/*
Stockfish, a UCI chess playing engine derived from Glaurung 2.1
Copyright (C) 2004-2008 Tord Romstad (Glaurung author)
- Copyright (C) 2008-2012 Marco Costalba, Joona Kiiski, Tord Romstad
+ Copyright (C) 2008-2013 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
along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
-#if !defined(POSITION_H_INCLUDED)
+#ifndef POSITION_H_INCLUDED
#define POSITION_H_INCLUDED
#include <cassert>
+#include <cstddef>
#include "bitboard.h"
#include "types.h"
/// The checkInfo struct is initialized at c'tor time and keeps info used
/// to detect if a move gives check.
class Position;
-class Thread;
+struct Thread;
struct CheckInfo {
Bitboard dcCandidates;
Bitboard pinned;
- Bitboard checkSq[8];
+ Bitboard checkSq[PIECE_TYPE_NB];
Square ksq;
};
-/// The StateInfo struct stores information we need to restore a Position
+/// The StateInfo struct stores information needed to restore a Position
/// object to its previous state when we retract a move. Whenever a move
-/// is made on the board (by calling Position::do_move), an StateInfo object
-/// must be passed as a parameter.
+/// is made on the board (by calling Position::do_move), a StateInfo
+/// object must be passed as a parameter.
struct StateInfo {
Key pawnKey, materialKey;
- Value npMaterial[2];
+ Value npMaterial[COLOR_NB];
int castleRights, rule50, pliesFromNull;
- Score psqScore;
+ Score psq;
Square epSquare;
Key key;
StateInfo* previous;
};
-struct ReducedStateInfo {
- Key pawnKey, materialKey;
- Value npMaterial[2];
- int castleRights, rule50, pliesFromNull;
- Score psqScore;
- Square epSquare;
-};
+/// When making a move the current StateInfo up to 'key' excluded is copied to
+/// the new one. Here we calculate the quad words (64bits) needed to be copied.
+const size_t StateCopySize64 = offsetof(StateInfo, key) / sizeof(uint64_t) + 1;
-/// The position data structure. A position consists of the following data:
-///
-/// * For each piece type, a bitboard representing the squares occupied
-/// by pieces of that type.
-/// * For each color, a bitboard representing the squares occupied by
-/// pieces of that color.
-/// * A bitboard of all occupied squares.
-/// * A bitboard of all checking pieces.
-/// * A 64-entry array of pieces, indexed by the squares of the board.
-/// * The current side to move.
-/// * Information about the castling rights for both sides.
-/// * The initial files of the kings and both pairs of rooks. This is
-/// used to implement the Chess960 castling rules.
-/// * The en passant square (which is SQ_NONE if no en passant capture is
-/// possible).
-/// * The squares of the kings for both sides.
-/// * Hash keys for the position itself, the current pawn structure, and
-/// the current material situation.
-/// * Hash keys for all previous positions in the game for detecting
-/// repetition draws.
-/// * A counter for detecting 50 move rule draws.
+
+/// The Position class stores the information regarding the board representation
+/// like pieces, side to move, hash keys, castling info, etc. The most important
+/// methods are do_move() and undo_move(), used by the search to update node info
+/// when traversing the search tree.
