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
6 Stockfish is free software: you can redistribute it and/or modify
7 it under the terms of the GNU General Public License as published by
8 the Free Software Foundation, either version 3 of the License, or
9 (at your option) any later version.
11 Stockfish is distributed in the hope that it will be useful,
12 but WITHOUT ANY WARRANTY; without even the implied warranty of
13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 GNU General Public License for more details.
16 You should have received a copy of the GNU General Public License
17 along with this program. If not, see <http://www.gnu.org/licenses/>.
20 #ifndef MOVEPICK_H_INCLUDED
21 #define MOVEPICK_H_INCLUDED
23 #include <algorithm> // For std::max
24 #include <cstring> // For std::memset
32 /// The Stats struct stores moves statistics. According to the template parameter
33 /// the class can store History and Countermoves. History records how often
34 /// different moves have been successful or unsuccessful during the current search
35 /// and is used for reduction and move ordering decisions.
36 /// Countermoves store the move that refute a previous one. Entries are stored
37 /// using only the moving piece and destination square, hence two moves with
38 /// different origin but same destination and piece will be considered identical.
42 static const Value Max = Value(1<<28);
44 const T* operator[](Piece pc) const { return table[pc]; }
45 T* operator[](Piece pc) { return table[pc]; }
46 void clear() { std::memset(table, 0, sizeof(table)); }
48 void update(Piece pc, Square to, Move m) {
50 if (m != table[pc][to])
54 void update(Piece pc, Square to, Value v) {
56 table[pc][to] -= table[pc][to] * std::min(abs(int(v)), 512) / 512;
57 table[pc][to] += int(v) * 64;
61 T table[PIECE_NB][SQUARE_NB];
64 typedef Stats<Value> HistoryStats;
65 typedef Stats<Move> MovesStats;
66 typedef Stats<HistoryStats> CounterMovesHistoryStats;
69 /// MovePicker class is used to pick one pseudo legal move at a time from the
70 /// current position. The most important method is next_move(), which returns a
71 /// new pseudo legal move each time it is called, until there are no moves left,
72 /// when MOVE_NONE is returned. In order to improve the efficiency of the alpha
73 /// beta algorithm, MovePicker attempts to return the moves which are most likely
74 /// to get a cut-off first.
78 MovePicker(const MovePicker&) = delete;
79 MovePicker& operator=(const MovePicker&) = delete;
81 MovePicker(const Position&, Move, Depth, const HistoryStats&, const CounterMovesHistoryStats&, Square);
82 MovePicker(const Position&, Move, const HistoryStats&, const CounterMovesHistoryStats&, Value);
83 MovePicker(const Position&, Move, Depth, const HistoryStats&, const CounterMovesHistoryStats&, Move, Search::Stack*);
85 template<bool SpNode> Move next_move();
88 template<GenType> void score();
89 void generate_next_stage();
90 ExtMove* begin() { return moves; }
91 ExtMove* end() { return endMoves; }
94 const HistoryStats& history;
95 const CounterMovesHistoryStats& counterMovesHistory;
101 Square recaptureSquare;
104 ExtMove *endQuiets, *endBadCaptures = moves + MAX_MOVES - 1;
105 ExtMove moves[MAX_MOVES], *cur = moves, *endMoves = moves;
108 #endif // #ifndef MOVEPICK_H_INCLUDED