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BadFish/src/history.h
Marco Costalba 877b468e3e Partially restore HistoryMax
Should be not useful but better safe than sorry.

No functional change.

Signed-off-by: Marco Costalba <mcostalba@gmail.com>
2011-01-15 11:31:14 +01:00

76 lines
2.4 KiB
C++

/*
Stockfish, a UCI chess playing engine derived from Glaurung 2.1
Copyright (C) 2004-2008 Tord Romstad (Glaurung author)
Copyright (C) 2008-2010 Marco Costalba, Joona Kiiski, Tord Romstad
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/>.
*/
#if !defined(HISTORY_H_INCLUDED)
#define HISTORY_H_INCLUDED
#include <cstring>
#include "depth.h"
#include "move.h"
#include "piece.h"
#include "value.h"
/// The History class stores statistics about how often different moves
/// have been successful or unsuccessful during the current search. These
/// statistics are used for reduction and move ordering decisions. History
/// entries are stored according only to moving piece and destination square,
/// in particular two moves with different origin but same destination and
/// same piece will be considered identical.
class History {
public:
History() { clear(); }
void clear();
int value(Piece p, Square to) const;
void update(Piece p, Square to, Value delta);
Value gain(Piece p, Square to) const;
void update_gain(Piece p, Square to, Value delta);
static const int MaxValue = (1 << 29); // To avoid an overflow
private:
Value history[16][64]; // [piece][to_square]
Value maxGains[16][64]; // [piece][to_square]
};
inline void History::clear() {
memset(history, 0, 16 * 64 * sizeof(int));
memset(maxGains, 0, 16 * 64 * sizeof(int));
}
inline int History::value(Piece p, Square to) const {
return history[p][to];
}
inline void History::update(Piece p, Square to, Value bonus) {
if (abs(history[p][to]) < MaxValue) history[p][to] += bonus;
}
inline Value History::gain(Piece p, Square to) const {
return maxGains[p][to];
}
inline void History::update_gain(Piece p, Square to, Value gain) {
maxGains[p][to] = (gain >= maxGains[p][to] ? gain : maxGains[p][to] - 1);
}
#endif // !defined(HISTORY_H_INCLUDED)