/*
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
#ifndef MOVEPICK_H_INCLUDED
#define MOVEPICK_H_INCLUDED
-#include <algorithm> // For std::max
-#include <cstring> // For std::memset
+#include <array>
#include "movegen.h"
#include "position.h"
-#include "search.h"
#include "types.h"
+/// StatBoards is a generic 2-dimensional array used to store various statistics
+template<int Size1, int Size2, typename T = int>
+struct StatBoards : public std::array<std::array<T, Size2>, Size1> {
-/// 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 {
+ void fill(const T& v) {
+ T* p = &(*this)[0][0];
+ std::fill(p, p + sizeof(*this) / sizeof(*p), v);
+ }
+};
- static const Value Max = Value(2000);
+/// ButterflyBoards are 2 tables (one for each color) indexed by the move's from
+/// and to squares, see chessprogramming.wikispaces.com/Butterfly+Boards
+typedef StatBoards<COLOR_NB, int(SQUARE_NB) * int(SQUARE_NB)> ButterflyBoards;
- const T* operator[](Piece p) const { return table[p]; }
- void clear() { std::memset(table, 0, sizeof(table)); }
+/// PieceToBoards are addressed by a move's [piece][to] information
+typedef StatBoards<PIECE_NB, SQUARE_NB> PieceToBoards;
- void update(Piece p, Square to, Move m) {
+/// ButterflyHistory records how often quiet moves have been successful or
+/// unsuccessful during the current search, and is used for reduction and move
+/// ordering decisions. It uses ButterflyBoards as backing store.
+struct ButterflyHistory : public ButterflyBoards {
- if (m == table[p][to].first)
- return;
+ void update(Color c, Move m, int v) {
- table[p][to].second = table[p][to].first;
- table[p][to].first = m;
- }
+ const int D = 324;
+ auto& entry = (*this)[c][from_to(m)];
- void update(Piece p, Square to, Value v) {
+ assert(abs(v) <= D); // Consistency check for below formula
- if (Gain)
- table[p][to] = std::max(v, table[p][to] - 1);
+ entry += v * 32 - entry * abs(v) / D;
- else if (abs(table[p][to] + v) < Max)
- table[p][to] += v;
+ assert(abs(entry) <= 32 * D);
}
+};
-private:
- T table[PIECE_NB][SQUARE_NB];
+/// PieceToHistory is like ButterflyHistory, but is based on PieceToBoards
+struct PieceToHistory : public PieceToBoards {
+
+ void update(Piece pc, Square to, int v) {
+
+ const int D = 936;
+ auto& entry = (*this)[pc][to];
+
+ assert(abs(v) <= D); // Consistency check for below formula
+
+ entry += v * 32 - entry * abs(v) / D;
+
+ assert(abs(entry) <= 32 * D);
+ }
};
-typedef Stats< true, Value> GainsStats;
-typedef Stats<false, Value> HistoryStats;
-typedef Stats<false, std::pair<Move, Move> > CountermovesStats;
+/// CounterMoveStat stores counter moves indexed by [piece][to] of the previous
+/// move, see chessprogramming.wikispaces.com/Countermove+Heuristic
+typedef StatBoards<PIECE_NB, SQUARE_NB, Move> CounterMoveStat;
+
+/// CounterMoveHistoryStat is like CounterMoveStat but instead of a move it
+/// stores a full history (based on PieceTo boards instead of ButterflyBoards).
+typedef StatBoards<PIECE_NB, SQUARE_NB, PieceToHistory> CounterMoveHistoryStat;
/// 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 {
-
- MovePicker& operator=(const MovePicker&); // Silence a warning under MSVC
-
public:
- MovePicker(const Position&, Move, Depth, const HistoryStats&, Square);
- MovePicker(const Position&, Move, const HistoryStats&, PieceType);
- MovePicker(const Position&, Move, Depth, const HistoryStats&, Move*, Search::Stack*);
+ 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*);
- 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 HistoryStats& history;
- Search::Stack* ss;
- Move* countermoves;
+ const Search::Stack* ss;
+ Move killers[2];
+ Move countermove;
Depth depth;
Move ttMove;
- ExtMove killers[4];
Square recaptureSquare;
- int captureThreshold, stage;
- ExtMove *cur, *end, *endQuiets, *endBadCaptures;
+ Value threshold;
+ int stage;
+ ExtMove *cur, *endMoves, *endBadCaptures;
ExtMove moves[MAX_MOVES];
};
projects / stockfish / blobdiff