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
+ Copyright (C) 2015-2018 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 <limits>
+#include <type_traits>
#include "movegen.h"
#include "position.h"
#include "types.h"
+/// StatsEntry stores the stat table value. It is usually a number but could
+/// be a move or even a nested history. We use a class instead of naked value
+/// to directly call history update operator<<() on the entry so to use stats
+/// tables at caller sites as simple multi-dim arrays.
+template<typename T, int W, int D>
+class StatsEntry {
-/// 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 bool IsInt = std::is_integral<T>::value;
+ typedef typename std::conditional<IsInt, int, T>::type TT;
- static const Value Max = Value(1 << 28);
+ T entry;
- 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) {
+public:
+ T* get() { return &entry; }
+ void operator=(const T& v) { entry = v; }
+ operator TT() const { return entry; }
- Square from = from_sq(m);
- Square to = to_sq(m);
+ void operator<<(int bonus) {
- const int denom = 324;
+ assert(abs(bonus) <= D); // Ensure range is [-W * D, W * D]
+ assert(abs(W * D) < std::numeric_limits<T>::max()); // Ensure we don't overflow
- assert(abs(int(v)) <= denom); // Needed for stability.
+ entry += bonus * W - entry * abs(bonus) / D;
- table[c][from][to] -= table[c][from][to] * abs(int(v)) / denom;
- table[c][from][to] += int(v) * 32;
+ assert(abs(entry) <= W * D);
}
+};
-private:
- Value table[COLOR_NB][SQUARE_NB][SQUARE_NB];
+/// Stats is a generic N-dimensional array used to store various statistics.
+/// The first template T parameter is the base type of the array, the W parameter
+/// is the weight applied to the bonuses when we update values with the << operator,
+/// the D parameter limits the range of updates (range is [-W * D, W * D]), and
+/// the last parameters (Size and Sizes) encode the dimensions of the array.
+template <typename T, int W, int D, int Size, int... Sizes>
+struct Stats : public std::array<Stats<T, W, D, Sizes...>, Size>
+{
+ T* get() { return this->at(0).get(); }
+
+ void fill(const T& v) {
+ T* p = get();
+ std::fill(p, p + sizeof(*this) / sizeof(*p), v);
+ }
};
+template <typename T, int W, int D, int Size>
+struct Stats<T, W, D, Size> : public std::array<StatsEntry<T, W, D>, Size> {
+ T* get() { return this->at(0).get(); }
+};
-/// 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 fill(const Value& v) { std::fill(&table[0][0], &table[PIECE_NB-1][SQUARE_NB-1]+1, v); };
- void update(Piece pc, Square to, Move m) { table[pc][to] = m; }
- void update(Piece pc, Square to, Value v) {
+/// Different tables use different W/D parameter, name them to ease readibility
+enum StatsParams { W2 = 2, W32 = 32, D324 = 324, D936 = 936, NOT_USED = 0 };
- const int denom = 936;
+/// 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 2 tables (one for each color) indexed by
+/// the move's from and to squares, see chessprogramming.wikispaces.com/Butterfly+Boards
+typedef Stats<int16_t, W32, D324, COLOR_NB, int(SQUARE_NB) * int(SQUARE_NB)> ButterflyHistory;
- assert(abs(int(v)) <= denom); // Needed for stability.
+/// CounterMoveHistory stores counter moves indexed by [piece][to] of the previous
+/// move, see chessprogramming.wikispaces.com/Countermove+Heuristic
+typedef Stats<Move, NOT_USED, NOT_USED, PIECE_NB, SQUARE_NB> CounterMoveHistory;
- table[pc][to] -= table[pc][to] * abs(int(v)) / denom;
- table[pc][to] += int(v) * 32;
- }
+/// CapturePieceToHistory is addressed by a move's [piece][to][captured piece type]
+typedef Stats<int16_t, W2, D324, PIECE_NB, SQUARE_NB, PIECE_TYPE_NB> CapturePieceToHistory;
-private:
- T table[PIECE_NB][SQUARE_NB];
-};
+/// PieceToHistory is like ButterflyHistory but is addressed by a move's [piece][to]
+typedef Stats<int16_t, W32, D936, PIECE_NB, SQUARE_NB> PieceToHistory;
-typedef Stats<Move> MoveStats;
-typedef Stats<Value> CounterMoveStats;
-typedef Stats<CounterMoveStats> CounterMoveHistoryStats;
+/// ContinuationHistory is the combined history of a given pair of moves, usually
+/// the current one given a previous one. The nested history table is based on
+/// PieceToHistory instead of ButterflyBoards.
+typedef Stats<PieceToHistory, W32, NOT_USED, PIECE_NB, SQUARE_NB> ContinuationHistory;
/// 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, Value);
- MovePicker(const Position&, Move, Depth, Square);
- MovePicker(const Position&, Move, Depth, Search::Stack*);
-
+ MovePicker(const Position&, Move, Value, const CapturePieceToHistory*);
+ MovePicker(const Position&, Move, Depth, const ButterflyHistory*, const CapturePieceToHistory*, Square);
+ MovePicker(const Position&, Move, Depth, const ButterflyHistory*, const CapturePieceToHistory*, const PieceToHistory**, Move, Move*);
Move next_move(bool skipQuiets = false);
private:
ExtMove* end() { return endMoves; }
const Position& pos;
- const Search::Stack* ss;
- Move countermove;
- Depth depth;
- Move ttMove;
+ const ButterflyHistory* mainHistory;
+ const CapturePieceToHistory* captureHistory;
+ const PieceToHistory** contHistory;
+ Move ttMove, refutations[3];
+ ExtMove *cur, *endMoves, *endBadCaptures;
+ int stage;
Square recaptureSquare;
Value threshold;
- int stage;
- ExtMove *cur, *endMoves, *endBadCaptures;
+ Depth depth;
ExtMove moves[MAX_MOVES];
};
projects / stockfish / blobdiff