mirror of
https://github.com/peterosterlund2/droidfish.git
synced 2024-11-27 14:15:16 +01:00
119 lines
4.3 KiB
C++
119 lines
4.3 KiB
C++
/*
|
|
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
|
|
|
|
Stockfish is free software: you can redistribute it and/or modify
|
|
it under the terms of the GNU General Public License as published by
|
|
the Free Software Foundation, either version 3 of the License, or
|
|
(at your option) any later version.
|
|
|
|
Stockfish is distributed in the hope that it will be useful,
|
|
but WITHOUT ANY WARRANTY; without even the implied warranty of
|
|
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
|
|
GNU General Public License for more details.
|
|
|
|
You should have received a copy of the GNU General Public License
|
|
along with this program. If not, see <http://www.gnu.org/licenses/>.
|
|
*/
|
|
|
|
#ifndef MOVEPICK_H_INCLUDED
|
|
#define MOVEPICK_H_INCLUDED
|
|
|
|
#include <array>
|
|
|
|
#include "movegen.h"
|
|
#include "position.h"
|
|
#include "types.h"
|
|
|
|
/// StatBoards is a generic 2-dimensional array used to store various statistics
|
|
template<int Size1, int Size2, typename T = int16_t>
|
|
struct StatBoards : public std::array<std::array<T, Size2>, Size1> {
|
|
|
|
void fill(const T& v) {
|
|
T* p = &(*this)[0][0];
|
|
std::fill(p, p + sizeof(*this) / sizeof(*p), v);
|
|
}
|
|
|
|
void update(T& entry, int bonus, const int D) {
|
|
|
|
assert(abs(bonus) <= D); // Ensure range is [-32 * D, 32 * D]
|
|
assert(abs(32 * D) < INT16_MAX); // Ensure we don't overflow
|
|
|
|
entry += bonus * 32 - entry * abs(bonus) / D;
|
|
|
|
assert(abs(entry) <= 32 * D);
|
|
}
|
|
};
|
|
|
|
/// ButterflyBoards are 2 tables (one for each color) indexed by the move's from
|
|
/// and to squares, see chessprogramming.wikispaces.com/Butterfly+Boards
|
|
typedef StatBoards<COLOR_NB, int(SQUARE_NB) * int(SQUARE_NB)> ButterflyBoards;
|
|
|
|
/// PieceToBoards are addressed by a move's [piece][to] information
|
|
typedef StatBoards<PIECE_NB, SQUARE_NB> PieceToBoards;
|
|
|
|
/// 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 ButterflyBoards as backing store.
|
|
struct ButterflyHistory : public ButterflyBoards {
|
|
|
|
void update(Color c, Move m, int bonus) {
|
|
StatBoards::update((*this)[c][from_to(m)], bonus, 324);
|
|
}
|
|
};
|
|
|
|
/// PieceToHistory is like ButterflyHistory, but is based on PieceToBoards
|
|
struct PieceToHistory : public PieceToBoards {
|
|
|
|
void update(Piece pc, Square to, int bonus) {
|
|
StatBoards::update((*this)[pc][to], bonus, 936);
|
|
}
|
|
};
|
|
|
|
/// CounterMoveHistory stores counter moves indexed by [piece][to] of the previous
|
|
/// move, see chessprogramming.wikispaces.com/Countermove+Heuristic
|
|
typedef StatBoards<PIECE_NB, SQUARE_NB, Move> CounterMoveHistory;
|
|
|
|
/// ContinuationHistory is the history of a given pair of moves, usually the
|
|
/// current one given a previous one. History table is based on PieceToBoards
|
|
/// instead of ButterflyBoards.
|
|
typedef StatBoards<PIECE_NB, SQUARE_NB, PieceToHistory> 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 {
|
|
public:
|
|
MovePicker(const MovePicker&) = delete;
|
|
MovePicker& operator=(const MovePicker&) = delete;
|
|
MovePicker(const Position&, Move, Value);
|
|
MovePicker(const Position&, Move, Depth, const ButterflyHistory*, Square);
|
|
MovePicker(const Position&, Move, Depth, const ButterflyHistory*, const PieceToHistory**, Move, Move*);
|
|
Move next_move(bool skipQuiets = false);
|
|
|
|
private:
|
|
template<GenType> void score();
|
|
ExtMove* begin() { return cur; }
|
|
ExtMove* end() { return endMoves; }
|
|
|
|
const Position& pos;
|
|
const ButterflyHistory* mainHistory;
|
|
const PieceToHistory** contHistory;
|
|
Move ttMove, countermove, killers[2];
|
|
ExtMove *cur, *endMoves, *endBadCaptures;
|
|
int stage;
|
|
Square recaptureSquare;
|
|
Value threshold;
|
|
Depth depth;
|
|
ExtMove moves[MAX_MOVES];
|
|
};
|
|
|
|
#endif // #ifndef MOVEPICK_H_INCLUDED
|