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>
};
-/// 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), a 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[COLOR_NB];
int castleRights, rule50, pliesFromNull;
- Score psqScore;
+ Score psq;
Square epSquare;
Key key;
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(const Position& p, Thread* t) { *this = p; thisThread = t; }
Position(const std::string& f, bool c960, Thread* t) { set(f, c960, t); }
Position& operator=(const Position&);
+ static void init();
// Text input/output
void set(const std::string& fen, bool isChess960, Thread* th);
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;
// Checking
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 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 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;
- int see_asymm(Move m, int asymmThreshold) const;
- template <bool Asymmetric> int do_see(Move m, int asymmThreshold) const; //FIXME: private!!
// Accessing hash keys
Key key() const;
// 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
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;
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 functions
void do_castle(Square kfrom, Square kto, Square rfrom, Square rto);
- template<bool FindPinned> Bitboard hidden_checkers() const;
+ 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;
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 {
}
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 ^ Zobrist::exclusion;
+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::game_ply() const {
return gamePly;
}
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 type_of(m) ? type_of(m) != CASTLE : !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)) && type_of(m) != CASTLE) || type_of(m) == ENPASSANT;
+ 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