Stockfish, a UCI chess playing engine derived from Glaurung 2.1
Copyright (C) 2004-2008 Tord Romstad (Glaurung author)
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
#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 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 {
+/// 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(250);
+ static const int Max = 1 << 28;
- const T* operator[](Piece pc) const { return table[pc]; }
- T* operator[](Piece pc) { return table[pc]; }
+ int 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, int v) {
+
+ Square from = from_sq(m);
+ Square to = to_sq(m);
- void update(Piece pc, Square to, Move m) {
+ const int D = 324;
- if (m == table[pc][to].first)
- return;
+ assert(abs(int(v)) <= D); // Consistency check for below formula
- table[pc][to].second = table[pc][to].first;
- table[pc][to].first = m;
+ table[c][from][to] -= table[c][from][to] * abs(int(v)) / D;
+ table[c][from][to] += int(v) * 32;
}
- void update(Piece pc, Square to, Value v) {
+private:
+ int table[COLOR_NB][SQUARE_NB][SQUARE_NB];
+};
+
+
+/// 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, int v) {
+
+ const int D = 936;
- if (Gain)
- table[pc][to] = std::max(v, table[pc][to] - 1);
+ assert(abs(int(v)) <= D); // Consistency check for below formula
- else if (abs(table[pc][to] + v) < Max)
- table[pc][to] += v;
+ table[pc][to] -= table[pc][to] * abs(int(v)) / D;
+ table[pc][to] += int(v) * 32;
}
private:
T table[PIECE_NB][SQUARE_NB];
};
-typedef Stats< true, Value> GainsStats;
-typedef Stats<false, Value> HistoryStats;
-typedef Stats<false, std::pair<Move, Move> > MovesStats;
-typedef Stats<false, HistoryStats> CounterMovesHistoryStats;
+typedef Stats<Move> MoveStats;
+typedef Stats<int> CounterMoveStats;
+typedef Stats<CounterMoveStats> CounterMoveHistoryStats;
/// MovePicker class is used to pick one pseudo legal move at a time from the
/// 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(const Position&, Move, Depth, const HistoryStats&, const CounterMovesHistoryStats&, Square);
- MovePicker(const Position&, Move, const HistoryStats&, const CounterMovesHistoryStats&, PieceType);
- MovePicker(const Position&, Move, Depth, const HistoryStats&, const CounterMovesHistoryStats&, Move*, Search::Stack*);
+ MovePicker(const Position&, Move, Value);
+ MovePicker(const Position&, Move, Depth, Square);
+ MovePicker(const Position&, Move, Depth, Search::Stack*);
- template<bool SpNode> Move next_move();
+ Move next_move(bool skipQuiets = false);
private:
template<GenType> void score();
- void generate_next_stage();
- ExtMove* begin() { return moves; }
+ ExtMove* begin() { return cur; }
ExtMove* end() { return endMoves; }
const Position& pos;
- const HistoryStats& history;
- const CounterMovesHistoryStats& counterMovesHistory;
- Search::Stack* ss;
- Move* countermoves;
+ const Search::Stack* ss;
+ Move killers[2];
+ Move countermove;
Depth depth;
Move ttMove;
- ExtMove killers[4];
Square recaptureSquare;
- Value captureThreshold;
+ Value threshold;
int stage;
- ExtMove *endQuiets, *endBadCaptures;
- ExtMove moves[MAX_MOVES], *cur = moves, *endMoves = moves;
+ ExtMove *cur, *endMoves, *endBadCaptures;
+ ExtMove moves[MAX_MOVES];
};
#endif // #ifndef MOVEPICK_H_INCLUDED