X-Git-Url: https://git.sesse.net/?p=stockfish;a=blobdiff_plain;f=src%2Fmovepick.h;h=33c4b08602bbd78ecdfd1a978ef287a43f713ec5;hp=21ea9ab3e2292afc1835059cbdfaf8ed74128892;hb=b8c00efa2767ebf74545d2ba4bd344ef7c963319;hpb=53ab32ef0b6e47d8d962f8c1fccd32d3c22f138c diff --git a/src/movepick.h b/src/movepick.h index 21ea9ab3..33c4b086 100644 --- a/src/movepick.h +++ b/src/movepick.h @@ -1,7 +1,8 @@ /* Stockfish, a UCI chess playing engine derived from Glaurung 2.1 Copyright (C) 2004-2008 Tord Romstad (Glaurung author) - Copyright (C) 2008-2014 Marco Costalba, Joona Kiiski, Tord Romstad + Copyright (C) 2008-2015 Marco Costalba, Joona Kiiski, Tord Romstad + Copyright (C) 2015-2020 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 @@ -20,56 +21,93 @@ #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, 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 -struct Stats { + T entry; - static const Value Max = Value(2000); - - const T* operator[](Piece p) const { return table[p]; } - void clear() { std::memset(table, 0, sizeof(table)); } +public: + void operator=(const T& v) { entry = v; } + T* operator&() { return &entry; } + T* operator->() { return &entry; } + operator const T&() const { return entry; } - void update(Piece p, Square to, Move m) { + void operator<<(int bonus) { + assert(abs(bonus) <= D); // Ensure range is [-D, D] + static_assert(D <= std::numeric_limits::max(), "D overflows T"); - if (m == table[p][to].first) - return; + entry += bonus - entry * abs(bonus) / D; - table[p][to].second = table[p][to].first; - table[p][to].first = m; + assert(abs(entry) <= D); } +}; - void update(Piece p, 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 (Gain) - table[p][to] = std::max(v, table[p][to] - 1); + void fill(const T& v) { - else if (abs(table[p][to] + v) < Max) - table[p][to] += v; - } + // For standard-layout 'this' points to first struct member + assert(std::is_standard_layout::value); -private: - T table[PIECE_NB][SQUARE_NB]; + typedef StatsEntry entry; + entry* p = reinterpret_cast(this); + std::fill(p, p + sizeof(*this) / sizeof(entry), v); + } }; -typedef Stats< true, Value> GainsStats; -typedef Stats HistoryStats; -typedef Stats > MovesStats; +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 }; + +/// 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; + +/// LowPlyHistory at higher depths records successful quiet moves on plies 0 to 3 +/// and quiet moves which are/were in the PV (ttPv) +/// It get cleared with each new search and get 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 @@ -78,33 +116,45 @@ typedef Stats > MovesStats; /// 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 { - MovePicker& operator=(const MovePicker&); // Silence a warning under MSVC + enum PickType { Next, Best }; public: - MovePicker(const Position&, Move, Depth, const HistoryStats&, Square); - MovePicker(const Position&, Move, const HistoryStats&, PieceType); - MovePicker(const Position&, Move, Depth, const HistoryStats&, Move*, Move*, Search::Stack*); - - template Move next_move(); + MovePicker(const MovePicker&) = delete; + MovePicker& operator=(const MovePicker&) = delete; + 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, + Move*, + int); + Move next_move(bool skipQuiets = false); private: + template Move select(Pred); template void score(); - void generate_next(); + ExtMove* begin() { return cur; } + ExtMove* end() { return endMoves; } const Position& pos; - const HistoryStats& history; - Search::Stack* ss; - Move* countermoves; - Move* followupmoves; - Depth depth; + const ButterflyHistory* mainHistory; + const LowPlyHistory* lowPlyHistory; + const CapturePieceToHistory* captureHistory; + const PieceToHistory** continuationHistory; Move ttMove; - ExtMove killers[6]; + ExtMove refutations[3], *cur, *endMoves, *endBadCaptures; + int stage; Square recaptureSquare; - int captureThreshold, stage; - ExtMove *cur, *end, *endQuiets, *endBadCaptures; + Value threshold; + Depth depth; + int ply; ExtMove moves[MAX_MOVES]; };