/*
Stockfish, a UCI chess playing engine derived from Glaurung 2.1
Copyright (C) 2004-2008 Tord Romstad (Glaurung author)
- Copyright (C) 2008-2010 Marco Costalba, Joona Kiiski, Tord Romstad
+ Copyright (C) 2008-2015 Marco Costalba, Joona Kiiski, Tord Romstad
+ Copyright (C) 2015-2016 Marco Costalba, Joona Kiiski, Gary Linscott, 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 "history.h"
+#include <algorithm> // For std::max
+#include <cstring> // For std::memset
+
+#include "movegen.h"
#include "position.h"
+#include "search.h"
#include "types.h"
-struct SearchStack;
-/// MovePicker is a class which is used to pick one legal move at a time from
-/// the current position. It is initialized with a Position object and a few
-/// moves we have reason to believe are good. The most important method is
-/// MovePicker::pick_next_move(), which returns a new legal move each time it
-/// is called, until there are no legal moves left, when MOVE_NONE is returned.
-/// In order to improve the efficiency of the alpha beta algorithm, MovePicker
-/// attempts to return the moves which are most likely to be strongest first.
+/// The Stats struct stores moves statistics. According to the template parameter
+/// the class can store History 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.
+/// 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<typename T, bool CM = false>
+struct Stats {
-class MovePicker {
+ static const Value Max = Value(1 << 28);
+
+ const T* operator[](Piece pc) const { return table[pc]; }
+ T* operator[](Piece pc) { return table[pc]; }
+ void clear() { std::memset(table, 0, sizeof(table)); }
+
+ void update(Piece pc, Square to, Move m) { table[pc][to] = m; }
+
+ void update(Piece pc, Square to, Value v) {
+
+ if (abs(int(v)) >= 324)
+ return;
+
+ table[pc][to] -= table[pc][to] * abs(int(v)) / (CM ? 936 : 324);
+ table[pc][to] += int(v) * 32;
+ }
+
+private:
+ T table[PIECE_NB][SQUARE_NB];
+};
+
+typedef Stats<Move> MoveStats;
+typedef Stats<Value, false> HistoryStats;
+typedef Stats<Value, true> CounterMoveStats;
+typedef Stats<CounterMoveStats> CounterMoveHistoryStats;
- MovePicker& operator=(const MovePicker&); // silence a warning under MSVC
+struct FromToStats {
+ Value get(Color c, Move m) const { return table[c][from_sq(m)][to_sq(m)]; }
+ void clear() { std::memset(table, 0, sizeof(table)); }
+
+ void update(Color c, Move m, Value v)
+ {
+ if (abs(int(v)) >= 324)
+ return;
+
+ Square f = from_sq(m);
+ Square t = to_sq(m);
+
+ table[c][f][t] -= table[c][f][t] * abs(int(v)) / 324;
+ table[c][f][t] += int(v) * 32;
+ }
+
+private:
+ Value table[COLOR_NB][SQUARE_NB][SQUARE_NB];
+};
+
+/// 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
+/// new pseudo legal move each time it is called, until there are no moves left,
+/// when MOVE_NONE is returned. In order to improve the efficiency of the alpha
+/// beta algorithm, MovePicker attempts to return the moves which are most likely
+/// to get a cut-off first.
+
+class MovePicker {
public:
- MovePicker(const Position& p, Move ttm, Depth d, const History& h, SearchStack* ss, Value beta);
- MovePicker(const Position& p, Move ttm, Depth d, const History& h);
- Move get_next_move();
+ MovePicker(const MovePicker&) = delete;
+ MovePicker& operator=(const MovePicker&) = delete;
+
+ MovePicker(const Position&, Move, Value);
+ MovePicker(const Position&, Move, Depth, Square);
+ MovePicker(const Position&, Move, Depth, Search::Stack*);
+
+ Move next_move();
private:
- void score_captures();
- void score_noncaptures();
- void score_evasions();
- void go_next_phase();
+ template<GenType> void score();
+ void generate_next_stage();
+ ExtMove* begin() { return moves; }
+ ExtMove* end() { return endMoves; }
const Position& pos;
- const History& H;
- Bitboard pinned;
- MoveStack ttMoves[2], killers[2];
- int badCaptureThreshold, phase;
- const uint8_t* phasePtr;
- MoveStack *curMove, *lastMove, *lastGoodNonCapture, *badCaptures;
- MoveStack moves[MOVES_MAX];
+ const Search::Stack* ss;
+ Move countermove;
+ Depth depth;
+ Move ttMove;
+ ExtMove killers[3];
+ Square recaptureSquare;
+ Value threshold;
+ int stage;
+ ExtMove* endBadCaptures = moves + MAX_MOVES - 1;
+ ExtMove moves[MAX_MOVES], *cur = moves, *endMoves = moves;
};
-#endif // !defined(MOVEPICK_H_INCLUDED)
+#endif // #ifndef MOVEPICK_H_INCLUDED