mirror of
https://github.com/sockspls/badfish
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436fa5c8fa
Both with added comment and changing the API to reflect that only destination square and moved piece is important for history. No functional change. Signed-off-by: Marco Costalba <mcostalba@gmail.com>
105 lines
2.7 KiB
C++
105 lines
2.7 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) 2008-2009 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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////
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//// Includes
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////
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#include <cassert>
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#include <cstring>
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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() { clear(); }
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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 destination square, and
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/// the search depth.
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void History::success(Piece p, Square to, Depth d) {
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assert(piece_is_ok(p));
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assert(square_is_ok(to));
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history[p][to] += int(d) * int(d);
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successCount[p][to]++;
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// Prevent history overflow
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if (history[p][to] >= 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, Square to) {
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assert(piece_is_ok(p));
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assert(square_is_ok(to));
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failureCount[p][to]++;
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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, Square to) const {
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assert(piece_is_ok(p));
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assert(square_is_ok(to));
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return history[p][to];
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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, Square to, Depth d) const {
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assert(piece_is_ok(p));
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assert(square_is_ok(to));
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return (int(d) * successCount[p][to] < failureCount[p][to]);
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}
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