","))
         {
             if (ss.empty())
                 continue;
@@ -1023,13 +1024,13 @@ class NumaConfig {
             auto parts = split(ss, "-");
             if (parts.size() == 1)
             {
-                const CpuIndex c = CpuIndex{str_to_size_t(parts[0])};
+                const CpuIndex c = CpuIndex{str_to_size_t(std::string(parts[0]))};
                 indices.emplace_back(c);
             }
             else if (parts.size() == 2)
             {
-                const CpuIndex cfirst = CpuIndex{str_to_size_t(parts[0])};
-                const CpuIndex clast  = CpuIndex{str_to_size_t(parts[1])};
+                const CpuIndex cfirst = CpuIndex{str_to_size_t(std::string(parts[0]))};
+                const CpuIndex clast  = CpuIndex{str_to_size_t(std::string(parts[1]))};
                 for (size_t c = cfirst; c <= clast; ++c)
                 {
                     indices.emplace_back(c);

src/perft.h

@@ -1,6 +1,6 @@
 /*
   Stockfish, a UCI chess playing engine derived from Glaurung 2.1
-  Copyright (C) 2004-2024 The Stockfish developers (see AUTHORS file)
+  Copyright (C) 2004-2025 The Stockfish developers (see AUTHORS file)
 
   Stockfish is free software: you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
@@ -34,7 +34,6 @@ template<bool Root>
 uint64_t perft(Position& pos, Depth depth) {
 
     StateInfo st;
-    ASSERT_ALIGNED(&st, Eval::NNUE::CacheLineSize);
 
     uint64_t   cnt, nodes = 0;
     const bool leaf = (depth == 2);

src/position.cpp

@@ -1,6 +1,6 @@
 /*
   Stockfish, a UCI chess playing engine derived from Glaurung 2.1
-  Copyright (C) 2004-2024 The Stockfish developers (see AUTHORS file)
+  Copyright (C) 2004-2025 The Stockfish developers (see AUTHORS file)
 
   Stockfish is free software: you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
@@ -34,7 +34,6 @@
 #include "bitboard.h"
 #include "misc.h"
 #include "movegen.h"
-#include "nnue/nnue_common.h"
 #include "syzygy/tbprobe.h"
 #include "tt.h"
 #include "uci.h"
@@ -83,7 +82,6 @@ std::ostream& operator<<(std::ostream& os, const Position& pos) {
     if (int(Tablebases::MaxCardinality) >= popcount(pos.pieces()) && !pos.can_castle(ANY_CASTLING))
     {
         StateInfo st;
-        ASSERT_ALIGNED(&st, Eval::NNUE::CacheLineSize);
 
         Position p;
         p.set(pos.fen(), pos.is_chess960(), &st);
@@ -119,6 +117,9 @@ void Position::init() {
     for (Piece pc : Pieces)
         for (Square s = SQ_A1; s <= SQ_H8; ++s)
             Zobrist::psq[pc][s] = rng.rand<Key>();
+    // pawns on these squares will promote
+    std::fill_n(Zobrist::psq[W_PAWN] + SQ_A8, 8, 0);
+    std::fill_n(Zobrist::psq[B_PAWN], 8, 0);
 
     for (File f = FILE_A; f <= FILE_H; ++f)
         Zobrist::enpassant[f] = rng.rand<Key>();
@@ -334,8 +335,10 @@ void Position::set_check_info() const {
 // The function is only used when a new position is set up
 void Position::set_state() const {
 
-    st->key = st->materialKey  = 0;
-    st->pawnKey                = Zobrist::noPawns;
+    st->key = st->materialKey = 0;
+    st->minorPieceKey         = 0;
+    st->nonPawnKey[WHITE] = st->nonPawnKey[BLACK] = 0;
+    st->pawnKey                                   = Zobrist::noPawns;
     st->nonPawnMaterial[WHITE] = st->nonPawnMaterial[BLACK] = VALUE_ZERO;
     st->checkersBB = attackers_to(square<KING>(sideToMove)) & pieces(~sideToMove);
 
@@ -350,8 +353,18 @@ void Position::set_state() const {
         if (type_of(pc) == PAWN)
             st->pawnKey ^= Zobrist::psq[pc][s];
 
-        else if (type_of(pc) != KING)
-            st->nonPawnMaterial[color_of(pc)] += PieceValue[pc];
+        else
+        {
+            st->nonPawnKey[color_of(pc)] ^= Zobrist::psq[pc][s];
+
+            if (type_of(pc) != KING)
+            {
+                st->nonPawnMaterial[color_of(pc)] += PieceValue[pc];
+
+                if (type_of(pc) <= BISHOP)
+                    st->minorPieceKey ^= Zobrist::psq[pc][s];
+            }
+        }
     }
 
     if (st->epSquare != SQ_NONE)
@@ -364,7 +377,7 @@ void Position::set_state() const {
 
     for (Piece pc : Pieces)
         for (int cnt = 0; cnt < pieceCount[pc]; ++cnt)
-            st->materialKey ^= Zobrist::psq[pc][cnt];
+            st->materialKey ^= Zobrist::psq[pc][8 + cnt];
 }
 
 
@@ -472,14 +485,23 @@ void Position::update_slider_blockers(Color c) const {
 // Slider attacks use the occupied bitboard to indicate occupancy.
 Bitboard Position::attackers_to(Square s, Bitboard occupied) const {
 
-    return (pawn_attacks_bb(BLACK, s) & pieces(WHITE, PAWN))
-         | (pawn_attacks_bb(WHITE, s) & pieces(BLACK, PAWN))
-         | (attacks_bb<KNIGHT>(s) & pieces(KNIGHT))
-         | (attacks_bb<ROOK>(s, occupied) & pieces(ROOK, QUEEN))
+    return (attacks_bb<ROOK>(s, occupied) & pieces(ROOK, QUEEN))
          | (attacks_bb<BISHOP>(s, occupied) & pieces(BISHOP, QUEEN))
-         | (attacks_bb<KING>(s) & pieces(KING));
+         | (pawn_attacks_bb(BLACK, s) & pieces(WHITE, PAWN))
+         | (pawn_attacks_bb(WHITE, s) & pieces(BLACK, PAWN))
+         | (attacks_bb<KNIGHT>(s) & pieces(KNIGHT)) | (attacks_bb<KING>(s) & pieces(KING));
 }
 
+bool Position::attackers_to_exist(Square s, Bitboard occupied, Color c) const {
+
+    return ((attacks_bb<ROOK>(s) & pieces(c, ROOK, QUEEN))
+            && (attacks_bb<ROOK>(s, occupied) & pieces(c, ROOK, QUEEN)))
+        || ((attacks_bb<BISHOP>(s) & pieces(c, BISHOP, QUEEN))
+            && (attacks_bb<BISHOP>(s, occupied) & pieces(c, BISHOP, QUEEN)))
+        || (((pawn_attacks_bb(~c, s) & pieces(PAWN)) | (attacks_bb<KNIGHT>(s) & pieces(KNIGHT))
+             | (attacks_bb<KING>(s) & pieces(KING)))
+            & pieces(c));
+}
 
 // Tests whether a pseudo-legal move is legal
 bool Position::legal(Move m) const {
@@ -521,7 +543,7 @@ bool Position::legal(Move m) const {
         Direction step = to > from ? WEST : EAST;
 
         for (Square s = to; s != from; s += step)
-            if (attackers_to(s) & pieces(~us))
+            if (attackers_to_exist(s, pieces(), ~us))
                 return false;
 
         // In case of Chess960, verify if the Rook blocks some checks.
@@ -532,11 +554,11 @@ bool Position::legal(Move m) const {
     // If the moving piece is a king, check whether the destination square is
     // attacked by the opponent.
     if (type_of(piece_on(from)) == KING)
-        return !(attackers_to(to, pieces() ^ from) & pieces(~us));
+        return !(attackers_to_exist(to, pieces() ^ from, ~us));
 
     // A non-king move is legal if and only if it is not pinned or it
     // is moving along the ray towards or away from the king.
-    return !(blockers_for_king(us) & from) || aligned(from, to, square<KING>(us));
+    return !(blockers_for_king(us) & from) || line_bb(from, to) & pieces(us, KING);
 }
 
 
@@ -601,7 +623,7 @@ bool Position::pseudo_legal(const Move m) const {
         }
         // In case of king moves under check we have to remove the king so as to catch
         // invalid moves like b1a1 when opposite queen is on c1.
-        else if (attackers_to(to, pieces() ^ from) & pieces(~us))
+        else if (attackers_to_exist(to, pieces() ^ from, ~us))
             return false;
     }
 
@@ -624,7 +646,7 @@ bool Position::gives_check(Move m) const {
 
     // Is there a discovered check?
     if (blockers_for_king(~sideToMove) & from)
-        return !aligned(from, to, square<KING>(~sideToMove)) || m.type_of() == CASTLING;
+        return !(line_bb(from, to) & pieces(~sideToMove, KING)) || m.type_of() == CASTLING;
 
     switch (m.type_of())
     {
@@ -632,7 +654,7 @@ bool Position::gives_check(Move m) const {
         return false;
 
     case PROMOTION :
-        return attacks_bb(m.promotion_type(), to, pieces() ^ from) & square<KING>(~sideToMove);
+        return attacks_bb(m.promotion_type(), to, pieces() ^ from) & pieces(~sideToMove, KING);
 
     // En passant capture with check? We have already handled the case of direct
     // checks and ordinary discovered check, so the only case we need to handle
@@ -659,7 +681,12 @@ bool Position::gives_check(Move m) const {
 // Makes a move, and saves all information necessary
 // to a StateInfo object. The move is assumed to be legal. Pseudo-legal
 // moves should be filtered out before this function is called.
-void Position::do_move(Move m, StateInfo& newSt, bool givesCheck) {
+// If a pointer to the TT table is passed, the entry for the new position
+// will be prefetched
+DirtyPiece Position::do_move(Move                      m,
+                             StateInfo&                newSt,
+                             bool                      givesCheck,
+                             const TranspositionTable* tt = nullptr) {
 
     assert(m.is_ok());
     assert(&newSt != st);
@@ -671,6 +698,7 @@ void Position::do_move(Move m, StateInfo& newSt, bool givesCheck) {
     // our state pointer to point to the new (ready to be updated) state.
     std::memcpy(&newSt, st, offsetof(StateInfo, key));
     newSt.previous = st;
+    st->next       = &newSt;
     st             = &newSt;
 
     // Increment ply counters. In particular, rule50 will be reset to zero later on
@@ -679,11 +707,7 @@ void Position::do_move(Move m, StateInfo& newSt, bool givesCheck) {
     ++st->rule50;
     ++st->pliesFromNull;
 
-    // Used by NNUE
-    st->accumulatorBig.computed[WHITE]     = st->accumulatorBig.computed[BLACK] =
-      st->accumulatorSmall.computed[WHITE] = st->accumulatorSmall.computed[BLACK] = false;
-
-    auto& dp     = st->dirtyPiece;
+    DirtyPiece dp;
     dp.dirty_num = 1;
 
     Color  us       = sideToMove;
@@ -703,9 +727,10 @@ void Position::do_move(Move m, StateInfo& newSt, bool givesCheck) {
         assert(captured == make_piece(us, ROOK));
 
         Square rfrom, rto;
-        do_castling<true>(us, from, to, rfrom, rto);
+        do_castling<true>(us, from, to, rfrom, rto, &dp);
 
         k ^= Zobrist::psq[captured][rfrom] ^ Zobrist::psq[captured][rto];
+        st->nonPawnKey[us] ^= Zobrist::psq[captured][rfrom] ^ Zobrist::psq[captured][rto];
         captured = NO_PIECE;
     }
 
@@ -731,7 +756,13 @@ void Position::do_move(Move m, StateInfo& newSt, bool givesCheck) {
             st->pawnKey ^= Zobrist::psq[captured][capsq];
         }
         else
+        {
             st->nonPawnMaterial[them] -= PieceValue[captured];
+            st->nonPawnKey[them] ^= Zobrist::psq[captured][capsq];
+
+            if (type_of(captured) <= BISHOP)
+                st->minorPieceKey ^= Zobrist::psq[captured][capsq];
+        }
 
         dp.dirty_num = 2;  // 1 piece moved, 1 piece captured
         dp.piece[1]  = captured;
@@ -742,7 +773,7 @@ void Position::do_move(Move m, StateInfo& newSt, bool givesCheck) {
         remove_piece(capsq);
 
         k ^= Zobrist::psq[captured][capsq];
-        st->materialKey ^= Zobrist::psq[captured][pieceCount[captured]];
+        st->materialKey ^= Zobrist::psq[captured][8 + pieceCount[captured]];
 
         // Reset rule 50 counter
         st->rule50 = 0;
@@ -789,7 +820,8 @@ void Position::do_move(Move m, StateInfo& newSt, bool givesCheck) {
 
         else if (m.type_of() == PROMOTION)
         {
-            Piece promotion = make_piece(us, m.promotion_type());
+            Piece     promotion     = make_piece(us, m.promotion_type());
+            PieceType promotionType = type_of(promotion);
 
             assert(relative_rank(us, to) == RANK_8);
             assert(type_of(promotion) >= KNIGHT && type_of(promotion) <= QUEEN);
@@ -805,10 +837,13 @@ void Position::do_move(Move m, StateInfo& newSt, bool givesCheck) {
             dp.dirty_num++;
 
             // Update hash keys
-            k ^= Zobrist::psq[pc][to] ^ Zobrist::psq[promotion][to];
-            st->pawnKey ^= Zobrist::psq[pc][to];
-            st->materialKey ^=
-              Zobrist::psq[promotion][pieceCount[promotion] - 1] ^ Zobrist::psq[pc][pieceCount[pc]];
+            // Zobrist::psq[pc][to] is zero, so we don't need to clear it
+            k ^= Zobrist::psq[promotion][to];
+            st->materialKey ^= Zobrist::psq[promotion][8 + pieceCount[promotion] - 1]
+                             ^ Zobrist::psq[pc][8 + pieceCount[pc]];
+
+            if (promotionType <= BISHOP)
+                st->minorPieceKey ^= Zobrist::psq[promotion][to];
 
