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BadFish/src/movepick.h
Stefan Geschwentner 53ab32ef0b Introduce 'follow up' moves
When we have a fail-high of a quiet move, store it in
a Followupmoves table indexed by the previous move of
the same color (instead of immediate previous move as
is in countermoves case).

Then use this table for quiet moves ordering in the same
way we are already doing with countermoves.

These followup moves will be tried just after countermoves
and before remaining quiet moves.

Passed both short TC
LLR: 2.95 (-2.94,2.94) [-1.50,4.50]
Total: 10350 W: 1998 L: 1866 D: 6486

And long TC
LLR: 2.95 (-2.94,2.94) [0.00,6.00]
Total: 14066 W: 2303 L: 2137 D: 9626

bench: 7205153
2014-01-14 09:24:35 +01:00

111 lines
3.6 KiB
C++

/*
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
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 <algorithm> // For std::max
#include <cstring> // For std::memset
#include "movegen.h"
#include "position.h"
#include "search.h"
#include "types.h"
/// 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<bool Gain, typename T>
struct Stats {
static const Value Max = Value(2000);
const T* operator[](Piece p) const { return table[p]; }
void clear() { std::memset(table, 0, sizeof(table)); }
void update(Piece p, Square to, Move m) {
if (m == table[p][to].first)
return;
table[p][to].second = table[p][to].first;
table[p][to].first = m;
}
void update(Piece p, Square to, Value v) {
if (Gain)
table[p][to] = std::max(v, table[p][to] - 1);
else if (abs(table[p][to] + v) < Max)
table[p][to] += v;
}
private:
T table[PIECE_NB][SQUARE_NB];
};
typedef Stats< true, Value> GainsStats;
typedef Stats<false, Value> HistoryStats;
typedef Stats<false, std::pair<Move, Move> > MovesStats;
/// 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 {
MovePicker& operator=(const MovePicker&); // Silence a warning under MSVC
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<bool SpNode> Move next_move();
private:
template<GenType> void score();
void generate_next();
const Position& pos;
const HistoryStats& history;
Search::Stack* ss;
Move* countermoves;
Move* followupmoves;
Depth depth;
Move ttMove;
ExtMove killers[6];
Square recaptureSquare;
int captureThreshold, stage;
ExtMove *cur, *end, *endQuiets, *endBadCaptures;
ExtMove moves[MAX_MOVES];
};
#endif // #ifndef MOVEPICK_H_INCLUDED