X-Git-Url: https://git.sesse.net/?p=stockfish;a=blobdiff_plain;f=src%2Fmovepick.h;h=ea599cda1afbe10a04f8a2f9f77ffc4becc237b8;hp=5896bbefab9e9d0c3876fc44942d41cc8c393d4e;hb=7d0a16e06d968c81f17140b0123db9768ce02a82;hpb=b2edac7075ca238326378cb2c5ef09f7cdb2fd9e diff --git a/src/movepick.h b/src/movepick.h index 5896bbef..ea599cda 100644 --- a/src/movepick.h +++ b/src/movepick.h @@ -1,7 +1,6 @@ /* 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) 2004-2021 The Stockfish developers (see AUTHORS file) Stockfish is free software: you can redistribute it and/or modify it under the terms of the GNU General Public License as published by @@ -20,89 +19,141 @@ #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(250); +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) { + entry += bonus - entry * abs(bonus) / D; - if (m != table[pc][to]) - table[pc][to] = m; + assert(abs(entry) <= D); } +}; - void update(Piece pc, Square to, Value v) { +/// 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; - if (abs(table[pc][to] + v) < Max) - table[pc][to] += v; - } + 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 HistoryStats; -typedef Stats MovesStats; -typedef Stats CounterMovesHistoryStats; +template +struct Stats : public std::array, Size> {}; +/// In stats table, D=0 means that the template parameter is not used +enum StatsParams { NOT_USED = 0 }; +enum StatsType { NoCaptures, Captures }; -/// 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. +/// 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; + +/// At higher depths LowPlyHistory records successful quiet moves near the root +/// and quiet moves which are/were in the PV (ttPv). It is cleared with each new +/// search and filled during iterative deepening. +constexpr int MAX_LPH = 4; +typedef Stats LowPlyHistory; + +/// CounterMoveHistory stores counter moves indexed by [piece][to] of the previous +/// move, see www.chessprogramming.org/Countermove_Heuristic +typedef Stats CounterMoveHistory; + +/// CapturePieceToHistory is addressed by a move's [piece][to][captured piece type] +typedef Stats CapturePieceToHistory; + +/// 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; + + +/// 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. class MovePicker { + + enum PickType { Next, Best }; + 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*); - - template Move next_move(); + 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 LowPlyHistory*, + const CapturePieceToHistory*, + const PieceToHistory**, + Move, + const Move*, + int); + 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 HistoryStats& history; - const CounterMovesHistoryStats& counterMovesHistory; - Search::Stack* ss; - Move countermove; - Depth depth; + const ButterflyHistory* mainHistory; + const LowPlyHistory* lowPlyHistory; + const CapturePieceToHistory* captureHistory; + const PieceToHistory** continuationHistory; Move ttMove; - ExtMove killers[3]; - Square recaptureSquare; - Value captureThreshold; + ExtMove refutations[3], *cur, *endMoves, *endBadCaptures; int stage; - ExtMove *endQuiets, *endBadCaptures; - ExtMove moves[MAX_MOVES], *cur = moves, *endMoves = moves; + Square recaptureSquare; + Value threshold; + Depth depth; + int ply; + ExtMove moves[MAX_MOVES]; }; #endif // #ifndef MOVEPICK_H_INCLUDED