mirror of
https://github.com/sockspls/badfish
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100 lines
2.6 KiB
C++
100 lines
2.6 KiB
C++
/*
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Glaurung, a UCI chess playing engine.
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Copyright (C) 2004-2008 Tord Romstad
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Glaurung 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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Glaurung 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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////
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//// Includes
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////
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#include <cassert>
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#include "history.h"
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////
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//// Functions
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////
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/// Constructor
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History::History() {
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this->clear();
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}
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/// History::clear() clears the history tables.
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void History::clear() {
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memset(history, 0, 2 * 8 * 64 * sizeof(int));
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memset(successCount, 0, 2 * 8 * 64 * sizeof(int));
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memset(failureCount, 0, 2 * 8 * 64 * sizeof(int));
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}
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/// History::success() registers a move as being successful. This is done
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/// whenever a non-capturing move causes a beta cutoff in the main search.
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/// The three parameters are the moving piece, the move itself, and the
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/// search depth.
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void History::success(Piece p, Move m, Depth d) {
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assert(piece_is_ok(p));
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assert(move_is_ok(m));
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history[p][move_to(m)] += int(d) * int(d);
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successCount[p][move_to(m)]++;
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// Prevent history overflow:
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if(history[p][move_to(m)] >= HistoryMax)
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for(int i = 0; i < 16; i++)
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for(int j = 0; j < 64; j++)
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history[i][j] /= 2;
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}
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/// History::failure() registers a move as being unsuccessful. The function is
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/// called for each non-capturing move which failed to produce a beta cutoff
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/// at a node where a beta cutoff was finally found.
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void History::failure(Piece p, Move m) {
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assert(piece_is_ok(p));
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assert(move_is_ok(m));
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failureCount[p][move_to(m)]++;
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}
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/// History::move_ordering_score() returns an integer value used to order the
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/// non-capturing moves in the MovePicker class.
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int History::move_ordering_score(Piece p, Move m) const {
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assert(piece_is_ok(p));
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assert(move_is_ok(m));
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return history[p][move_to(m)];
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}
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/// History::ok_to_prune() decides whether a move has been sufficiently
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/// unsuccessful that it makes sense to prune it entirely.
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bool History::ok_to_prune(Piece p, Move m, Depth d) const {
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assert(piece_is_ok(p));
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assert(move_is_ok(m));
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return (int(d) * successCount[p][move_to(m)] < failureCount[p][move_to(m)]);
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}
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