             // Update material
             st->nonPawnMaterial[us] += PieceValue[promotion];
@@ -821,11 +856,21 @@ void Position::do_move(Move m, StateInfo& newSt, bool givesCheck) {
         st->rule50 = 0;
     }
 
-    // Set capture piece
-    st->capturedPiece = captured;
+    else
+    {
+        st->nonPawnKey[us] ^= Zobrist::psq[pc][from] ^ Zobrist::psq[pc][to];
+
+        if (type_of(pc) <= BISHOP)
+            st->minorPieceKey ^= Zobrist::psq[pc][from] ^ Zobrist::psq[pc][to];
+    }
 
     // Update the key with the final value
     st->key = k;
+    if (tt)
+        prefetch(tt->first_entry(key()));
+
+    // Set capture piece
+    st->capturedPiece = captured;
 
     // Calculate checkers bitboard (if move gives check)
     st->checkersBB = givesCheck ? attackers_to(square<KING>(them)) & pieces(us) : 0;
@@ -855,6 +900,8 @@ void Position::do_move(Move m, StateInfo& newSt, bool givesCheck) {
     }
 
     assert(pos_is_ok());
+
+    return dp;
 }
 
 
@@ -924,23 +971,25 @@ void Position::undo_move(Move m) {
 // Helper used to do/undo a castling move. This is a bit
 // tricky in Chess960 where from/to squares can overlap.
 template<bool Do>
-void Position::do_castling(Color us, Square from, Square& to, Square& rfrom, Square& rto) {
+void Position::do_castling(
+  Color us, Square from, Square& to, Square& rfrom, Square& rto, DirtyPiece* const dp) {
 
     bool kingSide = to > from;
     rfrom         = to;  // Castling is encoded as "king captures friendly rook"
     rto           = relative_square(us, kingSide ? SQ_F1 : SQ_D1);
     to            = relative_square(us, kingSide ? SQ_G1 : SQ_C1);
 
+    assert(!Do || dp);
+
     if (Do)
     {
-        auto& dp     = st->dirtyPiece;
-        dp.piece[0]  = make_piece(us, KING);
-        dp.from[0]   = from;
-        dp.to[0]     = to;
-        dp.piece[1]  = make_piece(us, ROOK);
-        dp.from[1]   = rfrom;
-        dp.to[1]     = rto;
-        dp.dirty_num = 2;
+        dp->piece[0]  = make_piece(us, KING);
+        dp->from[0]   = from;
+        dp->to[0]     = to;
+        dp->piece[1]  = make_piece(us, ROOK);
+        dp->from[1]   = rfrom;
+        dp->to[1]     = rto;
+        dp->dirty_num = 2;
     }
 
     // Remove both pieces first since squares could overlap in Chess960
@@ -955,21 +1004,17 @@ void Position::do_castling(Color us, Square from, Square& to, Square& rfrom, Squ
 
 // Used to do a "null move": it flips
 // the side to move without executing any move on the board.
-void Position::do_null_move(StateInfo& newSt, TranspositionTable& tt) {
+void Position::do_null_move(StateInfo& newSt, const TranspositionTable& tt) {
 
     assert(!checkers());
     assert(&newSt != st);
 
-    std::memcpy(&newSt, st, offsetof(StateInfo, accumulatorBig));
+    std::memcpy(&newSt, st, sizeof(StateInfo));
 
     newSt.previous = st;
+    st->next       = &newSt;
     st             = &newSt;
 
-    st->dirtyPiece.dirty_num               = 0;
-    st->dirtyPiece.piece[0]                = NO_PIECE;  // Avoid checks in UpdateAccumulator()
-    st->accumulatorBig.computed[WHITE]     = st->accumulatorBig.computed[BLACK] =
-      st->accumulatorSmall.computed[WHITE] = st->accumulatorSmall.computed[BLACK] = false;
-
     if (st->epSquare != SQ_NONE)
     {
         st->key ^= Zobrist::enpassant[file_of(st->epSquare)];
@@ -977,7 +1022,6 @@ void Position::do_null_move(StateInfo& newSt, TranspositionTable& tt) {
     }
 
     st->key ^= Zobrist::side;
-    ++st->rule50;
     prefetch(tt.first_entry(key()));
 
     st->pliesFromNull = 0;
@@ -1002,26 +1046,6 @@ void Position::undo_null_move() {
 }
 
 
-// Computes the new hash key after the given move. Needed
-// for speculative prefetch. It doesn't recognize special moves like castling,
-// en passant and promotions.
-Key Position::key_after(Move m) const {
-
-    Square from     = m.from_sq();
-    Square to       = m.to_sq();
-    Piece  pc       = piece_on(from);
-    Piece  captured = piece_on(to);
-    Key    k        = st->key ^ Zobrist::side;
-
-    if (captured)
-        k ^= Zobrist::psq[captured][to];
-
-    k ^= Zobrist::psq[pc][to] ^ Zobrist::psq[pc][from];
-
-    return (captured || type_of(pc) == PAWN) ? k : adjust_key50<true>(k);
-}
-
-
 // Tests if the SEE (Static Exchange Evaluation)
 // value of move is greater or equal to the given threshold. We'll use an
 // algorithm similar to alpha-beta pruning with a null window.
@@ -1109,8 +1133,9 @@ bool Position::see_ge(Move m, int threshold) const {
 
         else if ((bb = stmAttackers & pieces(QUEEN)))
         {
-            if ((swap = QueenValue - swap) < res)
-                break;
+            swap = QueenValue - swap;
+            //  implies that the previous recapture was done by a higher rated piece than a Queen (King is excluded)
+            assert(swap >= res);
             occupied ^= least_significant_square_bb(bb);
 
             attackers |= (attacks_bb<BISHOP>(to, occupied) & pieces(BISHOP, QUEEN))
@@ -1133,11 +1158,12 @@ bool Position::is_draw(int ply) const {
     if (st->rule50 > 99 && (!checkers() || MoveList<LEGAL>(*this).size()))
         return true;
 
-    // Return a draw score if a position repeats once earlier but strictly
-    // after the root, or repeats twice before or at the root.
-    return st->repetition && st->repetition < ply;
+    return is_repetition(ply);
 }
 
+// Return a draw score if a position repeats once earlier but strictly
+// after the root, or repeats twice before or at the root.
+bool Position::is_repetition(int ply) const { return st->repetition && st->repetition < ply; }
 
 // Tests whether there has been at least one repetition
 // of positions since the last capture or pawn move.
@@ -1253,7 +1279,7 @@ bool Position::pos_is_ok() const {
         return true;
 
     if (pieceCount[W_KING] != 1 || pieceCount[B_KING] != 1
-        || attackers_to(square<KING>(~sideToMove)) & pieces(sideToMove))
+        || attackers_to_exist(square<KING>(~sideToMove), pieces(), sideToMove))
         assert(0 && "pos_is_ok: Kings");
 
     if ((pieces(PAWN) & (Rank1BB | Rank8BB)) || pieceCount[W_PAWN] > 8 || pieceCount[B_PAWN] > 8)

src/position.h

@@ -1,6 +1,6 @@
 /*
   Stockfish, a UCI chess playing engine derived from Glaurung 2.1
-  Copyright (C) 2004-2024 The Stockfish developers (see AUTHORS file)
+  Copyright (C) 2004-2025 The Stockfish developers (see AUTHORS file)
 
   Stockfish is free software: you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
@@ -26,8 +26,6 @@
 #include <string>
 
 #include "bitboard.h"
-#include "nnue/nnue_accumulator.h"
-#include "nnue/nnue_architecture.h"
 #include "types.h"
 
 namespace Stockfish {
@@ -43,6 +41,8 @@ struct StateInfo {
     // Copied when making a move
     Key    materialKey;
     Key    pawnKey;
+    Key    minorPieceKey;
+    Key    nonPawnKey[COLOR_NB];
     Value  nonPawnMaterial[COLOR_NB];
     int    castlingRights;
     int    rule50;
@@ -53,16 +53,12 @@ struct StateInfo {
     Key        key;
     Bitboard   checkersBB;
     StateInfo* previous;
+    StateInfo* next;
     Bitboard   blockersForKing[COLOR_NB];
     Bitboard   pinners[COLOR_NB];
     Bitboard   checkSquares[PIECE_TYPE_NB];
     Piece      capturedPiece;
     int        repetition;
-
-    // Used by NNUE
-    Eval::NNUE::Accumulator<Eval::NNUE::TransformedFeatureDimensionsBig>   accumulatorBig;
-    Eval::NNUE::Accumulator<Eval::NNUE::TransformedFeatureDimensionsSmall> accumulatorSmall;
-    DirtyPiece                                                             dirtyPiece;
 };
 
 
@@ -122,6 +118,7 @@ class Position {
     // Attacks to/from a given square
     Bitboard attackers_to(Square s) const;
     Bitboard attackers_to(Square s, Bitboard occupied) const;
+    bool     attackers_to_exist(Square s, Bitboard occupied, Color c) const;
     void     update_slider_blockers(Color c) const;
     template<PieceType Pt>
     Bitboard attacks_by(Color c) const;
@@ -136,26 +133,28 @@ class Position {
     Piece captured_piece() const;
 
     // Doing and undoing moves
-    void do_move(Move m, StateInfo& newSt);
-    void do_move(Move m, StateInfo& newSt, bool givesCheck);
-    void undo_move(Move m);
-    void do_null_move(StateInfo& newSt, TranspositionTable& tt);
-    void undo_null_move();
+    void       do_move(Move m, StateInfo& newSt, const TranspositionTable* tt);
+    DirtyPiece do_move(Move m, StateInfo& newSt, bool givesCheck, const TranspositionTable* tt);
+    void       undo_move(Move m);
+    void       do_null_move(StateInfo& newSt, const TranspositionTable& tt);
+    void       undo_null_move();
 
     // Static Exchange Evaluation
     bool see_ge(Move m, int threshold = 0) const;
 
     // Accessing hash keys
     Key key() const;
-    Key key_after(Move m) const;
     Key material_key() const;
     Key pawn_key() const;
+    Key minor_piece_key() const;
+    Key non_pawn_key(Color c) const;
 
     // Other properties of the position
     Color side_to_move() const;
     int   game_ply() const;
     bool  is_chess960() const;
     bool  is_draw(int ply) const;
+    bool  is_repetition(int ply) const;
     bool  upcoming_repetition(int ply) const;
     bool  has_repeated() const;
     int   rule50_count() const;
@@ -181,7 +180,12 @@ class Position {
     // Other helpers
     void move_piece(Square from, Square to);
     template<bool Do>
-    void do_castling(Color us, Square from, Square& to, Square& rfrom, Square& rto);
+    void do_castling(Color             us,
+                     Square            from,
+                     Square&           to,
+                     Square&           rfrom,
+                     Square&           rto,
+                     DirtyPiece* const dp = nullptr);
     template<bool AfterMove>
     Key adjust_key50(Key k) const;
 
@@ -297,6 +301,10 @@ inline Key Position::pawn_key() const { return st->pawnKey; }
 
 inline Key Position::material_key() const { return st->materialKey; }
 
+inline Key Position::minor_piece_key() const { return st->minorPieceKey; }
+
+inline Key Position::non_pawn_key(Color c) const { return st->nonPawnKey[c]; }
+
 inline Value Position::non_pawn_material(Color c) const { return st->nonPawnMaterial[c]; }
 
 inline Value Position::non_pawn_material() const {
@@ -355,7 +363,9 @@ inline void Position::move_piece(Square from, Square to) {
     board[to]   = pc;
 }
 
-inline void Position::do_move(Move m, StateInfo& newSt) { do_move(m, newSt, gives_check(m)); }
+inline void Position::do_move(Move m, StateInfo& newSt, const TranspositionTable* tt = nullptr) {
+    do_move(m, newSt, gives_check(m), tt);
+}
 
 inline StateInfo* Position::state() const { return st; }
 

src/score.cpp

@@ -1,6 +1,6 @@
 /*
   Stockfish, a UCI chess playing engine derived from Glaurung 2.1
-  Copyright (C) 2004-2024 The Stockfish developers (see AUTHORS file)
+  Copyright (C) 2004-2025 The Stockfish developers (see AUTHORS file)
 
   Stockfish is free software: you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
@@ -29,7 +29,7 @@ namespace Stockfish {
 Score::Score(Value v, const Position& pos) {
     assert(-VALUE_INFINITE < v && v < VALUE_INFINITE);
 
-    if (std::abs(v) < VALUE_TB_WIN_IN_MAX_PLY)
+    if (!is_decisive(v))
     {
         score = InternalUnits{UCIEngine::to_cp(v, pos)};
     }

src/score.h

@@ -1,6 +1,6 @@
 /*
   Stockfish, a UCI chess playing engine derived from Glaurung 2.1
-  Copyright (C) 2004-2024 The Stockfish developers (see AUTHORS file)
+  Copyright (C) 2004-2025 The Stockfish developers (see AUTHORS file)
 
   Stockfish is free software: you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by

src/search.h

@@ -1,6 +1,6 @@
 /*
   Stockfish, a UCI chess playing engine derived from Glaurung 2.1
-  Copyright (C) 2004-2024 The Stockfish developers (see AUTHORS file)
+  Copyright (C) 2004-2025 The Stockfish developers (see AUTHORS file)
 
   Stockfish is free software: you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
@@ -31,8 +31,8 @@
 #include <string_view>
 #include <vector>
 
+#include "history.h"
 #include "misc.h"
-#include "movepick.h"
 #include "nnue/network.h"
 #include "nnue/nnue_accumulator.h"
 #include "numa.h"
@@ -61,18 +61,21 @@ namespace Search {
 // shallower and deeper in the tree during the search. Each search thread has
 // its own array of Stack objects, indexed by the current ply.
 struct Stack {
-    Move*           pv;
-    PieceToHistory* continuationHistory;
-    int             ply;
-    Move            currentMove;
-    Move            excludedMove;
-    Value           staticEval;
-    int             statScore;
-    int             moveCount;
-    bool            inCheck;
-    bool            ttPv;
-    bool            ttHit;
-    int             cutoffCnt;
+    Move*                       pv;
+    PieceToHistory*             continuationHistory;
+    CorrectionHistory<PieceTo>* continuationCorrectionHistory;
+    int                         ply;
+    Move                        currentMove;
+    Move                        excludedMove;
+    Value                       staticEval;
+    int                         statScore;
+    int                         moveCount;
+    bool                        inCheck;
+    bool                        ttPv;
+    bool                        ttHit;
+    int                         cutoffCnt;
+    int                         reduction;
+    bool                        isTTMove;
 };
 
