2 Stockfish, a UCI chess playing engine derived from Glaurung 2.1
3 Copyright (C) 2004-2008 Tord Romstad (Glaurung author)
4 Copyright (C) 2008-2015 Marco Costalba, Joona Kiiski, Tord Romstad
5 Copyright (C) 2015-2016 Marco Costalba, Joona Kiiski, Gary Linscott, Tord Romstad
7 Stockfish is free software: you can redistribute it and/or modify
8 it under the terms of the GNU General Public License as published by
9 the Free Software Foundation, either version 3 of the License, or
10 (at your option) any later version.
12 Stockfish is distributed in the hope that it will be useful,
13 but WITHOUT ANY WARRANTY; without even the implied warranty of
14 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
15 GNU General Public License for more details.
17 You should have received a copy of the GNU General Public License
18 along with this program. If not, see <http://www.gnu.org/licenses/>.
21 #ifndef MOVEPICK_H_INCLUDED
22 #define MOVEPICK_H_INCLUDED
24 #include <algorithm> // For std::max
25 #include <cstring> // For std::memset
33 /// The Stats struct stores moves statistics. According to the template parameter
34 /// the class can store History and Countermoves. History records how often
35 /// different moves have been successful or unsuccessful during the current search
36 /// and is used for reduction and move ordering decisions.
37 /// Countermoves store the move that refute a previous one. Entries are stored
38 /// using only the moving piece and destination square, hence two moves with
39 /// different origin but same destination and piece will be considered identical.
40 template<typename T, bool CM = false>
43 static const Value Max = Value(1 << 28);
45 const T* operator[](Piece pc) const { return table[pc]; }
46 T* operator[](Piece pc) { return table[pc]; }
47 void clear() { std::memset(table, 0, sizeof(table)); }
49 void update(Piece pc, Square to, Move m) { table[pc][to] = m; }
51 void update(Piece pc, Square to, Value v) {
53 if (abs(int(v)) >= 324)
56 table[pc][to] -= table[pc][to] * abs(int(v)) / (CM ? 936 : 324);
57 table[pc][to] += int(v) * 32;
61 T table[PIECE_NB][SQUARE_NB];
64 typedef Stats<Move> MoveStats;
65 typedef Stats<Value, false> HistoryStats;
66 typedef Stats<Value, true> CounterMoveStats;
67 typedef Stats<CounterMoveStats> CounterMoveHistoryStats;
70 /// MovePicker class is used to pick one pseudo legal move at a time from the
71 /// current position. The most important method is next_move(), which returns a
72 /// new pseudo legal move each time it is called, until there are no moves left,
73 /// when MOVE_NONE is returned. In order to improve the efficiency of the alpha
74 /// beta algorithm, MovePicker attempts to return the moves which are most likely
75 /// to get a cut-off first.
79 MovePicker(const MovePicker&) = delete;
80 MovePicker& operator=(const MovePicker&) = delete;
82 MovePicker(const Position&, Move, Value);
83 MovePicker(const Position&, Move, Depth, Square);
84 MovePicker(const Position&, Move, Depth, Search::Stack*);
89 template<GenType> void score();
90 void generate_next_stage();
91 ExtMove* begin() { return moves; }
92 ExtMove* end() { return endMoves; }
95 const Search::Stack* ss;
100 Square recaptureSquare;
103 ExtMove *endQuiets, *endBadCaptures = moves + MAX_MOVES - 1;
104 ExtMove moves[MAX_MOVES], *cur = moves, *endMoves = moves;
107 #endif // #ifndef MOVEPICK_H_INCLUDED