/*
Stockfish, a UCI chess playing engine derived from Glaurung 2.1
Copyright (C) 2004-2008 Tord Romstad (Glaurung author)
- Copyright (C) 2008-2012 Marco Costalba, Joona Kiiski, Tord Romstad
+ Copyright (C) 2008-2015 Marco Costalba, Joona Kiiski, Tord Romstad
Stockfish is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
-#if !defined MOVEPICK_H_INCLUDED
+#ifndef MOVEPICK_H_INCLUDED
#define MOVEPICK_H_INCLUDED
+#include <algorithm> // For std::max
+#include <cstring> // For std::memset
+
+#include "movegen.h"
#include "position.h"
#include "search.h"
#include "types.h"
-/// The History class stores statistics about how often different moves
-/// have been successful or unsuccessful during the current search. These
-/// statistics are used for reduction and move ordering decisions. History
-/// entries are stored according only to moving piece and destination square,
-/// in particular two moves with different origin but same destination and
-/// same piece will be considered identical.
+/// The Stats struct stores moves statistics. According to the template parameter
+/// the class can store History, Gains and Countermoves. History records how often
+/// different moves have been successful or unsuccessful during the current search
+/// and is used for reduction and move ordering decisions. Gains records the move's
+/// best evaluation gain from one ply to the next and is used for pruning decisions.
+/// Countermoves store the move that refute a previous one. Entries are stored
+/// using only the moving piece and destination square, hence two moves with
+/// different origin but same destination and piece will be considered identical.
+template<bool Gain, typename T>
+struct Stats {
-class History {
-public:
+ static const Value Max = Value(250);
+
+ const T* operator[](Piece pc) const { return table[pc]; }
+ void clear() { std::memset(table, 0, sizeof(table)); }
+
+ void update(Piece pc, Square to, Move m) {
+
+ if (m == table[pc][to].first)
+ return;
- static const Value Max = Value(2000);
+ table[pc][to].second = table[pc][to].first;
+ table[pc][to].first = m;
+ }
- const Value* operator[](Piece p) const { return &history[p][0]; }
- Value gain(Piece p, Square to) const { return gains[p][to]; }
+ void update(Piece pc, Square to, Value v) {
- void clear();
- void update(Piece p, Square to, Value bonus);
- void update_gain(Piece p, Square to, Value gain);
+ if (Gain)
+ table[pc][to] = std::max(v, table[pc][to] - 1);
+
+ else if (abs(table[pc][to] + v) < Max)
+ table[pc][to] += v;
+ }
private:
- Value history[PIECE_NB][SQUARE_NB];
- Value gains[PIECE_NB][SQUARE_NB];
+ T table[PIECE_NB][SQUARE_NB];
};
+typedef Stats< true, Value> GainsStats;
+typedef Stats<false, Value> HistoryStats;
+typedef Stats<false, std::pair<Move, Move> > MovesStats;
+
/// MovePicker class is used to pick one pseudo legal move at a time from the
/// current position. The most important method is next_move(), which returns a
/// to get a cut-off first.
class MovePicker {
+public:
+ MovePicker(const MovePicker&) = delete;
+ MovePicker& operator=(const MovePicker&) = delete;
- MovePicker& operator=(const MovePicker&); // Silence a warning under MSVC
+ MovePicker(const Position&, Move, Depth, const HistoryStats&, Square);
+ MovePicker(const Position&, Move, const HistoryStats&, PieceType);
+ MovePicker(const Position&, Move, Depth, const HistoryStats&, Move*, Move*, Search::Stack*);
-public:
- MovePicker(const Position&, Move, Depth, const History&, Search::Stack*, Value);
- MovePicker(const Position&, Move, Depth, const History&, Square);
- MovePicker(const Position&, Move, const History&, PieceType);
template<bool SpNode> Move next_move();
private:
- void score_captures();
- void score_noncaptures();
- void score_evasions();
- void generate_next();
+ template<GenType> void score();
+ void generate_next_stage();
+ ExtMove* begin() { return moves; }
+ ExtMove* end() { return endMoves; }
const Position& pos;
- const History& H;
+ const HistoryStats& history;
Search::Stack* ss;
+ Move* countermoves;
+ Move* followupmoves;
Depth depth;
Move ttMove;
- MoveStack killers[2];
+ ExtMove killers[6];
Square recaptureSquare;
- int captureThreshold, phase;
- MoveStack *cur, *end, *endQuiets, *endBadCaptures;
- MoveStack moves[MAX_MOVES];
+ Value captureThreshold;
+ int stage;
+ ExtMove *endQuiets, *endBadCaptures;
+ ExtMove moves[MAX_MOVES], *cur = moves, *endMoves = moves;
};
-#endif // !defined(MOVEPICK_H_INCLUDED)
+#endif // #ifndef MOVEPICK_H_INCLUDED