/*
Stockfish, a UCI chess playing engine derived from Glaurung 2.1
- Copyright (C) 2004-2022 The Stockfish developers (see AUTHORS file)
+ Copyright (C) 2004-2023 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
#define MOVEPICK_H_INCLUDED
#include <array>
+#include <cassert>
+#include <cstdint>
+#include <cstdlib>
#include <limits>
-#include <type_traits>
+#include <type_traits> // IWYU pragma: keep
#include "movegen.h"
-#include "position.h"
#include "types.h"
namespace Stockfish {
+class Position;
-/// 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.
+// 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 a 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 D>
class StatsEntry {
assert(abs(bonus) <= D); // Ensure range is [-D, D]
static_assert(D <= std::numeric_limits<T>::max(), "D overflows T");
- entry += bonus - entry * abs(bonus) / D;
+ entry += (bonus * D - entry * abs(bonus)) / (D * 5 / 4);
assert(abs(entry) <= D);
}
};
-/// 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.
+// Stats is a generic N-dimensional array used to store various statistics.
+// The first template parameter T is the base type of the array, and 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 <typename T, int D, int Size, int... Sizes>
struct Stats : public std::array<Stats<T, D, Sizes...>, Size>
{
- typedef Stats<T, D, Size, Sizes...> stats;
+ using stats = Stats<T, D, Size, Sizes...>;
void fill(const T& v) {
- // For standard-layout 'this' points to first struct member
- assert(std::is_standard_layout<stats>::value);
+ // For standard-layout 'this' points to the first struct member
+ assert(std::is_standard_layout_v<stats>);
- typedef StatsEntry<T, D> entry;
+ using entry = StatsEntry<T, D>;
entry* p = reinterpret_cast<entry*>(this);
std::fill(p, p + sizeof(*this) / sizeof(entry), v);
}
template <typename T, int D, int Size>
struct Stats<T, D, Size> : public std::array<StatsEntry<T, D>, Size> {};
-/// In stats table, D=0 means that the template parameter is not used
+// 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<int16_t, 14365, COLOR_NB, int(SQUARE_NB) * int(SQUARE_NB)> ButterflyHistory;
+// 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
+// (~11 elo)
+using ButterflyHistory = Stats<int16_t, 7183, COLOR_NB, int(SQUARE_NB) * int(SQUARE_NB)>;
-/// CounterMoveHistory stores counter moves indexed by [piece][to] of the previous
-/// move, see www.chessprogramming.org/Countermove_Heuristic
-typedef Stats<Move, NOT_USED, PIECE_NB, SQUARE_NB> CounterMoveHistory;
+// CounterMoveHistory stores counter moves indexed by [piece][to] of the previous
+// move, see www.chessprogramming.org/Countermove_Heuristic
+using CounterMoveHistory = Stats<Move, NOT_USED, PIECE_NB, SQUARE_NB>;
-/// CapturePieceToHistory is addressed by a move's [piece][to][captured piece type]
-typedef Stats<int16_t, 10692, PIECE_NB, SQUARE_NB, PIECE_TYPE_NB> CapturePieceToHistory;
+// CapturePieceToHistory is addressed by a move's [piece][to][captured piece type]
+using CapturePieceToHistory = Stats<int16_t, 10692, PIECE_NB, SQUARE_NB, PIECE_TYPE_NB>;
-/// PieceToHistory is like ButterflyHistory but is addressed by a move's [piece][to]
-typedef Stats<int16_t, 29952, PIECE_NB, SQUARE_NB> PieceToHistory;
+// PieceToHistory is like ButterflyHistory but is addressed by a move's [piece][to]
+using PieceToHistory = Stats<int16_t, 29952, PIECE_NB, SQUARE_NB>;
-/// 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, NOT_USED, PIECE_NB, SQUARE_NB> ContinuationHistory;
+// 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.
+// (~63 elo)
+using ContinuationHistory = Stats<PieceToHistory, NOT_USED, PIECE_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
-/// 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.
+// 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 };
const CapturePieceToHistory*,
const PieceToHistory**,
Square);
- MovePicker(const Position&, Move, Value, Depth, const CapturePieceToHistory*);
+ MovePicker(const Position&, Move, Value, const CapturePieceToHistory*);
Move next_move(bool skipQuiets = false);
private:
projects / stockfish / blobdiff