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Marco Costalba
e68ebe618c
And upon reentering the same position try it as first. Normally qsearch moves order is already very good, first move is the cut off in almost 90% of cases. With this patch, we get a cut off on TT move of 98%. Another good side effect is that we don't generate captures and/or checks when we already have a TT move. Unfortunatly we found a TT move only in 1% of cases. So real impact of this patch is relatively low. Signed-off-by: Marco Costalba <mcostalba@gmail.com>
121 lines
3.7 KiB
C++
121 lines
3.7 KiB
C++
/*
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Stockfish, a UCI chess playing engine derived from Glaurung 2.1
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Copyright (C) 2004-2008 Tord Romstad (Glaurung author)
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Copyright (C) 2008 Marco Costalba
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Stockfish is free software: you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation, either version 3 of the License, or
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(at your option) any later version.
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Stockfish is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program. If not, see <http://www.gnu.org/licenses/>.
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*/
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#if !defined MOVEPICK_H_INCLUDED
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#define MOVEPICK_H_INCLUDED
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////
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//// Includes
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////
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#include "depth.h"
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#include "lock.h"
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#include "position.h"
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////
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//// Types
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////
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struct EvalInfo;
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struct SearchStack;
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/// MovePicker is a class which is used to pick one legal move at a time from
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/// the current position. It is initialized with a Position object and a few
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/// moves we have reason to believe are good. The most important method is
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/// MovePicker::pick_next_move(), which returns a new legal move each time it
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/// is called, until there are no legal moves left, when MOVE_NONE is returned.
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/// In order to improve the efficiency of the alpha beta algorithm, MovePicker
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/// attempts to return the moves which are most likely to be strongest first.
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class MovePicker {
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MovePicker& operator=(const MovePicker&); // Silence a warning under MSVC
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public:
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enum MovegenPhase {
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PH_TT_MOVE, // Transposition table move
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PH_MATE_KILLER, // Mate killer from the current ply
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PH_GOOD_CAPTURES, // Queen promotions and captures with SEE values >= 0
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PH_BAD_CAPTURES, // Queen promotions and captures with SEE values < 0
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PH_KILLER_1, // Killer move 1 from the current ply (not used yet).
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PH_KILLER_2, // Killer move 2 from the current ply (not used yet).
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PH_NONCAPTURES, // Non-captures and underpromotions
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PH_EVASIONS, // Check evasions
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PH_QCAPTURES, // Captures in quiescence search
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PH_QCHECKS, // Checks in quiescence search
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PH_STOP
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};
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MovePicker(const Position& p, bool pvnode, Move ttm, const SearchStack& ss, Depth d);
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Move get_next_move();
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Move get_next_move(Lock &lock);
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int number_of_moves() const;
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int current_move_score() const;
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Bitboard discovered_check_candidates() const;
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static void init_phase_table();
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private:
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void score_captures();
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void score_noncaptures();
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void score_evasions();
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void score_qcaptures();
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Move pick_move_from_list();
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int find_best_index();
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int find_best_index(Bitboard* squares, int values[]);
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const Position& pos;
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Move ttMove, mateKiller, killer1, killer2;
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Bitboard pinned, dc;
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MoveStack moves[256], badCaptures[64];
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bool pvNode;
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Depth depth;
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int phaseIndex;
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int numOfMoves, numOfBadCaptures;
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int movesPicked;
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bool finished;
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};
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////
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//// Inline functions
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////
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/// MovePicker::number_of_moves() simply returns the numOfMoves member
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/// variable. It is intended to be used in positions where the side to move
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/// is in check, for detecting checkmates or situations where there is only
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/// a single reply to check.
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inline int MovePicker::number_of_moves() const {
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return numOfMoves;
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}
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/// MovePicker::discovered_check_candidates() returns a bitboard containing
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/// all pieces which can possibly give discovered check. This bitboard is
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/// computed by the constructor function.
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inline Bitboard MovePicker::discovered_check_candidates() const {
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return dc;
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}
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#endif // !defined(MOVEPICK_H_INCLUDED)
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