class Position {
public:
Position() {}
- Position(const Position& p) { *this = p; }
Position(const Position& p, Thread* t) { *this = p; thisThread = t; }
- Position(const std::string& f, bool c960, Thread* t) { from_fen(f, c960, t); }
- void operator=(const Position&);
+ Position(const std::string& f, bool c960, Thread* t) { set(f, c960, t); }
+ Position& operator=(const Position&);
+ static void init();
// Text input/output
- void from_fen(const std::string& fen, bool isChess960, Thread* th);
- const std::string to_fen() const;
- void print(Move m = MOVE_NONE) const;
+ void set(const std::string& fen, bool isChess960, Thread* th);
+ const std::string fen() const;
+ const std::string pretty(Move m = MOVE_NONE) const;
// Position representation
Bitboard pieces() const;
Piece piece_on(Square s) const;
Square king_square(Color c) const;
Square ep_square() const;
- bool is_empty(Square s) const;
- const Square* piece_list(Color c, PieceType pt) const;
- int piece_count(Color c, PieceType pt) const;
+ bool empty(Square s) const;
+ template<PieceType Pt> int count(Color c) const;
+ template<PieceType Pt> const Square* list(Color c) const;
// Castling
int can_castle(CastleRight f) const;
Square castle_rook_square(Color c, CastlingSide s) const;
// Checking
- bool in_check() const;
Bitboard checkers() const;
Bitboard discovered_check_candidates() const;
- Bitboard pinned_pieces() const;
+ Bitboard pinned_pieces(Color toMove) const;
// Attacks to/from a given square
Bitboard attackers_to(Square s) const;
template<PieceType> Bitboard attacks_from(Square s, Color c) const;
// Properties of moves
- bool move_gives_check(Move m, const CheckInfo& ci) const;
- bool move_attacks_square(Move m, Square s) const;
- bool move_is_legal(const Move m) const;
- bool pl_move_is_legal(Move m, Bitboard pinned) const;
- bool is_pseudo_legal(const Move m) const;
- bool is_capture(Move m) const;
- bool is_capture_or_promotion(Move m) const;
- bool is_passed_pawn_push(Move m) const;
- Piece piece_moved(Move m) const;
+ bool legal(Move m, Bitboard pinned) const;
+ bool pseudo_legal(const Move m) const;
+ bool capture(Move m) const;
+ bool capture_or_promotion(Move m) const;
+ bool gives_check(Move m, const CheckInfo& ci) const;
+ bool passed_pawn_push(Move m) const;
+ Piece moved_piece(Move m) const;
PieceType captured_piece_type() const;
// Piece specific
- bool pawn_is_passed(Color c, Square s) const;
+ bool pawn_passed(Color c, Square s) const;
bool pawn_on_7th(Color c) const;
- bool opposite_bishops() const;
bool bishop_pair(Color c) const;
+ bool opposite_bishops() const;
// Doing and undoing moves
void do_move(Move m, StateInfo& st);
void do_move(Move m, StateInfo& st, const CheckInfo& ci, bool moveIsCheck);
void undo_move(Move m);
- template<bool Do> void do_null_move(StateInfo& st);
+ void do_null_move(StateInfo& st);
+ void undo_null_move();
// Static exchange evaluation
- int see(Move m) const;
+ int see(Move m, int asymmThreshold = 0) const;
int see_sign(Move m) const;
// Accessing hash keys
// Incremental piece-square evaluation
Score psq_score() const;
- Score psq_delta(Piece p, Square from, Square to) const;
Value non_pawn_material(Color c) const;
// Other properties of the position
Color side_to_move() const;
- int startpos_ply_counter() const;
+ int game_ply() const;
bool is_chess960() const;
Thread* this_thread() const;
int64_t nodes_searched() const;
void set_nodes_searched(int64_t n);
- template<bool SkipRepetition> bool is_draw() const;
+ bool is_draw() const;
