/*
Stockfish, a UCI chess playing engine derived from Glaurung 2.1
Copyright (C) 2004-2008 Tord Romstad (Glaurung author)
- Copyright (C) 2008-2013 Marco Costalba, Joona Kiiski, Tord Romstad
+ Copyright (C) 2008-2015 Marco Costalba, Joona Kiiski, Tord Romstad
+ Copyright (C) 2015-2017 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 <algorithm> // For std::max
-#include <cstring> // For memset
+#include <cstring> // For std::memset
#include "movegen.h"
#include "position.h"
-#include "search.h"
#include "types.h"
-/// The Stats struct stores moves statistics. According to the template parameter
-/// the class can store both History and Gains type statistics. 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. 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.
-template<bool Gain>
-struct Stats {
+/// HistoryStats records how often quiet moves have been successful or unsuccessful
+/// during the current search, and is used for reduction and move ordering decisions.
+struct HistoryStats {
+
+ static const Value Max = Value(1 << 28);
- static const Value Max = Value(2000);
+ 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) {
- const Value* operator[](Piece p) const { return &table[p][0]; }
- void clear() { memset(table, 0, sizeof(table)); }
+ Square from = from_sq(m);
+ Square to = to_sq(m);
- void update(Piece p, Square to, Value v) {
+ const int denom = 324;
- if (Gain)
- table[p][to] = std::max(v, table[p][to] - 1);
+ assert(abs(int(v)) <= denom); // Needed for stability.
- else if (abs(table[p][to] + v) < Max)
- table[p][to] += v;
+ table[c][from][to] -= table[c][from][to] * abs(int(v)) / denom;
+ table[c][from][to] += int(v) * 32;
}
private:
- Value table[PIECE_NB][SQUARE_NB];
+ Value table[COLOR_NB][SQUARE_NB][SQUARE_NB];
};
-typedef Stats<false> History;
-typedef Stats<true> Gains;
-// FIXME: Document me
-struct RefutationTable {
+/// A template struct, used to generate MoveStats and CounterMoveHistoryStats:
+/// MoveStats store the move that refute a previous one.
+/// CounterMoveHistoryStats is like HistoryStats, but with two consecutive moves.
+/// 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>
+struct Stats {
+ 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) {
+
+ const int denom = 936;
- void clear() { memset(table, 0, sizeof(table)); }
- void update(Piece p, Square to, Move m) { table[p][to] = m; }
- Move get(Piece p, Square to) const { return table[p][to]; }
+ assert(abs(int(v)) <= denom); // Needed for stability.
-private:
- Move table[PIECE_NB][SQUARE_NB]; // Mapping: "move A" -> "move B which refutes move A"
+ table[pc][to] -= table[pc][to] * abs(int(v)) / denom;
+ table[pc][to] += int(v) * 32;
+ }
+private:
+ T table[PIECE_NB][SQUARE_NB];
};
+typedef Stats<Move> MoveStats;
+typedef Stats<Value> CounterMoveStats;
+typedef Stats<CounterMoveStats> CounterMoveHistoryStats;
+
+
/// 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.
+namespace Search { struct Stack; }
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, Value);
+ MovePicker(const Position&, Move, Depth, Square);
+ MovePicker(const Position&, Move, Depth, Search::Stack*);
-public:
- MovePicker(const Position&, Move, Depth, const History&, Search::Stack*, Move, Value);
- MovePicker(const Position&, Move, Depth, const History&, Square);
- MovePicker(const Position&, Move, const History&, PieceType);
- template<bool SpNode> Move next_move();
+ Move next_move(bool skipQuiets = false);
private:
template<GenType> void score();
- void generate_next();
+ ExtMove* begin() { return cur; }
+ ExtMove* end() { return endMoves; }
const Position& pos;
- const History& Hist;
- Search::Stack* ss;
+ const Search::Stack* ss;
+ Move countermove;
Depth depth;
Move ttMove;
- MoveStack killers[3];
Square recaptureSquare;
- int captureThreshold, phase;
- MoveStack *cur, *end, *endQuiets, *endBadCaptures;
- MoveStack moves[MAX_MOVES];
+ Value threshold;
+ int stage;
+ ExtMove *cur, *endMoves, *endBadCaptures;
+ ExtMove moves[MAX_MOVES];
};
-#endif // !defined(MOVEPICK_H_INCLUDED)
+#endif // #ifndef MOVEPICK_H_INCLUDED