#ifndef MOVEPICK_H_INCLUDED
#define MOVEPICK_H_INCLUDED
-#include <algorithm> // For std::max
-#include <cstring> // For std::memset
+#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> {
-/// HistoryStats records how often quiet moves have been successful or unsuccessful
-/// during the current search, and is used for reduction and move ordering decisions.
-struct HistoryStats {
-
- static const Value Max = Value(1 << 28);
+ void fill(const T& v) {
+ T* p = &(*this)[0][0];
+ std::fill(p, p + sizeof(*this) / sizeof(*p), v);
+ }
- Value get(Color c, Move m) const { return table[c][from_sq(m)][to_sq(m)]; }
- void clear() { std::memset(table, 0, sizeof(table)); }
- void update(Color c, Move m, Value v) {
+ void update(T& entry, int bonus, const int D) {
- Square from = from_sq(m);
- Square to = to_sq(m);
+ assert([&]{
+ int v = entry + bonus * 32 - entry * abs(bonus) / D;
+ return INT16_MIN < v && v < INT16_MAX;
+ }());
- const int denom = 324;
+ assert(abs(bonus) <= D); // Consistency check for below formula
- assert(abs(int(v)) <= denom); // Needed for stability.
+ entry += bonus * 32 - entry * abs(bonus) / D;
- table[c][from][to] -= table[c][from][to] * abs(int(v)) / denom;
- table[c][from][to] += int(v) * 32;
+ assert(abs(entry) <= 32 * D);
}
-
-private:
- Value table[COLOR_NB][SQUARE_NB][SQUARE_NB];
};
+/// 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;
-/// A template struct, used to generate MoveStats and CounterMoveHistoryStats:
-/// MoveStats store the move that refute a previous one.
-/// CounterMoveHistoryStats is like HistoryStats, but with two consecutive moves.
-/// 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<typename T>
-struct Stats {
- 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 fill(const Value& v) { std::fill(&table[0][0], &table[PIECE_NB-1][SQUARE_NB-1]+1, v); };
- void update(Piece pc, Square to, Move m) { table[pc][to] = m; }
- void update(Piece pc, Square to, Value v) {
-
- const int denom = 936;
+/// PieceToBoards are addressed by a move's [piece][to] information
+typedef StatBoards<PIECE_NB, SQUARE_NB> PieceToBoards;
- assert(abs(int(v)) <= denom); // Needed for stability.
+/// 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 {
- table[pc][to] -= table[pc][to] * abs(int(v)) / denom;
- table[pc][to] += int(v) * 32;
+ void update(Color c, Move m, int bonus) {
+ StatBoards::update((*this)[c][from_to(m)], bonus, 324);
}
+};
-private:
- T table[PIECE_NB][SQUARE_NB];
+/// 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);
+ }
};
-typedef Stats<Move> MoveStats;
-typedef Stats<Value> CounterMoveStats;
-typedef Stats<CounterMoveStats> CounterMoveHistoryStats;
+/// 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
/// 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.
-namespace Search { struct Stack; }
class MovePicker {
public:
MovePicker(const MovePicker&) = delete;
MovePicker& operator=(const MovePicker&) = delete;
-
MovePicker(const Position&, Move, Value);
- MovePicker(const Position&, Move, Depth, Square);
- MovePicker(const Position&, Move, Depth, Search::Stack*);
-
+ MovePicker(const Position&, Move, Depth, const ButterflyHistory*, const PieceToHistory**, Square);
+ MovePicker(const Position&, Move, Depth, const ButterflyHistory*, const PieceToHistory**, Move, Move*);
Move next_move(bool skipQuiets = false);
private:
ExtMove* end() { return endMoves; }
const Position& pos;
- const Search::Stack* ss;
- Move countermove;
- Depth depth;
- Move ttMove;
+ const ButterflyHistory* mainHistory;
+ const PieceToHistory** contHistory;
+ Move ttMove, countermove, killers[2];
+ ExtMove *cur, *endMoves, *endBadCaptures;
+ int stage;
Square recaptureSquare;
Value threshold;
- int stage;
- ExtMove *cur, *endMoves, *endBadCaptures;
+ Depth depth;
ExtMove moves[MAX_MOVES];
};
projects / stockfish / blobdiff