// Position consistency check, for debugging
bool pos_is_ok(int* failedStep = NULL) const;
void flip();
- // Global initialization
- static void init();
-
private:
// Initialization helpers (used while setting up a position)
void clear();
- void put_piece(Piece p, Square s);
void set_castle_right(Color c, Square rfrom);
- // Helper template functions
- template<bool Do> void do_castle_move(Move m);
- template<bool FindPinned> Bitboard hidden_checkers() const;
+ // Helper functions
+ void do_castle(Square kfrom, Square kto, Square rfrom, Square rto);
+ Bitboard hidden_checkers(Square ksq, Color c, Color toMove) const;
+ void put_piece(Square s, Color c, PieceType pt);
+ void remove_piece(Square s, Color c, PieceType pt);
+ void move_piece(Square from, Square to, Color c, PieceType pt);
// Computing hash keys from scratch (for initialization and debugging)
Key compute_key() const;
Value compute_non_pawn_material(Color c) const;
// Board and pieces
- Piece board[64]; // [square]
- Bitboard byTypeBB[8]; // [pieceType]
- Bitboard byColorBB[2]; // [color]
- int pieceCount[2][8]; // [color][pieceType]
- Square pieceList[2][8][16]; // [color][pieceType][index]
- int index[64]; // [square]
+ Piece board[SQUARE_NB];
+ Bitboard byTypeBB[PIECE_TYPE_NB];
+ Bitboard byColorBB[COLOR_NB];
+ int pieceCount[COLOR_NB][PIECE_TYPE_NB];
+ Square pieceList[COLOR_NB][PIECE_TYPE_NB][16];
+ int index[SQUARE_NB];
// Other info
- int castleRightsMask[64]; // [square]
- Square castleRookSquare[2][2]; // [color][side]
- Bitboard castlePath[2][2]; // [color][side]
+ int castleRightsMask[SQUARE_NB];
+ Square castleRookSquare[COLOR_NB][CASTLING_SIDE_NB];
+ Bitboard castlePath[COLOR_NB][CASTLING_SIDE_NB];
StateInfo startState;
int64_t nodes;
- int startPosPly;
+ int gamePly;
Color sideToMove;
Thread* thisThread;
StateInfo* st;
int chess960;
-
- // Static variables
- static Score pieceSquareTable[16][64]; // [piece][square]
- static Key zobrist[2][8][64]; // [color][pieceType][square]/[piece count]
- static Key zobEp[8]; // [file]
- static Key zobCastle[16]; // [castleRight]
- static Key zobSideToMove;
- static Key zobExclusion;
};
inline int64_t Position::nodes_searched() const {
return board[s];
}
-inline Piece Position::piece_moved(Move m) const {
+inline Piece Position::moved_piece(Move m) const {
return board[from_sq(m)];
}
-inline bool Position::is_empty(Square s) const {
+inline bool Position::empty(Square s) const {
return board[s] == NO_PIECE;
}
return byColorBB[c] & (byTypeBB[pt1] | byTypeBB[pt2]);
}
-inline int Position::piece_count(Color c, PieceType pt) const {
- return pieceCount[c][pt];
+template<PieceType Pt> inline int Position::count(Color c) const {
+ return pieceCount[c][Pt];
}
-inline const Square* Position::piece_list(Color c, PieceType pt) const {
- return pieceList[c][pt];
+template<PieceType Pt> inline const Square* Position::list(Color c) const {
+ return pieceList[c][Pt];
}
inline Square Position::ep_square() const {
return st->checkersBB;
}
-inline bool Position::in_check() const {
- return st->checkersBB != 0;
-}
-
inline Bitboard Position::discovered_check_candidates() const {
- return hidden_checkers<false>();
+ return hidden_checkers(king_square(~sideToMove), sideToMove, sideToMove);
}
-inline Bitboard Position::pinned_pieces() const {
- return hidden_checkers<true>();
+inline Bitboard Position::pinned_pieces(Color toMove) const {
+ return hidden_checkers(king_square(toMove), ~toMove, toMove);
}
-inline bool Position::pawn_is_passed(Color c, Square s) const {