 
@@ -90,15 +93,16 @@ struct RootMove {
         return m.score != score ? m.score < score : m.previousScore < previousScore;
     }
 
-    uint64_t          effort          = 0;
-    Value             score           = -VALUE_INFINITE;
-    Value             previousScore   = -VALUE_INFINITE;
-    Value             averageScore    = -VALUE_INFINITE;
-    Value             uciScore        = -VALUE_INFINITE;
-    bool              scoreLowerbound = false;
-    bool              scoreUpperbound = false;
-    int               selDepth        = 0;
-    int               tbRank          = 0;
+    uint64_t          effort           = 0;
+    Value             score            = -VALUE_INFINITE;
+    Value             previousScore    = -VALUE_INFINITE;
+    Value             averageScore     = -VALUE_INFINITE;
+    Value             meanSquaredScore = -VALUE_INFINITE * VALUE_INFINITE;
+    Value             uciScore         = -VALUE_INFINITE;
+    bool              scoreLowerbound  = false;
+    bool              scoreUpperbound  = false;
+    int               selDepth         = 0;
+    int               tbRank           = 0;
     Value             tbScore;
     std::vector<Move> pv;
 };
@@ -124,7 +128,6 @@ struct LimitsType {
     int                      movestogo, depth, mate, perft, infinite;
     uint64_t                 nodes;
     bool                     ponderMode;
-    Square                   capSq;
 };
 
 
@@ -277,15 +280,27 @@ class Worker {
     void ensure_network_replicated();
 
     // Public because they need to be updatable by the stats
-    ButterflyHistory      mainHistory;
+    ButterflyHistory mainHistory;
+    LowPlyHistory    lowPlyHistory;
+
     CapturePieceToHistory captureHistory;
     ContinuationHistory   continuationHistory[2][2];
     PawnHistory           pawnHistory;
-    CorrectionHistory     correctionHistory;
+
+    CorrectionHistory<Pawn>         pawnCorrectionHistory;
+    CorrectionHistory<Minor>        minorPieceCorrectionHistory;
+    CorrectionHistory<NonPawn>      nonPawnCorrectionHistory;
+    CorrectionHistory<Continuation> continuationCorrectionHistory;
 
    private:
     void iterative_deepening();
 
+    void do_move(Position& pos, const Move move, StateInfo& st);
+    void do_move(Position& pos, const Move move, StateInfo& st, const bool givesCheck);
+    void do_null_move(Position& pos, StateInfo& st);
+    void undo_move(Position& pos, const Move move);
+    void undo_null_move(Position& pos);
+
     // This is the main search function, for both PV and non-PV nodes
     template<NodeType nodeType>
     Value search(Position& pos, Stack* ss, Value alpha, Value beta, Depth depth, bool cutNode);
@@ -305,6 +320,8 @@ class Worker {
     TimePoint elapsed() const;
     TimePoint elapsed_time() const;
 
+    Value evaluate(const Position&);
+
     LimitsType limits;
 
     size_t                pvIdx, pvLast;
@@ -336,12 +353,18 @@ class Worker {
     const LazyNumaReplicated<Eval::NNUE::Networks>& networks;
 
     // Used by NNUE
+    Eval::NNUE::AccumulatorStack  accumulatorStack;
     Eval::NNUE::AccumulatorCaches refreshTable;
 
     friend class Stockfish::ThreadPool;
     friend class SearchManager;
 };
 
+struct ConthistBonus {
+    int index;
+    int weight;
+};
+
 
 }  // namespace Search
 

src/syzygy/tbprobe.cpp

@@ -1,6 +1,6 @@
 /*
   Stockfish, a UCI chess playing engine derived from Glaurung 2.1
-  Copyright (C) 2004-2024 The Stockfish developers (see AUTHORS file)
+  Copyright (C) 2004-2025 The Stockfish developers (see AUTHORS file)
 
   Stockfish is free software: you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
@@ -1620,7 +1620,7 @@ bool Tablebases::root_probe(Position&          pos,
             WDLScore wdl = -probe_wdl(pos, &result);
             dtz          = dtz_before_zeroing(wdl);
         }
-        else if (pos.is_draw(1))
+        else if ((rule50 && pos.is_draw(1)) || pos.is_repetition(1))
         {
             // In case a root move leads to a draw by repetition or 50-move rule,
             // we set dtz to zero. Note: since we are only 1 ply from the root,

src/syzygy/tbprobe.h

@@ -1,6 +1,6 @@
 /*
   Stockfish, a UCI chess playing engine derived from Glaurung 2.1
-  Copyright (C) 2004-2024 The Stockfish developers (see AUTHORS file)
+  Copyright (C) 2004-2025 The Stockfish developers (see AUTHORS file)
 
   Stockfish is free software: you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by

src/thread.cpp

@@ -1,6 +1,6 @@
 /*
   Stockfish, a UCI chess playing engine derived from Glaurung 2.1
-  Copyright (C) 2004-2024 The Stockfish developers (see AUTHORS file)
+  Copyright (C) 2004-2025 The Stockfish developers (see AUTHORS file)
 
   Stockfish is free software: you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
@@ -329,13 +329,13 @@ Thread* ThreadPool::get_best_thread() const {
         const auto bestThreadMoveVote = votes[bestThreadPV[0]];
         const auto newThreadMoveVote  = votes[newThreadPV[0]];
 
-        const bool bestThreadInProvenWin = bestThreadScore >= VALUE_TB_WIN_IN_MAX_PLY;
-        const bool newThreadInProvenWin  = newThreadScore >= VALUE_TB_WIN_IN_MAX_PLY;
+        const bool bestThreadInProvenWin = is_win(bestThreadScore);
+        const bool newThreadInProvenWin  = is_win(newThreadScore);
 
         const bool bestThreadInProvenLoss =
-          bestThreadScore != -VALUE_INFINITE && bestThreadScore <= VALUE_TB_LOSS_IN_MAX_PLY;
+          bestThreadScore != -VALUE_INFINITE && is_loss(bestThreadScore);
         const bool newThreadInProvenLoss =
-          newThreadScore != -VALUE_INFINITE && newThreadScore <= VALUE_TB_LOSS_IN_MAX_PLY;
+          newThreadScore != -VALUE_INFINITE && is_loss(newThreadScore);
 
         // We make sure not to pick a thread with truncated principal variation
         const bool betterVotingValue =
@@ -355,7 +355,7 @@ Thread* ThreadPool::get_best_thread() const {
                 bestThread = th.get();
         }
         else if (newThreadInProvenWin || newThreadInProvenLoss
-                 || (newThreadScore > VALUE_TB_LOSS_IN_MAX_PLY
+                 || (!is_loss(newThreadScore)
                      && (newThreadMoveVote > bestThreadMoveVote
                          || (newThreadMoveVote == bestThreadMoveVote && betterVotingValue))))
             bestThread = th.get();

src/thread.h

@@ -1,6 +1,6 @@
 /*
   Stockfish, a UCI chess playing engine derived from Glaurung 2.1
-  Copyright (C) 2004-2024 The Stockfish developers (see AUTHORS file)
+  Copyright (C) 2004-2025 The Stockfish developers (see AUTHORS file)
 
   Stockfish is free software: you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by

src/thread_win32_osx.h

@@ -1,6 +1,6 @@
 /*
   Stockfish, a UCI chess playing engine derived from Glaurung 2.1
-  Copyright (C) 2004-2024 The Stockfish developers (see AUTHORS file)
+  Copyright (C) 2004-2025 The Stockfish developers (see AUTHORS file)
 
   Stockfish is free software: you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by

src/timeman.cpp

@@ -1,6 +1,6 @@
 /*
   Stockfish, a UCI chess playing engine derived from Glaurung 2.1
-  Copyright (C) 2004-2024 The Stockfish developers (see AUTHORS file)
+  Copyright (C) 2004-2025 The Stockfish developers (see AUTHORS file)
 
   Stockfish is free software: you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
@@ -87,18 +87,20 @@ void TimeManagement::init(Search::LimitsType& limits,
     const TimePoint scaledTime  = limits.time[us] / scaleFactor;
     const TimePoint scaledInc   = limits.inc[us] / scaleFactor;
 
-    // Maximum move horizon of 50 moves
-    int mtg = limits.movestogo ? std::min(limits.movestogo, 50) : 50;
+    // Maximum move horizon
+    int centiMTG = limits.movestogo ? std::min(limits.movestogo * 100, 5000) : 5051;
 
     // If less than one second, gradually reduce mtg
-    if (scaledTime < 1000 && double(mtg) / scaledInc > 0.05)
+    if (scaledTime < 1000 && double(centiMTG) / scaledInc > 5.051)
     {
-        mtg = scaledTime * 0.05;
+        centiMTG = scaledTime * 5.051;
     }
 
     // Make sure timeLeft is > 0 since we may use it as a divisor
-    TimePoint timeLeft = std::max(TimePoint(1), limits.time[us] + limits.inc[us] * (mtg - 1)
-                                                  - moveOverhead * (2 + mtg));
+    TimePoint timeLeft =
+      std::max(TimePoint(1),
+               limits.time[us]
+                 + (limits.inc[us] * (centiMTG - 100) - moveOverhead * (200 + centiMTG)) / 100);
 
     // x basetime (+ z increment)
     // If there is a healthy increment, timeLeft can exceed the actual available
@@ -107,31 +109,32 @@ void TimeManagement::init(Search::LimitsType& limits,
     {
         // Extra time according to timeLeft
         if (originalTimeAdjust < 0)
-            originalTimeAdjust = 0.3285 * std::log10(timeLeft) - 0.4830;
+            originalTimeAdjust = 0.3128 * std::log10(timeLeft) - 0.4354;
 
         // Calculate time constants based on current time left.
         double logTimeInSec = std::log10(scaledTime / 1000.0);
-        double optConstant  = std::min(0.00308 + 0.000319 * logTimeInSec, 0.00506);
-        double maxConstant  = std::max(3.39 + 3.01 * logTimeInSec, 2.93);
+        double optConstant  = std::min(0.0032116 + 0.000321123 * logTimeInSec, 0.00508017);
+        double maxConstant  = std::max(3.3977 + 3.03950 * logTimeInSec, 2.94761);
 
-        optScale = std::min(0.0122 + std::pow(ply + 2.95, 0.462) * optConstant,
-                            0.213 * limits.time[us] / timeLeft)
+        optScale = std::min(0.0121431 + std::pow(ply + 2.94693, 0.461073) * optConstant,
+                            0.213035 * limits.time[us] / timeLeft)
                  * originalTimeAdjust;
 
-        maxScale = std::min(6.64, maxConstant + ply / 12.0);
+        maxScale = std::min(6.67704, maxConstant + ply / 11.9847);
     }
 
     // x moves in y seconds (+ z increment)
     else
     {
-        optScale = std::min((0.88 + ply / 116.4) / mtg, 0.88 * limits.time[us] / timeLeft);
-        maxScale = std::min(6.3, 1.5 + 0.11 * mtg);
+        optScale =
+          std::min((0.88 + ply / 116.4) / (centiMTG / 100.0), 0.88 * limits.time[us] / timeLeft);
+        maxScale = 1.3 + 0.11 * (centiMTG / 100.0);
     }
 
     // Limit the maximum possible time for this move
     optimumTime = TimePoint(optScale * timeLeft);
     maximumTime =
-      TimePoint(std::min(0.825 * limits.time[us] - moveOverhead, maxScale * optimumTime)) - 10;
+      TimePoint(std::min(0.825179 * limits.time[us] - moveOverhead, maxScale * optimumTime)) - 10;
 
     if (options["Ponder"])
         optimumTime += optimumTime / 4;

src/timeman.h

@@ -1,6 +1,6 @@
 /*
   Stockfish, a UCI chess playing engine derived from Glaurung 2.1
-  Copyright (C) 2004-2024 The Stockfish developers (see AUTHORS file)
+  Copyright (C) 2004-2025 The Stockfish developers (see AUTHORS file)
 
   Stockfish is free software: you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by

src/tt.cpp

@@ -1,6 +1,6 @@
 /*
   Stockfish, a UCI chess playing engine derived from Glaurung 2.1
-  Copyright (C) 2004-2024 The Stockfish developers (see AUTHORS file)
+  Copyright (C) 2004-2025 The Stockfish developers (see AUTHORS file)
 
   Stockfish is free software: you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
@@ -193,13 +193,13 @@ void TranspositionTable::clear(ThreadPool& threads) {
 // Returns an approximation of the hashtable
 // occupation during a search. The hash is x permill full, as per UCI protocol.
 // Only counts entries which match the current generation.
-int TranspositionTable::hashfull() const {
-
-    int cnt = 0;
+int TranspositionTable::hashfull(int maxAge) const {
+    int maxAgeInternal = maxAge << GENERATION_BITS;
+    int cnt            = 0;
     for (int i = 0; i < 1000; ++i)
         for (int j = 0; j < ClusterSize; ++j)
             cnt += table[i].entry[j].is_occupied()
-                && (table[i].entry[j].genBound8 & GENERATION_MASK) == generation8;
+                && table[i].entry[j].relative_age(generation8) <= maxAgeInternal;
 
     return cnt / ClusterSize;
 }
@@ -238,7 +238,9 @@ std::tuple<bool, TTData, TTWriter> TranspositionTable::probe(const Key key) cons
             > tte[i].depth8 - tte[i].relative_age(generation8) * 2)
             replace = &tte[i];
 
