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.
39 template<typename T, bool CM = false>
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 if (abs(int(v)) >= 324)
59 table[pc][to] -= table[pc][to] * abs(int(v)) / (CM ? 512 : 324);
60 table[pc][to] += int(v) * (CM ? 64 : 32);
64 T table[PIECE_NB][SQUARE_NB];
67 typedef Stats<Move> MovesStats;
68 typedef Stats<Value, false> HistoryStats;
69 typedef Stats<Value, true> CounterMovesStats;
70 typedef Stats<CounterMovesStats> CounterMovesHistoryStats;
73 /// MovePicker class is used to pick one pseudo legal move at a time from the
74 /// current position. The most important method is next_move(), which returns a
75 /// new pseudo legal move each time it is called, until there are no moves left,
76 /// when MOVE_NONE is returned. In order to improve the efficiency of the alpha
77 /// beta algorithm, MovePicker attempts to return the moves which are most likely
78 /// to get a cut-off first.
82 MovePicker(const MovePicker&) = delete;
83 MovePicker& operator=(const MovePicker&) = delete;
85 MovePicker(const Position&, Move, Depth, const HistoryStats&, Square);
86 MovePicker(const Position&, Move, const HistoryStats&, Value);
87 MovePicker(const Position&, Move, Depth, const HistoryStats&, const CounterMovesStats&, Move, Search::Stack*);
92 template<GenType> void score();
93 void generate_next_stage();
94 ExtMove* begin() { return moves; }
95 ExtMove* end() { return endMoves; }
98 const HistoryStats& history;
99 const CounterMovesStats* counterMovesHistory;
105 Square recaptureSquare;
108 ExtMove *endQuiets, *endBadCaptures = moves + MAX_MOVES - 1;
109 ExtMove moves[MAX_MOVES], *cur = moves, *endMoves = moves;
112 #endif // #ifndef MOVEPICK_H_INCLUDED