+inline bool Position::pawn_passed(Color c, Square s) const {
return !(pieces(~c, PAWN) & passed_pawn_mask(c, s));
}
-inline Key Position::key() const {
- return st->key;
+inline bool Position::passed_pawn_push(Move m) const {
+
+ return type_of(moved_piece(m)) == PAWN
+ && pawn_passed(sideToMove, to_sq(m));
}
-inline Key Position::exclusion_key() const {
- return st->key ^ zobExclusion;
+inline Key Position::key() const {
+ return st->key;
}
inline Key Position::pawn_key() const {
return st->materialKey;
}
-inline Score Position::psq_delta(Piece p, Square from, Square to) const {
- return pieceSquareTable[p][to] - pieceSquareTable[p][from];
-}
-
inline Score Position::psq_score() const {
- return st->psqScore;
+ return st->psq;
}
inline Value Position::non_pawn_material(Color c) const {
return st->npMaterial[c];
}
-inline bool Position::is_passed_pawn_push(Move m) const {
-
- return type_of(piece_moved(m)) == PAWN
- && pawn_is_passed(sideToMove, to_sq(m));
-}
-
-inline int Position::startpos_ply_counter() const {
- return startPosPly + st->pliesFromNull; // HACK
+inline int Position::game_ply() const {
+ return gamePly;
}
inline bool Position::opposite_bishops() const {
return chess960;
}
-inline bool Position::is_capture_or_promotion(Move m) const {
+inline bool Position::capture_or_promotion(Move m) const {
assert(is_ok(m));
- return is_special(m) ? !is_castle(m) : !is_empty(to_sq(m));
+ return type_of(m) ? type_of(m) != CASTLE : !empty(to_sq(m));
}
-inline bool Position::is_capture(Move m) const {
+inline bool Position::capture(Move m) const {
// Note that castle is coded as "king captures the rook"
assert(is_ok(m));
- return (!is_empty(to_sq(m)) && !is_castle(m)) || is_enpassant(m);
+ return (!empty(to_sq(m)) && type_of(m) != CASTLE) || type_of(m) == ENPASSANT;
}
inline PieceType Position::captured_piece_type() const {
return thisThread;
}
-#endif // !defined(POSITION_H_INCLUDED)
+inline void Position::put_piece(Square s, Color c, PieceType pt) {
+
+ board[s] = make_piece(c, pt);
+ byTypeBB[ALL_PIECES] |= s;
+ byTypeBB[pt] |= s;
+ byColorBB[c] |= s;
+ pieceCount[c][ALL_PIECES]++;
+ index[s] = pieceCount[c][pt]++;
+ pieceList[c][pt][index[s]] = s;
+}
+
+inline void Position::move_piece(Square from, Square to, Color c, PieceType pt) {
+
+ // index[from] is not updated and becomes stale. This works as long
+ // as index[] is accessed just by known occupied squares.
+ Bitboard from_to_bb = SquareBB[from] ^ SquareBB[to];
+ byTypeBB[ALL_PIECES] ^= from_to_bb;
+ byTypeBB[pt] ^= from_to_bb;
+ byColorBB[c] ^= from_to_bb;
+ board[from] = NO_PIECE;
+ board[to] = make_piece(c, pt);
+ index[to] = index[from];
+ pieceList[c][pt][index[to]] = to;
+}
+
+inline void Position::remove_piece(Square s, Color c, PieceType pt) {
+
+ // WARNING: This is not a reversible operation. If we remove a piece in
+ // do_move() and then replace it in undo_move() we will put it at the end of
+ // the list and not in its original place, it means index[] and pieceList[]
+ // are not guaranteed to be invariant to a do_move() + undo_move() sequence.
+ byTypeBB[ALL_PIECES] ^= s;
+ byTypeBB[pt] ^= s;
+ byColorBB[c] ^= s;
+ /* board[s] = NO_PIECE; */ // Not needed, will be overwritten by capturing
+ pieceCount[c][ALL_PIECES]--;
+ Square lastSquare = pieceList[c][pt][--pieceCount[c][pt]];
+ index[lastSquare] = index[s];
+ pieceList[c][pt][index[lastSquare]] = lastSquare;
+ pieceList[c][pt][pieceCount[c][pt]] = SQ_NONE;
+}
+
+#endif // #ifndef POSITION_H_INCLUDED
projects / stockfish / blobdiff