-    return {false, TTData(), TTWriter(replace)};
+    return {false,
+            TTData{Move::none(), VALUE_NONE, VALUE_NONE, DEPTH_ENTRY_OFFSET, BOUND_NONE, false},
+            TTWriter(replace)};
 }
 
 

src/tt.h

@@ -1,6 +1,6 @@
 /*
   Stockfish, a UCI chess playing engine derived from Glaurung 2.1
-  Copyright (C) 2004-2024 The Stockfish developers (see AUTHORS file)
+  Copyright (C) 2004-2025 The Stockfish developers (see AUTHORS file)
 
   Stockfish is free software: you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
@@ -51,6 +51,18 @@ struct TTData {
     Depth depth;
     Bound bound;
     bool  is_pv;
+
+    TTData() = delete;
+
+    // clang-format off
+    TTData(Move m, Value v, Value ev, Depth d, Bound b, bool pv) :
+        move(m),
+        value(v),
+        eval(ev),
+        depth(d),
+        bound(b),
+        is_pv(pv) {};
+    // clang-format on
 };
 
 
@@ -73,7 +85,7 @@ class TranspositionTable {
 
     void resize(size_t mbSize, ThreadPool& threads);  // Set TT size
     void clear(ThreadPool& threads);                  // Re-initialize memory, multithreaded
-    int  hashfull()
+    int  hashfull(int maxAge = 0)
       const;  // Approximate what fraction of entries (permille) have been written to during this root search
 
     void

src/tune.cpp

@@ -1,6 +1,6 @@
 /*
   Stockfish, a UCI chess playing engine derived from Glaurung 2.1
-  Copyright (C) 2004-2024 The Stockfish developers (see AUTHORS file)
+  Copyright (C) 2004-2025 The Stockfish developers (see AUTHORS file)
 
   Stockfish is free software: you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
@@ -55,7 +55,7 @@ void Tune::make_option(OptionsMap* opts, const string& n, int v, const SetRange&
     if (TuneResults.count(n))
         v = TuneResults[n];
 
-    (*opts)[n] << Option(v, r(v).first, r(v).second, on_tune);
+    opts->add(n, Option(v, r(v).first, r(v).second, on_tune));
     LastOption = &((*opts)[n]);
 
     // Print formatted parameters, ready to be copy-pasted in Fishtest

src/tune.h

@@ -1,6 +1,6 @@
 /*
   Stockfish, a UCI chess playing engine derived from Glaurung 2.1
-  Copyright (C) 2004-2024 The Stockfish developers (see AUTHORS file)
+  Copyright (C) 2004-2025 The Stockfish developers (see AUTHORS file)
 
   Stockfish is free software: you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by

src/types.h

@@ -1,6 +1,6 @@
 /*
   Stockfish, a UCI chess playing engine derived from Glaurung 2.1
-  Copyright (C) 2004-2024 The Stockfish developers (see AUTHORS file)
+  Copyright (C) 2004-2025 The Stockfish developers (see AUTHORS file)
 
   Stockfish is free software: you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
@@ -155,6 +155,21 @@ constexpr Value VALUE_TB                 = VALUE_MATE_IN_MAX_PLY - 1;
 constexpr Value VALUE_TB_WIN_IN_MAX_PLY  = VALUE_TB - MAX_PLY;
 constexpr Value VALUE_TB_LOSS_IN_MAX_PLY = -VALUE_TB_WIN_IN_MAX_PLY;
 
+
+constexpr bool is_valid(Value value) { return value != VALUE_NONE; }
+
+constexpr bool is_win(Value value) {
+    assert(is_valid(value));
+    return value >= VALUE_TB_WIN_IN_MAX_PLY;
+}
+
+constexpr bool is_loss(Value value) {
+    assert(is_valid(value));
+    return value <= VALUE_TB_LOSS_IN_MAX_PLY;
+}
+
+constexpr bool is_decisive(Value value) { return is_win(value) || is_loss(value); }
+
 // In the code, we make the assumption that these values
 // are such that non_pawn_material() can be used to uniquely
 // identify the material on the board.

src/uci.cpp

@@ -1,6 +1,6 @@
 /*
   Stockfish, a UCI chess playing engine derived from Glaurung 2.1
-  Copyright (C) 2004-2024 The Stockfish developers (see AUTHORS file)
+  Copyright (C) 2004-2025 The Stockfish developers (see AUTHORS file)
 
   Stockfish is free software: you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
@@ -22,6 +22,7 @@
 #include <cctype>
 #include <cmath>
 #include <cstdint>
+#include <iterator>
 #include <optional>
 #include <sstream>
 #include <string_view>
@@ -30,6 +31,7 @@
 
 #include "benchmark.h"
 #include "engine.h"
+#include "memory.h"
 #include "movegen.h"
 #include "position.h"
 #include "score.h"
@@ -39,6 +41,8 @@
 
 namespace Stockfish {
 
+constexpr auto BenchmarkCommand = "speedtest";
+
 constexpr auto StartFEN = "rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR w KQkq - 0 1";
 template<typename... Ts>
 struct overload: Ts... {
@@ -48,7 +52,7 @@ struct overload: Ts... {
 template<typename... Ts>
 overload(Ts...) -> overload<Ts...>;
 
-void UCIEngine::print_info_string(const std::string& str) {
+void UCIEngine::print_info_string(std::string_view str) {
     sync_cout_start();
     for (auto& line : split(str, "\n"))
     {
@@ -69,11 +73,16 @@ UCIEngine::UCIEngine(int argc, char** argv) :
             print_info_string(*str);
     });
 
+    init_search_update_listeners();
+}
+
+void UCIEngine::init_search_update_listeners() {
     engine.set_on_iter([](const auto& i) { on_iter(i); });
     engine.set_on_update_no_moves([](const auto& i) { on_update_no_moves(i); });
     engine.set_on_update_full(
       [this](const auto& i) { on_update_full(i, engine.get_options()["UCI_ShowWDL"]); });
     engine.set_on_bestmove([](const auto& bm, const auto& p) { on_bestmove(bm, p); });
+    engine.set_on_verify_networks([](const auto& s) { print_info_string(s); });
 }
 
 void UCIEngine::loop() {
@@ -117,7 +126,7 @@ void UCIEngine::loop() {
         {
             // send info strings after the go command is sent for old GUIs and python-chess
             print_info_string(engine.numa_config_information_as_string());
-            print_info_string(engine.thread_binding_information_as_string());
+            print_info_string(engine.thread_allocation_information_as_string());
             go(is);
         }
         else if (token == "position")
@@ -133,6 +142,8 @@ void UCIEngine::loop() {
             engine.flip();
         else if (token == "bench")
             bench(is);
+        else if (token == BenchmarkCommand)
+            benchmark(is);
         else if (token == "d")
             sync_cout << engine.visualize() << sync_endl;
         else if (token == "eval")
@@ -285,6 +296,169 @@ void UCIEngine::bench(std::istream& args) {
     engine.set_on_update_full([&](const auto& i) { on_update_full(i, options["UCI_ShowWDL"]); });
 }
 
+void UCIEngine::benchmark(std::istream& args) {
+    // Probably not very important for a test this long, but include for completeness and sanity.
+    static constexpr int NUM_WARMUP_POSITIONS = 3;
+
+    std::string token;
+    uint64_t    nodes = 0, cnt = 1;
+    uint64_t    nodesSearched = 0;
+
+    engine.set_on_update_full([&](const Engine::InfoFull& i) { nodesSearched = i.nodes; });
+
+    engine.set_on_iter([](const auto&) {});
+    engine.set_on_update_no_moves([](const auto&) {});
+    engine.set_on_bestmove([](const auto&, const auto&) {});
+    engine.set_on_verify_networks([](const auto&) {});
+
+    Benchmark::BenchmarkSetup setup = Benchmark::setup_benchmark(args);
+
+    const int numGoCommands = count_if(setup.commands.begin(), setup.commands.end(),
+                                       [](const std::string& s) { return s.find("go ") == 0; });
+
+    TimePoint totalTime = 0;
+
+    // Set options once at the start.
+    auto ss = std::istringstream("name Threads value " + std::to_string(setup.threads));
+    setoption(ss);
+    ss = std::istringstream("name Hash value " + std::to_string(setup.ttSize));
+    setoption(ss);
+    ss = std::istringstream("name UCI_Chess960 value false");
+    setoption(ss);
+
+    // Warmup
+    for (const auto& cmd : setup.commands)
+    {
+        std::istringstream is(cmd);
+        is >> std::skipws >> token;
+
+        if (token == "go")
+        {
+            // One new line is produced by the search, so omit it here
+            std::cerr << "\rWarmup position " << cnt++ << '/' << NUM_WARMUP_POSITIONS;
+
+            Search::LimitsType limits = parse_limits(is);
+
+            TimePoint elapsed = now();
+
+            // Run with silenced network verification
+            engine.go(limits);
+            engine.wait_for_search_finished();
+
+            totalTime += now() - elapsed;
+
+            nodes += nodesSearched;
+            nodesSearched = 0;
+        }
+        else if (token == "position")
+            position(is);
+        else if (token == "ucinewgame")
+        {
+            engine.search_clear();  // search_clear may take a while
+        }
+
+        if (cnt > NUM_WARMUP_POSITIONS)
+            break;
+    }
+
+    std::cerr << "\n";
+
+    cnt   = 1;
+    nodes = 0;
+
+    int           numHashfullReadings = 0;
+    constexpr int hashfullAges[]      = {0, 999};  // Only normal hashfull and touched hash.
+    int           totalHashfull[std::size(hashfullAges)] = {0};
+    int           maxHashfull[std::size(hashfullAges)]   = {0};
+
+    auto updateHashfullReadings = [&]() {
+        numHashfullReadings += 1;
+
+        for (int i = 0; i < static_cast<int>(std::size(hashfullAges)); ++i)
+        {
+            const int hashfull = engine.get_hashfull(hashfullAges[i]);
+            maxHashfull[i]     = std::max(maxHashfull[i], hashfull);
+            totalHashfull[i] += hashfull;
+        }
+    };
+
+    engine.search_clear();  // search_clear may take a while
+
+    for (const auto& cmd : setup.commands)
+    {
+        std::istringstream is(cmd);
+        is >> std::skipws >> token;
+
+        if (token == "go")
+        {
+            // One new line is produced by the search, so omit it here
+            std::cerr << "\rPosition " << cnt++ << '/' << numGoCommands;
+
+            Search::LimitsType limits = parse_limits(is);
+
+            TimePoint elapsed = now();
+
+            // Run with silenced network verification
+            engine.go(limits);
+            engine.wait_for_search_finished();
+
+            totalTime += now() - elapsed;
+
+            updateHashfullReadings();
+
+            nodes += nodesSearched;
+            nodesSearched = 0;
+        }
+        else if (token == "position")
+            position(is);
+        else if (token == "ucinewgame")
+        {
+            engine.search_clear();  // search_clear may take a while
+        }
+    }
+
+    totalTime = std::max<TimePoint>(totalTime, 1);  // Ensure positivity to avoid a 'divide by zero'
+
+    dbg_print();
+
+    std::cerr << "\n";
+
+    static_assert(
+      std::size(hashfullAges) == 2 && hashfullAges[0] == 0 && hashfullAges[1] == 999,
+      "Hardcoded for display. Would complicate the code needlessly in the current state.");
+
+    std::string threadBinding = engine.thread_binding_information_as_string();
+    if (threadBinding.empty())
+        threadBinding = "none";
+
+    // clang-format off
+
+    std::cerr << "==========================="
+              << "\nVersion                    : "
+              << engine_version_info()
+              // "\nCompiled by                : "
+              << compiler_info()
+              << "Large pages                : " << (has_large_pages() ? "yes" : "no")
+              << "\nUser invocation            : " << BenchmarkCommand << " "
+              << setup.originalInvocation << "\nFilled invocation          : " << BenchmarkCommand
+              << " " << setup.filledInvocation
+              << "\nAvailable processors       : " << engine.get_numa_config_as_string()
+              << "\nThread count               : " << setup.threads
+              << "\nThread binding             : " << threadBinding
+              << "\nTT size [MiB]              : " << setup.ttSize
+              << "\nHash max, avg [per mille]  : "
+              << "\n    single search          : " << maxHashfull[0] << ", "
+              << totalHashfull[0] / numHashfullReadings
+              << "\n    single game            : " << maxHashfull[1] << ", "
+              << totalHashfull[1] / numHashfullReadings
+              << "\nTotal nodes searched       : " << nodes
+              << "\nTotal search time [s]      : " << totalTime / 1000.0
+              << "\nNodes/second               : " << 1000 * nodes / totalTime << std::endl;
+
+    // clang-format on
+
+    init_search_update_listeners();
+}
 
 void UCIEngine::setoption(std::istringstream& is) {
     engine.wait_for_search_finished();
@@ -339,8 +513,8 @@ WinRateParams win_rate_params(const Position& pos) {
     double m = std::clamp(material, 17, 78) / 58.0;
 
     // Return a = p_a(material) and b = p_b(material), see github.com/official-stockfish/WDL_model
-    constexpr double as[] = {-37.45051876, 121.19101539, -132.78783573, 420.70576692};
-    constexpr double bs[] = {90.26261072, -137.26549898, 71.10130540, 51.35259597};
+    constexpr double as[] = {-13.50030198, 40.92780883, -36.82753545, 386.83004070};
+    constexpr double bs[] = {96.53354896, -165.79058388, 90.89679019, 49.29561889};
 
     double a = (((as[0] * m + as[1]) * m + as[2]) * m) + as[3];
     double b = (((bs[0] * m + bs[1]) * m + bs[2]) * m) + bs[3];

src/uci.h

@@ -1,6 +1,6 @@
 /*
   Stockfish, a UCI chess playing engine derived from Glaurung 2.1
-  Copyright (C) 2004-2024 The Stockfish developers (see AUTHORS file)
+  Copyright (C) 2004-2025 The Stockfish developers (see AUTHORS file)
 
   Stockfish is free software: you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
@@ -58,10 +58,11 @@ class UCIEngine {
     Engine      engine;
     CommandLine cli;
 
