/*
Stockfish, a UCI chess playing engine derived from Glaurung 2.1
Copyright (C) 2004-2008 Tord Romstad (Glaurung author)
- Copyright (C) 2008 Marco Costalba
+ Copyright (C) 2008-2009 Marco Costalba
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/>.
*/
//// Types
////
-/// 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.
+/// 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();
void clear();
- void success(Piece p, Move m, Depth d);
- void failure(Piece p, Move m);
- int move_ordering_score(Piece p, Move m) const;
- bool ok_to_prune(Piece p, Move m, Depth d) const;
+ void success(Piece p, Square to, Depth d);
+ void failure(Piece p, Square to);
+ int move_ordering_score(Piece p, Square to) const;
+ bool ok_to_prune(Piece p, Square to, Depth d) const;
private:
int history[16][64]; // [piece][square]
/// HistoryMax controls how often the history counters will be scaled down:
/// When the history score for a move gets bigger than HistoryMax, all
-/// entries in the table are divided by 2. It is difficult to guess what
-/// the ideal value of this constant is. Scaling down the scores often has
+/// entries in the table are divided by 2. It is difficult to guess what
+/// the ideal value of this constant is. Scaling down the scores often has
/// the effect that parts of the search tree which have been searched
/// recently have a bigger importance for move ordering than the moves which
/// have been searched a long time ago.
-///
-/// Note that HistoryMax should probably be changed whenever the constant
-/// OnePly in depth.h is changed. This is somewhat annoying. Perhaps it
-/// would be better to scale down the history table at regular intervals?
-const int HistoryMax = 50000;
+const int HistoryMax = 25000 * OnePly;
#endif // !defined(HISTORY_H_INCLUDED)