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72 lines
2.3 KiB
C++
72 lines
2.3 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) 2008-2012 Marco Costalba, Joona Kiiski, Tord Romstad
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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(HISTORY_H_INCLUDED)
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#define HISTORY_H_INCLUDED
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#include "types.h"
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#include <cstring>
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#include <algorithm>
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/// The History class stores statistics about how often different moves
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/// have been successful or unsuccessful during the current search. These
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/// statistics are used for reduction and move ordering decisions. History
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/// entries are stored according only to moving piece and destination square,
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/// in particular two moves with different origin but same destination and
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/// same piece will be considered identical.
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class History {
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public:
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void clear();
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Value value(Piece p, Square to) const;
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void add(Piece p, Square to, Value bonus);
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Value gain(Piece p, Square to) const;
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void update_gain(Piece p, Square to, Value g);
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static const Value MaxValue = Value(2000);
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private:
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Value history[16][64]; // [piece][to_square]
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Value maxGains[16][64]; // [piece][to_square]
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};
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inline void History::clear() {
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memset(history, 0, 16 * 64 * sizeof(Value));
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memset(maxGains, 0, 16 * 64 * sizeof(Value));
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}
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inline Value History::value(Piece p, Square to) const {
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return history[p][to];
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}
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inline void History::add(Piece p, Square to, Value bonus) {
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if (abs(history[p][to] + bonus) < MaxValue) history[p][to] += bonus;
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}
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inline Value History::gain(Piece p, Square to) const {
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return maxGains[p][to];
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}
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inline void History::update_gain(Piece p, Square to, Value g) {
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maxGains[p][to] = std::max(g, maxGains[p][to] - 1);
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}
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#endif // !defined(HISTORY_H_INCLUDED)
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