-    static void print_info_string(const std::string& str);
+    static void print_info_string(std::string_view str);
 
     void          go(std::istringstream& is);
     void          bench(std::istream& args);
+    void          benchmark(std::istream& args);
     void          position(std::istringstream& is);
     void          setoption(std::istringstream& is);
     std::uint64_t perft(const Search::LimitsType&);
@@ -70,6 +71,8 @@ class UCIEngine {
     static void on_update_full(const Engine::InfoFull& info, bool showWDL);
     static void on_iter(const Engine::InfoIter& info);
     static void on_bestmove(std::string_view bestmove, std::string_view ponder);
+
+    void init_search_update_listeners();
 };
 
 }  // namespace Stockfish

src/ucioption.cpp

@@ -1,6 +1,6 @@
 /*
   Stockfish, a UCI chess playing engine derived from Glaurung 2.1
-  Copyright (C) 2004-2024 The Stockfish developers (see AUTHORS file)
+  Copyright (C) 2004-2025 The Stockfish developers (see AUTHORS file)
 
   Stockfish is free software: you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
@@ -21,6 +21,7 @@
 #include <algorithm>
 #include <cassert>
 #include <cctype>
+#include <cstdlib>
 #include <iostream>
 #include <sstream>
 #include <utility>
@@ -57,17 +58,31 @@ void OptionsMap::setoption(std::istringstream& is) {
         sync_cout << "No such option: " << name << sync_endl;
 }
 
-Option OptionsMap::operator[](const std::string& name) const {
+const Option& OptionsMap::operator[](const std::string& name) const {
     auto it = options_map.find(name);
-    return it != options_map.end() ? it->second : Option(this);
+    assert(it != options_map.end());
+    return it->second;
 }
 
-Option& OptionsMap::operator[](const std::string& name) {
+// Inits options and assigns idx in the correct printing order
+void OptionsMap::add(const std::string& name, const Option& option) {
     if (!options_map.count(name))
-        options_map[name] = Option(this);
-    return options_map[name];
+    {
+        static size_t insert_order = 0;
+
+        options_map[name] = option;
+
+        options_map[name].parent = this;
+        options_map[name].idx    = insert_order++;
+    }
+    else
+    {
+        std::cerr << "Option \"" << name << "\" was already added!" << std::endl;
+        std::exit(EXIT_FAILURE);
+    }
 }
 
+
 std::size_t OptionsMap::count(const std::string& name) const { return options_map.count(name); }
 
 Option::Option(const OptionsMap* map) :
@@ -130,19 +145,6 @@ bool Option::operator==(const char* s) const {
 bool Option::operator!=(const char* s) const { return !(*this == s); }
 
 
-// Inits options and assigns idx in the correct printing order
-
-void Option::operator<<(const Option& o) {
-
-    static size_t insert_order = 0;
-
-    auto p = this->parent;
-    *this  = o;
-
-    this->parent = p;
-    idx          = insert_order++;
-}
-
 // Updates currentValue and triggers on_change() action. It's up to
 // the GUI to check for option's limits, but we could receive the new value
 // from the user by console window, so let's check the bounds anyway.
@@ -161,7 +163,7 @@ Option& Option::operator=(const std::string& v) {
         std::string        token;
         std::istringstream ss(defaultValue);
         while (ss >> token)
-            comboMap[token] << Option();
+            comboMap.add(token, Option());
         if (!comboMap.count(v) || v == "var")
             return *this;
     }

src/ucioption.h

@@ -1,6 +1,6 @@
 /*
   Stockfish, a UCI chess playing engine derived from Glaurung 2.1
-  Copyright (C) 2004-2024 The Stockfish developers (see AUTHORS file)
+  Copyright (C) 2004-2025 The Stockfish developers (see AUTHORS file)
 
   Stockfish is free software: you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
@@ -54,12 +54,13 @@ class Option {
 
     friend std::ostream& operator<<(std::ostream&, const OptionsMap&);
 
+    int operator<<(const Option&) = delete;
+
    private:
     friend class OptionsMap;
     friend class Engine;
     friend class Tune;
 
-    void operator<<(const Option&);
 
     std::string       defaultValue, currentValue, type;
     int               min, max;
@@ -82,8 +83,9 @@ class OptionsMap {
 
     void setoption(std::istringstream&);
 
-    Option  operator[](const std::string&) const;
-    Option& operator[](const std::string&);
+    const Option& operator[](const std::string&) const;
+
+    void add(const std::string&, const Option& option);
 
     std::size_t count(const std::string&) const;
 

tests/.gitattributes

@@ -0,0 +1 @@
+*.sh text eol=lf

tests/instrumented.py

@@ -0,0 +1,520 @@
+import argparse
+import re
+import sys
+import subprocess
+import pathlib
+import os
+
+from testing import (
+    EPD,
+    TSAN,
+    Stockfish as Engine,
+    MiniTestFramework,
+    OrderedClassMembers,
+    Valgrind,
+    Syzygy,
+)
+
+PATH = pathlib.Path(__file__).parent.resolve()
+CWD = os.getcwd()
+
+
+def get_prefix():
+    if args.valgrind:
+        return Valgrind.get_valgrind_command()
+    if args.valgrind_thread:
+        return Valgrind.get_valgrind_thread_command()
+
+    return []
+
+
+def get_threads():
+    if args.valgrind_thread or args.sanitizer_thread:
+        return 2
+    return 1
+
+
+def get_path():
+    return os.path.abspath(os.path.join(CWD, args.stockfish_path))
+
+
+def postfix_check(output):
+    if args.sanitizer_undefined:
+        for idx, line in enumerate(output):
+            if "runtime error:" in line:
+                # print next possible 50 lines
+                for i in range(50):
+                    debug_idx = idx + i
+                    if debug_idx < len(output):
+                        print(output[debug_idx])
+                return False
+
+    if args.sanitizer_thread:
+        for idx, line in enumerate(output):
+            if "WARNING: ThreadSanitizer:" in line:
+                # print next possible 50 lines
+                for i in range(50):
+                    debug_idx = idx + i
+                    if debug_idx < len(output):
+                        print(output[debug_idx])
+                return False
+
+    return True
+
+
+def Stockfish(*args, **kwargs):
+    return Engine(get_prefix(), get_path(), *args, **kwargs)
+
+
+class TestCLI(metaclass=OrderedClassMembers):
+
+    def beforeAll(self):
+        pass
+
+    def afterAll(self):
+        pass
+
+    def beforeEach(self):
+        self.stockfish = None
+
+    def afterEach(self):
+        assert postfix_check(self.stockfish.get_output()) == True
+        self.stockfish.clear_output()
+
+    def test_eval(self):
+        self.stockfish = Stockfish("eval".split(" "), True)
+        assert self.stockfish.process.returncode == 0
+
+    def test_go_nodes_1000(self):
+        self.stockfish = Stockfish("go nodes 1000".split(" "), True)
+        assert self.stockfish.process.returncode == 0
+
+    def test_go_depth_10(self):
+        self.stockfish = Stockfish("go depth 10".split(" "), True)
+        assert self.stockfish.process.returncode == 0
+
+    def test_go_perft_4(self):
+        self.stockfish = Stockfish("go perft 4".split(" "), True)
+        assert self.stockfish.process.returncode == 0
+
+    def test_go_movetime_1000(self):
+        self.stockfish = Stockfish("go movetime 1000".split(" "), True)
+        assert self.stockfish.process.returncode == 0
+
+    def test_go_wtime_8000_btime_8000_winc_500_binc_500(self):
+        self.stockfish = Stockfish(
+            "go wtime 8000 btime 8000 winc 500 binc 500".split(" "),
+            True,
+        )
+        assert self.stockfish.process.returncode == 0
+
+    def test_go_wtime_1000_btime_1000_winc_0_binc_0(self):
+        self.stockfish = Stockfish(
+            "go wtime 1000 btime 1000 winc 0 binc 0".split(" "),
+            True,
+        )
+        assert self.stockfish.process.returncode == 0
+
+    def test_go_wtime_1000_btime_1000_winc_0_binc_0_movestogo_5(self):
+        self.stockfish = Stockfish(
+            "go wtime 1000 btime 1000 winc 0 binc 0 movestogo 5".split(" "),
+            True,
+        )
+        assert self.stockfish.process.returncode == 0
+
+    def test_go_movetime_200(self):
+        self.stockfish = Stockfish("go movetime 200".split(" "), True)
+        assert self.stockfish.process.returncode == 0
+
+    def test_go_nodes_20000_searchmoves_e2e4_d2d4(self):
+        self.stockfish = Stockfish(
+            "go nodes 20000 searchmoves e2e4 d2d4".split(" "), True
+        )
+        assert self.stockfish.process.returncode == 0
+
+    def test_bench_128_threads_8_default_depth(self):
+        self.stockfish = Stockfish(
+            f"bench 128 {get_threads()} 8 default depth".split(" "),
+            True,
+        )
+        assert self.stockfish.process.returncode == 0
+
+    def test_bench_128_threads_3_bench_tmp_epd_depth(self):
+        self.stockfish = Stockfish(
+            f"bench 128 {get_threads()} 3 {os.path.join(PATH,'bench_tmp.epd')} depth".split(
+                " "
+            ),
+            True,
+        )
+        assert self.stockfish.process.returncode == 0
+
+    def test_d(self):
+        self.stockfish = Stockfish("d".split(" "), True)
+        assert self.stockfish.process.returncode == 0
+
+    def test_compiler(self):
+        self.stockfish = Stockfish("compiler".split(" "), True)
+        assert self.stockfish.process.returncode == 0
+
+    def test_license(self):
+        self.stockfish = Stockfish("license".split(" "), True)
+        assert self.stockfish.process.returncode == 0
+
+    def test_uci(self):
+        self.stockfish = Stockfish("uci".split(" "), True)
+        assert self.stockfish.process.returncode == 0
+
+    def test_export_net_verify_nnue(self):
+        current_path = os.path.abspath(os.getcwd())
+        self.stockfish = Stockfish(
+            f"export_net {os.path.join(current_path , 'verify.nnue')}".split(" "), True
+        )
+        assert self.stockfish.process.returncode == 0
+
+    # verify the generated net equals the base net
+
+    def test_network_equals_base(self):
+        self.stockfish = Stockfish(
+            ["uci"],
+            True,
+        )
+
+        output = self.stockfish.process.stdout
+
+        # find line
+        for line in output.split("\n"):
+            if "option name EvalFile type string default" in line:
+                network = line.split(" ")[-1]
+                break
+
+        # find network file in src dir
+        network = os.path.join(PATH.parent.resolve(), "src", network)
+
+        if not os.path.exists(network):
+            print(
+                f"Network file {network} not found, please download the network file over the make command."
+            )
+            assert False
+
+        diff = subprocess.run(["diff", network, f"verify.nnue"])
+
+        assert diff.returncode == 0
+
+
+class TestInteractive(metaclass=OrderedClassMembers):
+    def beforeAll(self):
+        self.stockfish = Stockfish()
+
+    def afterAll(self):
+        self.stockfish.quit()
+        assert self.stockfish.close() == 0
+
+    def afterEach(self):
+        assert postfix_check(self.stockfish.get_output()) == True
+        self.stockfish.clear_output()
+
+    def test_startup_output(self):
+        self.stockfish.starts_with("Stockfish")
+
+    def test_uci_command(self):
+        self.stockfish.send_command("uci")
+        self.stockfish.equals("uciok")
+
+    def test_set_threads_option(self):
