X-Git-Url: https://git.sesse.net/?p=stockfish;a=blobdiff_plain;f=src%2Fmovepick.h;h=105c95d7d13f06e47efe048d5a13f4f2b58e1866;hp=e69255e604b117f38e1900b397fff43ec159e398;hb=44f79bdf5a092c3acec0a8bf8f2c1440e5a9da90;hpb=602d7fbb07e2cb1643469c0116fa47d711398a06 diff --git a/src/movepick.h b/src/movepick.h index e69255e6..105c95d7 100644 --- a/src/movepick.h +++ b/src/movepick.h @@ -2,7 +2,7 @@ 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) 2015-2016 Marco Costalba, Joona Kiiski, Gary Linscott, Tord Romstad + Copyright (C) 2015-2019 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 @@ -21,71 +21,88 @@ #ifndef MOVEPICK_H_INCLUDED #define MOVEPICK_H_INCLUDED -#include // For std::max -#include // For std::memset +#include +#include +#include #include "movegen.h" #include "position.h" -#include "search.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 +class StatsEntry { -/// 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 -struct Stats { + T entry; - static const Value Max = Value(1 << 28); +public: + void operator=(const T& v) { entry = v; } + T* operator&() { return &entry; } + T* operator->() { return &entry; } + operator const T&() const { return entry; } - 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 operator<<(int bonus) { + assert(abs(bonus) <= D); // Ensure range is [-D, D] + static_assert(D <= std::numeric_limits::max(), "D overflows T"); - void update(Piece pc, Square to, Move m) { table[pc][to] = m; } + entry += bonus - entry * abs(bonus) / D; - void update(Piece pc, Square to, Value v) { + assert(abs(entry) <= D); + } +}; - if (abs(int(v)) >= 324) - return; +/// Stats is a generic N-dimensional array used to store various statistics. +/// The first template parameter T is the base type of the array, the second +/// template parameter D limits the range of updates in [-D, D] when we update +/// values with the << operator, while the last parameters (Size and Sizes) +/// encode the dimensions of the array. +template +struct Stats : public std::array, Size> +{ + typedef Stats stats; - table[pc][to] -= table[pc][to] * abs(int(v)) / (CM ? 936 : 324); - table[pc][to] += int(v) * 32; - } + void fill(const T& v) { -private: - T table[PIECE_NB][SQUARE_NB]; + // For standard-layout 'this' points to first struct member + assert(std::is_standard_layout::value); + + typedef StatsEntry entry; + entry* p = reinterpret_cast(this); + std::fill(p, p + sizeof(*this) / sizeof(entry), v); + } }; -typedef Stats MoveStats; -typedef Stats HistoryStats; -typedef Stats CounterMoveStats; -typedef Stats CounterMoveHistoryStats; +template +struct Stats : public std::array, Size> {}; -struct FromToStats { +/// In stats table, D=0 means that the template parameter is not used +enum StatsParams { NOT_USED = 0 }; +enum StatsType { NoCaptures, Captures }; - Value get(Color c, Move m) const { return table[c][from_sq(m)][to_sq(m)]; } - void clear() { std::memset(table, 0, sizeof(table)); } +/// 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 www.chessprogramming.org/Butterfly_Boards +typedef Stats ButterflyHistory; - void update(Color c, Move m, Value v) - { - if (abs(int(v)) >= 324) - return; +/// CounterMoveHistory stores counter moves indexed by [piece][to] of the previous +/// move, see www.chessprogramming.org/Countermove_Heuristic +typedef Stats CounterMoveHistory; - Square f = from_sq(m); - Square t = to_sq(m); +/// CapturePieceToHistory is addressed by a move's [piece][to][captured piece type] +typedef Stats CapturePieceToHistory; - table[c][f][t] -= table[c][f][t] * abs(int(v)) / 324; - table[c][f][t] += int(v) * 32; - } +/// PieceToHistory is like ButterflyHistory but is addressed by a move's [piece][to] +typedef Stats PieceToHistory; + +/// 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 ContinuationHistory; -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 @@ -93,36 +110,42 @@ private: /// 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 { + + enum PickType { Next, Best }; + 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*); - - Move next_move(); - int see_sign() const; + MovePicker(const Position&, Move, Value, const CapturePieceToHistory*); + MovePicker(const Position&, Move, Depth, const ButterflyHistory*, + const CapturePieceToHistory*, + const PieceToHistory**, + Square); + MovePicker(const Position&, Move, Depth, const ButterflyHistory*, + const CapturePieceToHistory*, + const PieceToHistory**, + Move, + Move*); + Move next_move(bool skipQuiets = false); private: + template Move select(Pred); template void score(); - void generate_next_stage(); - ExtMove* begin() { return moves; } + ExtMove* begin() { return cur; } ExtMove* end() { return endMoves; } const Position& pos; - const Search::Stack* ss; - Move countermove; - Depth depth; + const ButterflyHistory* mainHistory; + const CapturePieceToHistory* captureHistory; + const PieceToHistory** continuationHistory; Move ttMove; - ExtMove killers[3]; + ExtMove refutations[3], *cur, *endMoves, *endBadCaptures; + int stage; Square recaptureSquare; Value threshold; - int stage; - ExtMove* endBadCaptures = moves + MAX_MOVES - 1; - ExtMove moves[MAX_MOVES], *cur = moves, *endMoves = moves; + Depth depth; + ExtMove moves[MAX_MOVES]; }; #endif // #ifndef MOVEPICK_H_INCLUDED