+        self.stockfish.send_command(f"setoption name Threads value {get_threads()}")
+
+    def test_ucinewgame_and_startpos_nodes_1000(self):
+        self.stockfish.send_command("ucinewgame")
+        self.stockfish.send_command("position startpos")
+        self.stockfish.send_command("go nodes 1000")
+        self.stockfish.starts_with("bestmove")
+
+    def test_ucinewgame_and_startpos_moves(self):
+        self.stockfish.send_command("ucinewgame")
+        self.stockfish.send_command("position startpos moves e2e4 e7e6")
+        self.stockfish.send_command("go nodes 1000")
+        self.stockfish.starts_with("bestmove")
+
+    def test_fen_position_1(self):
+        self.stockfish.send_command("ucinewgame")
+        self.stockfish.send_command("position fen 5rk1/1K4p1/8/8/3B4/8/8/8 b - - 0 1")
+        self.stockfish.send_command("go nodes 1000")
+        self.stockfish.starts_with("bestmove")
+
+    def test_fen_position_2_flip(self):
+        self.stockfish.send_command("ucinewgame")
+        self.stockfish.send_command("position fen 5rk1/1K4p1/8/8/3B4/8/8/8 b - - 0 1")
+        self.stockfish.send_command("flip")
+        self.stockfish.send_command("go nodes 1000")
+        self.stockfish.starts_with("bestmove")
+
+    def test_depth_5_with_callback(self):
+        self.stockfish.send_command("ucinewgame")
+        self.stockfish.send_command("position startpos")
+        self.stockfish.send_command("go depth 5")
+
+        def callback(output):
+            regex = r"info depth \d+ seldepth \d+ multipv \d+ score cp \d+ nodes \d+ nps \d+ hashfull \d+ tbhits \d+ time \d+ pv"
+            if output.startswith("info depth") and not re.match(regex, output):
+                assert False
+            if output.startswith("bestmove"):
+                return True
+            return False
+
+        self.stockfish.check_output(callback)
+
+    def test_ucinewgame_and_go_depth_9(self):
+        self.stockfish.send_command("ucinewgame")
+        self.stockfish.send_command("setoption name UCI_ShowWDL value true")
+        self.stockfish.send_command("position startpos")
+        self.stockfish.send_command("go depth 9")
+
+        depth = 1
+
+        def callback(output):
+            nonlocal depth
+
+            regex = rf"info depth {depth} seldepth \d+ multipv \d+ score cp \d+ wdl \d+ \d+ \d+ nodes \d+ nps \d+ hashfull \d+ tbhits \d+ time \d+ pv"
+
+            if output.startswith("info depth"):
+                if not re.match(regex, output):
+                    assert False
+                depth += 1
+
+            if output.startswith("bestmove"):
+                assert depth == 10
+                return True
+
+            return False
+
+        self.stockfish.check_output(callback)
+
+    def test_clear_hash(self):
+        self.stockfish.send_command("setoption name Clear Hash")
+
+    def test_fen_position_mate_1(self):
+        self.stockfish.send_command("ucinewgame")
+        self.stockfish.send_command(
+            "position fen 5K2/8/2qk4/2nPp3/3r4/6B1/B7/3R4 w - e6"
+        )
+        self.stockfish.send_command("go depth 18")
+
+        self.stockfish.expect("* score mate 1 * pv d5e6")
+        self.stockfish.equals("bestmove d5e6")
+
+    def test_fen_position_mate_minus_1(self):
+        self.stockfish.send_command("ucinewgame")
+        self.stockfish.send_command(
+            "position fen 2brrb2/8/p7/Q7/1p1kpPp1/1P1pN1K1/3P4/8 b - -"
+        )
+        self.stockfish.send_command("go depth 18")
+        self.stockfish.expect("* score mate -1 *")
+        self.stockfish.starts_with("bestmove")
+
+    def test_fen_position_fixed_node(self):
+        self.stockfish.send_command("ucinewgame")
+        self.stockfish.send_command(
+            "position fen 5K2/8/2P1P1Pk/6pP/3p2P1/1P6/3P4/8 w - - 0 1"
+        )
+        self.stockfish.send_command("go nodes 500000")
+        self.stockfish.starts_with("bestmove")
+
+    def test_fen_position_with_mate_go_depth(self):
+        self.stockfish.send_command("ucinewgame")
+        self.stockfish.send_command(
+            "position fen 8/5R2/2K1P3/4k3/8/b1PPpp1B/5p2/8 w - -"
+        )
+        self.stockfish.send_command("go depth 18 searchmoves c6d7")
+        self.stockfish.expect("* score mate 2 * pv c6d7 * f7f5")
+
+        self.stockfish.starts_with("bestmove")
+
+    def test_fen_position_with_mate_go_mate(self):
+        self.stockfish.send_command("ucinewgame")
+        self.stockfish.send_command(
+            "position fen 8/5R2/2K1P3/4k3/8/b1PPpp1B/5p2/8 w - -"
+        )
+        self.stockfish.send_command("go mate 2 searchmoves c6d7")
+        self.stockfish.expect("* score mate 2 * pv c6d7 *")
+
+        self.stockfish.starts_with("bestmove")
+
+    def test_fen_position_with_mate_go_nodes(self):
+        self.stockfish.send_command("ucinewgame")
+        self.stockfish.send_command(
+            "position fen 8/5R2/2K1P3/4k3/8/b1PPpp1B/5p2/8 w - -"
+        )
+        self.stockfish.send_command("go nodes 500000 searchmoves c6d7")
+        self.stockfish.expect("* score mate 2 * pv c6d7 * f7f5")
+
+        self.stockfish.starts_with("bestmove")
+
+    def test_fen_position_depth_27(self):
+        self.stockfish.send_command("ucinewgame")
+        self.stockfish.send_command(
+            "position fen r1b2r1k/pp1p2pp/2p5/2B1q3/8/8/P1PN2PP/R4RK1 w - - 0 18"
+        )
+        self.stockfish.send_command("go")
+        self.stockfish.contains("score mate 1")
+
+        self.stockfish.starts_with("bestmove")
+
+    def test_fen_position_with_mate_go_depth_and_promotion(self):
+        self.stockfish.send_command("ucinewgame")
+        self.stockfish.send_command(
+            "position fen 8/5R2/2K1P3/4k3/8/b1PPpp1B/5p2/8 w - - moves c6d7 f2f1q"
+        )
+        self.stockfish.send_command("go depth 18")
+        self.stockfish.expect("* score mate 1 * pv f7f5")
+        self.stockfish.starts_with("bestmove f7f5")
+
+    def test_fen_position_with_mate_go_depth_and_searchmoves(self):
+        self.stockfish.send_command("ucinewgame")
+        self.stockfish.send_command(
+            "position fen 8/5R2/2K1P3/4k3/8/b1PPpp1B/5p2/8 w - -"
+        )
+        self.stockfish.send_command("go depth 18 searchmoves c6d7")
+        self.stockfish.expect("* score mate 2 * pv c6d7 * f7f5")
+
+        self.stockfish.starts_with("bestmove c6d7")
+
+    def test_fen_position_with_moves_with_mate_go_depth_and_searchmoves(self):
+        self.stockfish.send_command("ucinewgame")
+        self.stockfish.send_command(
+            "position fen 8/5R2/2K1P3/4k3/8/b1PPpp1B/5p2/8 w - - moves c6d7"
+        )
+        self.stockfish.send_command("go depth 18 searchmoves e3e2")
+        self.stockfish.expect("* score mate -1 * pv e3e2 f7f5")
+        self.stockfish.starts_with("bestmove e3e2")
+
+    def test_verify_nnue_network(self):
+        current_path = os.path.abspath(os.getcwd())
+        Stockfish(
+            f"export_net {os.path.join(current_path , 'verify.nnue')}".split(" "), True
+        )
+
+        self.stockfish.send_command("setoption name EvalFile value verify.nnue")
+        self.stockfish.send_command("position startpos")
+        self.stockfish.send_command("go depth 5")
+        self.stockfish.starts_with("bestmove")
+
+    def test_multipv_setting(self):
+        self.stockfish.send_command("setoption name MultiPV value 4")
+        self.stockfish.send_command("position startpos")
+        self.stockfish.send_command("go depth 5")
+        self.stockfish.starts_with("bestmove")
+
+    def test_fen_position_with_skill_level(self):
+        self.stockfish.send_command("setoption name Skill Level value 10")
+        self.stockfish.send_command("position startpos")
+        self.stockfish.send_command("go depth 5")
+        self.stockfish.starts_with("bestmove")
+
+        self.stockfish.send_command("setoption name Skill Level value 20")
+
+
+class TestSyzygy(metaclass=OrderedClassMembers):
+    def beforeAll(self):
+        self.stockfish = Stockfish()
+
+    def afterAll(self):
+        self.stockfish.quit()
+        assert self.stockfish.close() == 0
+
+    def afterEach(self):
+        assert postfix_check(self.stockfish.get_output()) == True
+        self.stockfish.clear_output()
+
+    def test_syzygy_setup(self):
+        self.stockfish.starts_with("Stockfish")
+        self.stockfish.send_command("uci")
+        self.stockfish.send_command(
+            f"setoption name SyzygyPath value {os.path.join(PATH, 'syzygy')}"
+        )
+        self.stockfish.expect(
+            "info string Found 35 WDL and 35 DTZ tablebase files (up to 4-man)."
+        )
+
+    def test_syzygy_bench(self):
+        self.stockfish.send_command("bench 128 1 8 default depth")
+        self.stockfish.expect("Nodes searched  :*")
+
+    def test_syzygy_position(self):
+        self.stockfish.send_command("ucinewgame")
+        self.stockfish.send_command("position fen 4k3/PP6/8/8/8/8/8/4K3 w - - 0 1")
+        self.stockfish.send_command("go depth 5")
+
+        def check_output(output):
+            if "score cp 20000" in output or "score mate" in output:
+                return True
+
+        self.stockfish.check_output(check_output)
+        self.stockfish.expect("bestmove *")
+
+    def test_syzygy_position_2(self):
+        self.stockfish.send_command("ucinewgame")
+        self.stockfish.send_command("position fen 8/1P6/2B5/8/4K3/8/6k1/8 w - - 0 1")
+        self.stockfish.send_command("go depth 5")
+
+        def check_output(output):
+            if "score cp 20000" in output or "score mate" in output:
+                return True
+
+        self.stockfish.check_output(check_output)
+        self.stockfish.expect("bestmove *")
+
+    def test_syzygy_position_3(self):
+        self.stockfish.send_command("ucinewgame")
+        self.stockfish.send_command("position fen 8/1P6/2B5/8/4K3/8/6k1/8 b - - 0 1")
+        self.stockfish.send_command("go depth 5")
+
+        def check_output(output):
+            if "score cp -20000" in output or "score mate" in output:
+                return True
+
+        self.stockfish.check_output(check_output)
+        self.stockfish.expect("bestmove *")
+
+
+def parse_args():
+    parser = argparse.ArgumentParser(description="Run Stockfish with testing options")
+    parser.add_argument("--valgrind", action="store_true", help="Run valgrind testing")
+    parser.add_argument(
+        "--valgrind-thread", action="store_true", help="Run valgrind-thread testing"
+    )
+    parser.add_argument(
+        "--sanitizer-undefined",
+        action="store_true",
+        help="Run sanitizer-undefined testing",
+    )
+    parser.add_argument(
+        "--sanitizer-thread", action="store_true", help="Run sanitizer-thread testing"
+    )
+
+    parser.add_argument(
+        "--none", action="store_true", help="Run without any testing options"
+    )
+    parser.add_argument("stockfish_path", type=str, help="Path to Stockfish binary")
+
+    return parser.parse_args()
+
+
+if __name__ == "__main__":
+    args = parse_args()
+
+    EPD.create_bench_epd()
+    TSAN.set_tsan_option()
+    Syzygy.download_syzygy()
+
+    framework = MiniTestFramework()
+
+    # Each test suite will be ran inside a temporary directory
+    framework.run([TestCLI, TestInteractive, TestSyzygy])
+
+    EPD.delete_bench_epd()
+    TSAN.unset_tsan_option()
+
+    if framework.has_failed():
+        sys.exit(1)
+
+    sys.exit(0)

tests/instrumented.sh

@@ -1,301 +0,0 @@
-#!/bin/bash
-# check for errors under Valgrind or sanitizers.
-
-error()
-{
-  echo "instrumented testing failed on line $1"
-  exit 1
-}
-trap 'error ${LINENO}' ERR
-
-# define suitable post and prefixes for testing options
-case $1 in
-  --valgrind)
-    echo "valgrind testing started"
-    prefix=''
-    exeprefix='valgrind --error-exitcode=42 --errors-for-leak-kinds=all --leak-check=full'
-    postfix=''
-    threads="1"
-  ;;
-  --valgrind-thread)
-    echo "valgrind-thread testing started"
-    prefix=''
-    exeprefix='valgrind --fair-sched=try --error-exitcode=42'
-    postfix=''
-    threads="2"
-  ;;
-  --sanitizer-undefined)
-    echo "sanitizer-undefined testing started"
-    prefix='!'
-    exeprefix=''
-    postfix='2>&1 | grep -A50 "runtime error:"'
-    threads="1"
-  ;;
-  --sanitizer-thread)
-    echo "sanitizer-thread testing started"
-    prefix='!'
-    exeprefix=''
-    postfix='2>&1 | grep -A50 "WARNING: ThreadSanitizer:"'
-    threads="2"
-
-cat << EOF > tsan.supp
-race:Stockfish::TTEntry::read
-race:Stockfish::TTEntry::save
-
-race:Stockfish::TranspositionTable::probe
-race:Stockfish::TranspositionTable::hashfull
-
-EOF
-
-    export TSAN_OPTIONS="suppressions=./tsan.supp"
-
-  ;;
-  *)
-    echo "unknown testing started"
-    prefix=''
-    exeprefix=''
-    postfix=''
-    threads="1"
-  ;;
-esac
-
-cat << EOF > bench_tmp.epd
-Rn6/1rbq1bk1/2p2n1p/2Bp1p2/3Pp1pP/1N2P1P1/2Q1NPB1/6K1 w - - 2 26
-rnbqkb1r/ppp1pp2/5n1p/3p2p1/P2PP3/5P2/1PP3PP/RNBQKBNR w KQkq - 0 3
-3qnrk1/4bp1p/1p2p1pP/p2bN3/1P1P1B2/P2BQ3/5PP1/4R1K1 w - - 9 28
-r4rk1/1b2ppbp/pq4pn/2pp1PB1/1p2P3/1P1P1NN1/1PP3PP/R2Q1RK1 w - - 0 13
-EOF
-
-# simple command line testing
-for args in "eval" \
-            "go nodes 1000" \
-            "go depth 10" \
-            "go perft 4" \
-            "go movetime 1000" \
-            "go wtime 8000 btime 8000 winc 500 binc 500" \
-            "go wtime 1000 btime 1000 winc 0 binc 0" \
-            "go wtime 1000 btime 1000 winc 0 binc 0" \
-            "go wtime 1000 btime 1000 winc 0 binc 0 movestogo 5" \
-            "go movetime 200" \
-            "go nodes 20000 searchmoves e2e4 d2d4" \
-            "bench 128 $threads 8 default depth" \
-            "bench 128 $threads 3 bench_tmp.epd depth" \
-            "export_net verify.nnue" \
-            "d" \
-            "compiler" \
-            "license" \
-            "uci"
-do
-
-   echo "$prefix $exeprefix ./stockfish $args $postfix"
-   eval "$prefix $exeprefix ./stockfish $args $postfix"
-
-done
-
-# verify the generated net equals the base net
-network=`./stockfish uci | grep 'option name EvalFile type string default' | awk '{print $NF}'`
-echo "Comparing $network to the written verify.nnue"
-diff $network verify.nnue
-
-# more general testing, following an uci protocol exchange
-cat << EOF > game.exp
- set timeout 240
- # to correctly catch eof we need the following line
- # expect_before timeout { exit 2 } eof { exit 3 }
- expect_before timeout { exit 2 }
-
- spawn $exeprefix ./stockfish
- expect "Stockfish"
-
- send "uci\n"
- expect "uciok"
-
- # send "setoption name Debug Log File value debug.log\n"
- send "setoption name Threads value $threads\n"
-
- send "ucinewgame\n"
- send "position startpos\n"
- send "go nodes 1000\n"
- expect "bestmove"
-
- send "ucinewgame\n"
- send "position startpos moves e2e4 e7e6\n"
- send "go nodes 1000\n"
- expect "bestmove"
-
- send "ucinewgame\n"
- send "position fen 5rk1/1K4p1/8/8/3B4/8/8/8 b - - 0 1\n"
- send "go depth 10\n"
- expect "bestmove"
-
- send "ucinewgame\n"
- send "position fen 5rk1/1K4p1/8/8/3B4/8/8/8 b - - 0 1\n"
- send "flip\n"
- send "go depth 10\n"
- expect "bestmove"
-
- send "ucinewgame\n"
- send "position startpos\n"
- send "go depth 5\n"
- expect -re {info depth \d+ seldepth \d+ multipv \d+ score cp \d+ nodes \d+ nps \d+ hashfull \d+ tbhits \d+ time \d+ pv}
- expect "bestmove"
-
- send "ucinewgame\n"
- send "setoption name UCI_ShowWDL value true\n"
- send "position startpos\n"
- send "go depth 9\n"
- expect -re {info depth 1 seldepth \d+ multipv \d+ score cp \d+ wdl \d+ \d+ \d+ nodes \d+ nps \d+ hashfull \d+ tbhits \d+ time \d+ pv}
- expect -re {info depth 2 seldepth \d+ multipv \d+ score cp \d+ wdl \d+ \d+ \d+ nodes \d+ nps \d+ hashfull \d+ tbhits \d+ time \d+ pv}
- expect -re {info depth 3 seldepth \d+ multipv \d+ score cp \d+ wdl \d+ \d+ \d+ nodes \d+ nps \d+ hashfull \d+ tbhits \d+ time \d+ pv}
- expect -re {info depth 4 seldepth \d+ multipv \d+ score cp \d+ wdl \d+ \d+ \d+ nodes \d+ nps \d+ hashfull \d+ tbhits \d+ time \d+ pv}
- expect -re {info depth 5 seldepth \d+ multipv \d+ score cp \d+ wdl \d+ \d+ \d+ nodes \d+ nps \d+ hashfull \d+ tbhits \d+ time \d+ pv}
- expect -re {info depth 6 seldepth \d+ multipv \d+ score cp \d+ wdl \d+ \d+ \d+ nodes \d+ nps \d+ hashfull \d+ tbhits \d+ time \d+ pv}
- expect -re {info depth 7 seldepth \d+ multipv \d+ score cp \d+ wdl \d+ \d+ \d+ nodes \d+ nps \d+ hashfull \d+ tbhits \d+ time \d+ pv}
- expect -re {info depth 8 seldepth \d+ multipv \d+ score cp \d+ wdl \d+ \d+ \d+ nodes \d+ nps \d+ hashfull \d+ tbhits \d+ time \d+ pv}
- expect -re {info depth 9 seldepth \d+ multipv \d+ score cp \d+ wdl \d+ \d+ \d+ nodes \d+ nps \d+ hashfull \d+ tbhits \d+ time \d+ pv}
- expect "bestmove"
-
- send "setoption name Clear Hash\n"
-
- send "ucinewgame\n"
- send "position fen 5K2/8/2qk4/2nPp3/3r4/6B1/B7/3R4 w - e6\n"
- send "go depth 18\n"
- expect "score mate 1"
- expect "pv d5e6"
- expect "bestmove d5e6"
-
- send "ucinewgame\n"
- send "position fen 2brrb2/8/p7/Q7/1p1kpPp1/1P1pN1K1/3P4/8 b - -\n"
- send "go depth 18\n"
- expect "score mate -1"
- expect "bestmove"
-
- send "ucinewgame\n"
- send "position fen 7K/P1p1p1p1/2P1P1Pk/6pP/3p2P1/1P6/3P4/8 w - - 0 1\n"
- send "go nodes 500000\n"
- expect "bestmove"
-
- send "ucinewgame\n"
- send "position fen 8/5R2/2K1P3/4k3/8/b1PPpp1B/5p2/8 w - -\n"
- send "go depth 18 searchmoves c6d7\n"
- expect "score mate 2 * pv c6d7 * f7f5"
- expect "bestmove c6d7"
-
- send "ucinewgame\n"
- send "position fen 8/5R2/2K1P3/4k3/8/b1PPpp1B/5p2/8 w - -\n"
- send "go mate 2 searchmoves c6d7\n"
- expect "score mate 2 * pv c6d7"
- expect "bestmove c6d7"
-
- send "ucinewgame\n"
- send "position fen 8/5R2/2K1P3/4k3/8/b1PPpp1B/5p2/8 w - -\n"
- send "go nodes 500000 searchmoves c6d7\n"
- expect "score mate 2 * pv c6d7 * f7f5"
- expect "bestmove c6d7"
-
- send "ucinewgame\n"
- send "position fen 1NR2B2/5p2/5p2/1p1kpp2/1P2rp2/2P1pB2/2P1P1K1/8 b - - \n"
- send "go depth 27\n"
- expect "score mate -2"
- expect "pv d5e6 c8d8"
- expect "bestmove d5e6"
-
- send "ucinewgame\n"
- send "position fen 8/5R2/2K1P3/4k3/8/b1PPpp1B/5p2/8 w - - moves c6d7 f2f1q\n"
- send "go depth 18\n"
- expect "score mate 1 * pv f7f5"
- expect "bestmove f7f5"
- 
- send "ucinewgame\n"
- send "position fen 8/5R2/2K1P3/4k3/8/b1PPpp1B/5p2/8 w - -\n"
- send "go depth 18 searchmoves c6d7\n"
- expect "score mate 2 * pv c6d7 * f7f5"
- expect "bestmove c6d7"
- 
- send "ucinewgame\n"
- send "position fen 8/5R2/2K1P3/4k3/8/b1PPpp1B/5p2/8 w - - moves c6d7\n"
- send "go depth 18 searchmoves e3e2\n"
- expect "score mate -1 * pv e3e2 f7f5"
- expect "bestmove e3e2"
-
- send "setoption name EvalFile value verify.nnue\n"
- send "position startpos\n"
- send "go depth 5\n"
- expect "bestmove"
-
- send "setoption name MultiPV value 4\n"
- send "position startpos\n"
- send "go depth 5\n"
- expect "bestmove"
-
- send "setoption name Skill Level value 10\n"
- send "position startpos\n"
- send "go depth 5\n"
- expect "bestmove"
- send "setoption name Skill Level value 20\n"
-
- send "quit\n"
- expect eof
-
- # return error code of the spawned program, useful for Valgrind
- lassign [wait] pid spawnid os_error_flag value
- exit \$value
-EOF
-
-#download TB as needed
-if [ ! -d ../tests/syzygy ]; then
-   curl -sL https://api.github.com/repos/niklasf/python-chess/tarball/9b9aa13f9f36d08aadfabff872882f4ab1494e95 | tar -xzf -
-   mv niklasf-python-chess-9b9aa13 ../tests/syzygy
-fi
-
-cat << EOF > syzygy.exp
- set timeout 240
- # to correctly catch eof we need the following line
- # expect_before timeout { exit 2 } eof { exit 3 }
- expect_before timeout { exit 2 }
- spawn $exeprefix ./stockfish
- expect "Stockfish"
- send "uci\n"
- send "setoption name SyzygyPath value ../tests/syzygy/\n"
- expect "info string Found 35 WDL and 35 DTZ tablebase files (up to 4-man)."
- send "bench 128 1 8 default depth\n"
- expect "Nodes searched  :"
- send "ucinewgame\n"
- send "position fen 4k3/PP6/8/8/8/8/8/4K3 w - - 0 1\n"
- send "go depth 5\n"
- expect -re {score cp 20000|score mate}
- expect "bestmove"
- send "ucinewgame\n"
- send "position fen 8/1P6/2B5/8/4K3/8/6k1/8 w - - 0 1\n"
- send "go depth 5\n"
- expect -re {score cp 20000|score mate}
- expect "bestmove"
- send "ucinewgame\n"
- send "position fen 8/1P6/2B5/8/4K3/8/6k1/8 b - - 0 1\n"
- send "go depth 5\n"
- expect -re {score cp -20000|score mate}
- expect "bestmove"
- send "quit\n"
- expect eof
-
- # return error code of the spawned program, useful for Valgrind
- lassign [wait] pid spawnid os_error_flag value
- exit \$value
-EOF
-
-for exp in game.exp syzygy.exp
-do
-
-  echo "======== $exp =============="
-  cat $exp
-  echo "============================"
-  echo "$prefix expect $exp $postfix"
-  eval "$prefix expect $exp $postfix"
-
-  rm $exp
-
-done
-
-rm -f tsan.supp bench_tmp.epd
-
-echo "instrumented testing OK"

tests/perft.sh

@@ -1,5 +1,7 @@
 #!/bin/bash
-# verify perft numbers (positions from www.chessprogramming.org/Perft_Results)
+# verify perft numbers (positions from https://www.chessprogramming.org/Perft_Results)
+
+TESTS_FAILED=0
 
 error()
 {
@@ -10,23 +12,82 @@ trap 'error ${LINENO}' ERR
 
 echo "perft testing started"
 
-cat << EOF > perft.exp
-   set timeout 10
-   lassign \$argv pos depth result
-   spawn ./stockfish
-   send "position \$pos\\ngo perft \$depth\\n"
-   expect "Nodes searched? \$result" {} timeout {exit 1}
-   send "quit\\n"
-   expect eof
+EXPECT_SCRIPT=$(mktemp)
+
+cat << 'EOF' > $EXPECT_SCRIPT
+#!/usr/bin/expect -f
+set timeout 30
+lassign [lrange $argv 0 4] pos depth result chess960 logfile
+log_file -noappend $logfile
+spawn ./stockfish
+if {$chess960 == "true"} {
+  send "setoption name UCI_Chess960 value true\n"
+}
+send "position $pos\ngo perft $depth\n"
+expect {
+  "Nodes searched: $result" {}
+  timeout {puts "TIMEOUT: Expected $result nodes"; exit 1}
+  eof {puts "EOF: Stockfish crashed"; exit 2}
+}
+send "quit\n"
+expect eof
 EOF
 
-expect perft.exp startpos 5 4865609 > /dev/null
-expect perft.exp "fen r3k2r/p1ppqpb1/bn2pnp1/3PN3/1p2P3/2N2Q1p/PPPBBPPP/R3K2R w KQkq -" 5 193690690 > /dev/null
-expect perft.exp "fen 8/2p5/3p4/KP5r/1R3p1k/8/4P1P1/8 w - -" 6 11030083 > /dev/null
-expect perft.exp "fen r3k2r/Pppp1ppp/1b3nbN/nP6/BBP1P3/q4N2/Pp1P2PP/R2Q1RK1 w kq - 0 1" 5 15833292 > /dev/null
-expect perft.exp "fen rnbq1k1r/pp1Pbppp/2p5/8/2B5/8/PPP1NnPP/RNBQK2R w KQ - 1 8" 5 89941194 > /dev/null
-expect perft.exp "fen r4rk1/1pp1qppp/p1np1n2/2b1p1B1/2B1P1b1/P1NP1N2/1PP1QPPP/R4RK1 w - - 0 10" 5 164075551 > /dev/null
+chmod +x $EXPECT_SCRIPT
 
-rm perft.exp
+run_test() {
+  local pos="$1"
+  local depth="$2"
+  local expected="$3"
+  local chess960="$4"
+  local tmp_file=$(mktemp)
 
-echo "perft testing OK"
+  echo -n "Testing depth $depth: ${pos:0:40}... "
+
+  if $EXPECT_SCRIPT "$pos" "$depth" "$expected" "$chess960" "$tmp_file" > /dev/null 2>&1; then
+    echo "OK"
+    rm -f "$tmp_file"
+  else
+    local exit_code=$?
+    echo "FAILED (exit code: $exit_code)"
+    echo "===== Output for failed test ====="
+    cat "$tmp_file"
+    echo "=================================="
+    rm -f "$tmp_file"
+    TESTS_FAILED=1
+  fi
+}
+
+# standard positions
+
+run_test "startpos" 7 3195901860 "false"
+run_test "fen r3k2r/p1ppqpb1/bn2pnp1/3PN3/1p2P3/2N2Q1p/PPPBBPPP/R3K2R w KQkq -" 5 193690690 "false"
+run_test "fen 8/2p5/3p4/KP5r/1R3p1k/8/4P1P1/8 w - -" 7 178633661 "false"
+run_test "fen r3k2r/Pppp1ppp/1b3nbN/nP6/BBP1P3/q4N2/Pp1P2PP/R2Q1RK1 w kq - 0 1" 6 706045033 "false"
+run_test "fen rnbq1k1r/pp1Pbppp/2p5/8/2B5/8/PPP1NnPP/RNBQK2R w KQ - 1 8" 5 89941194 "false"
+run_test "fen r4rk1/1pp1qppp/p1np1n2/2b1p1B1/2B1P1b1/P1NP1N2/1PP1QPPP/R4RK1 w - - 0 10" 5 164075551 "false"
+run_test "fen r7/4p3/5p1q/3P4/4pQ2/4pP2/6pp/R3K1kr w Q - 1 3" 5 11609488 "false"
+
+# chess960 positions
+
+run_test "fen rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR w AHah - 0 1" 6 119060324 "true"
+run_test "fen 1rqbkrbn/1ppppp1p/1n6/p1N3p1/8/2P4P/PP1PPPP1/1RQBKRBN w FBfb - 0 9" 6 191762235 "true"
+run_test "fen rbbqn1kr/pp2p1pp/6n1/2pp1p2/2P4P/P7/BP1PPPP1/R1BQNNKR w HAha - 0 9" 6 924181432 "true"
+run_test "fen rqbbknr1/1ppp2pp/p5n1/4pp2/P7/1PP5/1Q1PPPPP/R1BBKNRN w GAga - 0 9" 6 308553169 "true"
+run_test "fen 4rrb1/1kp3b1/1p1p4/pP1Pn2p/5p2/1PR2P2/2P1NB1P/2KR1B2 w D - 0 21" 6 872323796 "true"
+run_test "fen 1rkr3b/1ppn3p/3pB1n1/6q1/R2P4/4N1P1/1P5P/2KRQ1B1 b Dbd - 0 14" 6 2678022813 "true"
+run_test "fen qbbnrkr1/p1pppppp/1p4n1/8/2P5/6N1/PPNPPPPP/1BRKBRQ1 b FCge - 1 3" 6 521301336 "true"
+run_test "fen rr6/2kpp3/1ppn2p1/p2b1q1p/P4P1P/1PNN2P1/2PP4/1K2R2R b E - 1 20" 2 1438 "true"
+run_test "fen rr6/2kpp3/1ppn2p1/p2b1q1p/P4P1P/1PNN2P1/2PP4/1K2RR2 w E - 0 20" 3 37340 "true"
+run_test "fen rr6/2kpp3/1ppnb1p1/p2Q1q1p/P4P1P/1PNN2P1/2PP4/1K2RR2 b E - 2 19" 4 2237725 "true"
+run_test "fen rr6/2kpp3/1ppnb1p1/p4q1p/P4P1P/1PNN2P1/2PP2Q1/1K2RR2 w E - 1 19" 4 2098209 "true"
+run_test "fen rr6/2kpp3/1ppnb1p1/p4q1p/P4P1P/1PNN2P1/2PP2Q1/1K2RR2 w E - 1 19" 5 79014522 "true"
+run_test "fen rr6/2kpp3/1ppnb1p1/p4q1p/P4P1P/1PNN2P1/2PP2Q1/1K2RR2 w E - 1 19" 6 2998685421 "true"
+
+rm -f $EXPECT_SCRIPT
+echo "perft testing completed"
+
+if [ $TESTS_FAILED -ne 0 ]; then
+  echo "Some tests failed"
+  exit 1
+fi

tests/testing.py

@@ -0,0 +1,400 @@
+import subprocess
+from typing import List
+import os
+import collections
+import time
+import sys
+import traceback
+import fnmatch
+from functools import wraps
+from contextlib import redirect_stdout
+import io
+import tarfile
+import pathlib
+import concurrent.futures
+import tempfile
+import shutil
+import requests
+
+CYAN_COLOR = "\033[36m"
+GRAY_COLOR = "\033[2m"
+RED_COLOR = "\033[31m"
+GREEN_COLOR = "\033[32m"
+RESET_COLOR = "\033[0m"
+WHITE_BOLD = "\033[1m"
+
+MAX_TIMEOUT = 60 * 5
+
+PATH = pathlib.Path(__file__).parent.resolve()
+
+
+class Valgrind:
+    @staticmethod
+    def get_valgrind_command():
+        return [
+            "valgrind",
+            "--error-exitcode=42",
+            "--errors-for-leak-kinds=all",
+            "--leak-check=full",
+        ]
+
+    @staticmethod
+    def get_valgrind_thread_command():
+        return ["valgrind", "--error-exitcode=42", "--fair-sched=try"]
+
+
+class TSAN:
+    @staticmethod
+    def set_tsan_option():
+        with open(f"tsan.supp", "w") as f:
+            f.write(
+                """
+race:Stockfish::TTEntry::read
+race:Stockfish::TTEntry::save
+race:Stockfish::TranspositionTable::probe
+race:Stockfish::TranspositionTable::hashfull
+"""
+            )
+
+        os.environ["TSAN_OPTIONS"] = "suppressions=./tsan.supp"
+
+    @staticmethod
+    def unset_tsan_option():
+        os.environ.pop("TSAN_OPTIONS", None)
+        os.remove(f"tsan.supp")
+
+
+class EPD:
+    @staticmethod
+    def create_bench_epd():
+        with open(f"{os.path.join(PATH,'bench_tmp.epd')}", "w") as f:
+            f.write(
+                """
+Rn6/1rbq1bk1/2p2n1p/2Bp1p2/3Pp1pP/1N2P1P1/2Q1NPB1/6K1 w - - 2 26
+rnbqkb1r/ppp1pp2/5n1p/3p2p1/P2PP3/5P2/1PP3PP/RNBQKBNR w KQkq - 0 3
+3qnrk1/4bp1p/1p2p1pP/p2bN3/1P1P1B2/P2BQ3/5PP1/4R1K1 w - - 9 28
+r4rk1/1b2ppbp/pq4pn/2pp1PB1/1p2P3/1P1P1NN1/1PP3PP/R2Q1RK1 w - - 0 13
+"""
+            )
+
+    @staticmethod
+    def delete_bench_epd():
+        os.remove(f"{os.path.join(PATH,'bench_tmp.epd')}")
+
+
+class Syzygy:
+    @staticmethod
+    def get_syzygy_path():
+        return os.path.abspath("syzygy")
+
+    @staticmethod
+    def download_syzygy():
+        if not os.path.isdir(os.path.join(PATH, "syzygy")):
+            url = "https://api.github.com/repos/niklasf/python-chess/tarball/9b9aa13f9f36d08aadfabff872882f4ab1494e95"
+            file = "niklasf-python-chess-9b9aa13"
+
+            with tempfile.TemporaryDirectory() as tmpdirname:
+                tarball_path = os.path.join(tmpdirname, f"{file}.tar.gz")
+
+                response = requests.get(url, stream=True)
+                with open(tarball_path, "wb") as f:
+                    for chunk in response.iter_content(chunk_size=8192):
+                        f.write(chunk)
+
+                with tarfile.open(tarball_path, "r:gz") as tar:
+                    tar.extractall(tmpdirname)
+
+                shutil.move(
+                    os.path.join(tmpdirname, file), os.path.join(PATH, "syzygy")
+                )
+
+
+class OrderedClassMembers(type):
+    @classmethod
+    def __prepare__(self, name, bases):
+        return collections.OrderedDict()
+
+    def __new__(self, name, bases, classdict):
+        classdict["__ordered__"] = [
+            key for key in classdict.keys() if key not in ("__module__", "__qualname__")
+        ]
+        return type.__new__(self, name, bases, classdict)
+
+
+class TimeoutException(Exception):
+    def __init__(self, message: str, timeout: int):
+        self.message = message
+        self.timeout = timeout
+
+
+def timeout_decorator(timeout: float):
+    def decorator(func):
+        @wraps(func)
+        def wrapper(*args, **kwargs):
+            with concurrent.futures.ThreadPoolExecutor() as executor:
+                future = executor.submit(func, *args, **kwargs)
+                try:
+                    result = future.result(timeout=timeout)
+                except concurrent.futures.TimeoutError:
+                    raise TimeoutException(
+                        f"Function {func.__name__} timed out after {timeout} seconds",
+                        timeout,
+                    )
+            return result
+
+        return wrapper
+
+    return decorator
+
+
+class MiniTestFramework:
+    def __init__(self):
+        self.passed_test_suites = 0
+        self.failed_test_suites = 0
+        self.passed_tests = 0
+        self.failed_tests = 0
+        self.stop_on_failure = True
+
+    def has_failed(self) -> bool:
+        return self.failed_test_suites > 0
+
+    def run(self, classes: List[type]) -> bool:
+        self.start_time = time.time()
+
+        for test_class in classes:
+            with tempfile.TemporaryDirectory() as tmpdirname:
+                original_cwd = os.getcwd()
+                os.chdir(tmpdirname)
+
+                try:
+                    if self.__run(test_class):
+                        self.failed_test_suites += 1
+                    else:
+                        self.passed_test_suites += 1
+                except Exception as e:
+                    self.failed_test_suites += 1
+                    print(f"\n{RED_COLOR}Error: {e}{RESET_COLOR}")
+                finally:
+                    os.chdir(original_cwd)
+
+        self.__print_summary(round(time.time() - self.start_time, 2))
+        return self.has_failed()
+
+    def __run(self, test_class) -> bool:
+        test_instance = test_class()
+        test_name = test_instance.__class__.__name__
+        test_methods = [m for m in test_instance.__ordered__ if m.startswith("test_")]
+
+        print(f"\nTest Suite: {test_name}")
+
+        if hasattr(test_instance, "beforeAll"):
+            test_instance.beforeAll()
+
+        fails = 0
+
+        for method in test_methods:
+            fails += self.__run_test_method(test_instance, method)
+
+        if hasattr(test_instance, "afterAll"):
+            test_instance.afterAll()
+
+        self.failed_tests += fails
+
+        return fails > 0
+
+    def __run_test_method(self, test_instance, method: str) -> int:
+        print(f"    Running {method}... \r", end="", flush=True)
+
+        buffer = io.StringIO()
+        fails = 0
+
+        try:
+            t0 = time.time()
+
+            with redirect_stdout(buffer):
+                if hasattr(test_instance, "beforeEach"):
+                    test_instance.beforeEach()
+
+                getattr(test_instance, method)()
+
+                if hasattr(test_instance, "afterEach"):
+                    test_instance.afterEach()
+
+            duration = time.time() - t0
+
+            self.print_success(f" {method} ({duration * 1000:.2f}ms)")
+            self.passed_tests += 1
+        except Exception as e:
+            if isinstance(e, TimeoutException):
+                self.print_failure(
+                    f" {method} (hit execution limit of {e.timeout} seconds)"
+                )
+
+            if isinstance(e, AssertionError):
+                self.__handle_assertion_error(t0, method)
+
+            if self.stop_on_failure:
+                self.__print_buffer_output(buffer)
+                raise e
+
+            fails += 1
+        finally:
+            self.__print_buffer_output(buffer)
+
+        return fails
+
+    def __handle_assertion_error(self, start_time, method: str):
+        duration = time.time() - start_time
+        self.print_failure(f" {method} ({duration * 1000:.2f}ms)")
+        traceback_output = "".join(traceback.format_tb(sys.exc_info()[2]))
+
+        colored_traceback = "\n".join(
+            f"  {CYAN_COLOR}{line}{RESET_COLOR}"
+            for line in traceback_output.splitlines()
+        )
+
+        print(colored_traceback)
+
+    def __print_buffer_output(self, buffer: io.StringIO):
+        output = buffer.getvalue()
+        if output:
+            indented_output = "\n".join(f"    {line}" for line in output.splitlines())
+            print(f"    {RED_COLOR}⎯⎯⎯⎯⎯OUTPUT⎯⎯⎯⎯⎯{RESET_COLOR}")
+            print(f"{GRAY_COLOR}{indented_output}{RESET_COLOR}")
+            print(f"    {RED_COLOR}⎯⎯⎯⎯⎯OUTPUT⎯⎯⎯⎯⎯{RESET_COLOR}")
+
+    def __print_summary(self, duration: float):
+        print(f"\n{WHITE_BOLD}Test Summary{RESET_COLOR}\n")
+        print(
+            f"    Test Suites: {GREEN_COLOR}{self.passed_test_suites} passed{RESET_COLOR}, {RED_COLOR}{self.failed_test_suites} failed{RESET_COLOR}, {self.passed_test_suites + self.failed_test_suites} total"
+        )
+        print(
+            f"    Tests:       {GREEN_COLOR}{self.passed_tests} passed{RESET_COLOR}, {RED_COLOR}{self.failed_tests} failed{RESET_COLOR}, {self.passed_tests + self.failed_tests} total"
+        )
+        print(f"    Time:        {duration}s\n")
+
+    def print_failure(self, add: str):
+        print(f"    {RED_COLOR}✗{RESET_COLOR}{add}", flush=True)
+
+    def print_success(self, add: str):
+        print(f"    {GREEN_COLOR}✓{RESET_COLOR}{add}", flush=True)
+
+
+class Stockfish:
+    def __init__(
+        self,
+        prefix: List[str],
+        path: str,
+        args: List[str] = [],
+        cli: bool = False,
+    ):
+        self.path = path
+        self.process = None
+        self.args = args
+        self.cli = cli
+        self.prefix = prefix
+        self.output = []
+
+        self.start()
+
+    def _check_process_alive(self):
+        if not self.process or self.process.poll() is not None:
+            print("\n".join(self.output))
+            raise RuntimeError("Stockfish process has terminated")
+
+    def start(self):
+        if self.cli:
+            self.process = subprocess.run(
+                self.prefix + [self.path] + self.args,
+                capture_output=True,
+                text=True,
+            )
+
+            if self.process.returncode != 0:
+                print(self.process.stdout)
+                print(self.process.stderr)
+                print(f"Process failed with return code {self.process.returncode}")
+
+            return
+
+        self.process = subprocess.Popen(
+            self.prefix + [self.path] + self.args,
+            stdin=subprocess.PIPE,
+            stdout=subprocess.PIPE,
+            stderr=subprocess.STDOUT,
+            universal_newlines=True,
+            bufsize=1,
+        )
+
+    def setoption(self, name: str, value: str):
+        self.send_command(f"setoption name {name} value {value}")
+
+    def send_command(self, command: str):
+        if not self.process:
+            raise RuntimeError("Stockfish process is not started")
+
+        self._check_process_alive()
+
+        self.process.stdin.write(command + "\n")
+        self.process.stdin.flush()
+
+    @timeout_decorator(MAX_TIMEOUT)
+    def equals(self, expected_output: str):
+        for line in self.readline():
+            if line == expected_output:
+                return
+
+    @timeout_decorator(MAX_TIMEOUT)
+    def expect(self, expected_output: str):
+        for line in self.readline():
+            if fnmatch.fnmatch(line, expected_output):
+                return
+
+    @timeout_decorator(MAX_TIMEOUT)
+    def contains(self, expected_output: str):
+        for line in self.readline():
+            if expected_output in line:
+                return
+
+    @timeout_decorator(MAX_TIMEOUT)
+    def starts_with(self, expected_output: str):
+        for line in self.readline():
+            if line.startswith(expected_output):
+                return
+
+    @timeout_decorator(MAX_TIMEOUT)
+    def check_output(self, callback):
+        if not callback:
+            raise ValueError("Callback function is required")
+
+        for line in self.readline():
+            if callback(line) == True:
+                return
+
+    def readline(self):
+        if not self.process:
+            raise RuntimeError("Stockfish process is not started")
+
+        while True:
+            self._check_process_alive()
+            line = self.process.stdout.readline().strip()
+            self.output.append(line)
+
+            yield line
+
+    def clear_output(self):
+        self.output = []
+
+    def get_output(self) -> List[str]:
+        return self.output
+
+    def quit(self):
+        self.send_command("quit")
+
+    def close(self):
+        if self.process:
+            self.process.stdin.close()
+            self.process.stdout.close()
+            return self.process.wait()
+
+        return 0