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) 2015-2016 Marco Costalba, Joona Kiiski, Gary Linscott, Tord Romstad
+ Copyright (C) 2015-2020 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
int castlingRights;
int rule50;
int pliesFromNull;
- Score psq;
Square epSquare;
// Not copied when making a move (will be recomputed anyhow)
Piece capturedPiece;
StateInfo* previous;
Bitboard blockersForKing[COLOR_NB];
- Bitboard pinnersForKing[COLOR_NB];
+ Bitboard pinners[COLOR_NB];
Bitboard checkSquares[PIECE_TYPE_NB];
+ int repetition;
};
-// In a std::deque references to elements are unaffected upon resizing
+/// A list to keep track of the position states along the setup moves (from the
+/// start position to the position just before the search starts). Needed by
+/// 'draw by repetition' detection. Use a std::deque because pointers to
+/// elements are not invalidated upon list resizing.
typedef std::unique_ptr<std::deque<StateInfo>> StateListPtr;
const std::string fen() const;
// Position representation
- Bitboard pieces() const;
Bitboard pieces(PieceType pt) const;
Bitboard pieces(PieceType pt1, PieceType pt2) const;
Bitboard pieces(Color c) const;
Square ep_square() const;
bool empty(Square s) const;
template<PieceType Pt> int count(Color c) const;
+ template<PieceType Pt> int count() const;
template<PieceType Pt> const Square* squares(Color c) const;
template<PieceType Pt> Square square(Color c) const;
+ bool is_on_semiopen_file(Color c, Square s) const;
// Castling
- int can_castle(Color c) const;
- int can_castle(CastlingRight cr) const;
- bool castling_impeded(CastlingRight cr) const;
- Square castling_rook_square(CastlingRight cr) const;
+ int castling_rights(Color c) const;
+ bool can_castle(CastlingRights cr) const;
+ bool castling_impeded(CastlingRights cr) const;
+ Square castling_rook_square(CastlingRights cr) const;
// Checking
Bitboard checkers() const;
- Bitboard discovered_check_candidates() const;
- Bitboard pinned_pieces(Color c) const;
+ Bitboard blockers_for_king(Color c) const;
Bitboard check_squares(PieceType pt) const;
+ bool is_discovery_check_on_king(Color c, Move m) const;
// Attacks to/from a given square
Bitboard attackers_to(Square s) const;
Bitboard attackers_to(Square s, Bitboard occupied) const;
- Bitboard attacks_from(Piece pc, Square s) const;
+ Bitboard attacks_from(PieceType pt, Square s) const;
template<PieceType> Bitboard attacks_from(Square s) const;
template<PieceType> Bitboard attacks_from(Square s, Color c) const;
Bitboard slider_blockers(Bitboard sliders, Square s, Bitboard& pinners) const;
// Piece specific
bool pawn_passed(Color c, Square s) const;
bool opposite_bishops() const;
+ int pawns_on_same_color_squares(Color c, Square s) const;
// Doing and undoing moves
- void do_move(Move m, StateInfo& st, bool givesCheck);
+ void do_move(Move m, StateInfo& newSt);
+ void do_move(Move m, StateInfo& newSt, bool givesCheck);
void undo_move(Move m);
- void do_null_move(StateInfo& st);
+ void do_null_move(StateInfo& newSt);
void undo_null_move();
// Static Exchange Evaluation
- bool see_ge(Move m, Value value) const;
+ bool see_ge(Move m, Value threshold = VALUE_ZERO) const;
// Accessing hash keys
Key key() const;
// Other properties of the position
Color side_to_move() const;
- Phase game_phase() const;
int game_ply() const;
bool is_chess960() const;
Thread* this_thread() const;
- uint64_t nodes_searched() const;
- bool is_draw() const;
+ bool is_draw(int ply) const;
+ bool has_game_cycle(int ply) const;
+ bool has_repeated() const;
int rule50_count() const;
Score psq_score() const;
Value non_pawn_material(Color c) const;
+ Value non_pawn_material() const;
// Position consistency check, for debugging
- bool pos_is_ok(int* failedStep = nullptr) const;
+ bool pos_is_ok() const;
void flip();
private:
// Other helpers
void put_piece(Piece pc, Square s);
- void remove_piece(Piece pc, Square s);
- void move_piece(Piece pc, Square from, Square to);
+ void remove_piece(Square s);
+ void move_piece(Square from, Square to);
template<bool Do>
void do_castling(Color us, Square from, Square& to, Square& rfrom, Square& rto);
int castlingRightsMask[SQUARE_NB];
Square castlingRookSquare[CASTLING_RIGHT_NB];
Bitboard castlingPath[CASTLING_RIGHT_NB];
- uint64_t nodes;
int gamePly;
Color sideToMove;
+ Score psq;
Thread* thisThread;
StateInfo* st;
bool chess960;
};
-extern std::ostream& operator<<(std::ostream& os, Position& pos);
+namespace PSQT {
+ extern Score psq[PIECE_NB][SQUARE_NB];
+}
+
+extern std::ostream& operator<<(std::ostream& os, const Position& pos);
inline Color Position::side_to_move() const {
return sideToMove;
}
-inline bool Position::empty(Square s) const {
- return board[s] == NO_PIECE;
-}
-
inline Piece Position::piece_on(Square s) const {
+ assert(is_ok(s));
return board[s];
}
-inline Piece Position::moved_piece(Move m) const {
- return board[from_sq(m)];
+inline bool Position::empty(Square s) const {
+ return piece_on(s) == NO_PIECE;
}
-inline Bitboard Position::pieces() const {
- return byTypeBB[ALL_PIECES];
+inline Piece Position::moved_piece(Move m) const {
+ return piece_on(from_sq(m));
}
-inline Bitboard Position::pieces(PieceType pt) const {
+inline Bitboard Position::pieces(PieceType pt = ALL_PIECES) const {
return byTypeBB[pt];
}
inline Bitboard Position::pieces(PieceType pt1, PieceType pt2) const {
- return byTypeBB[pt1] | byTypeBB[pt2];
+ return pieces(pt1) | pieces(pt2);
}
inline Bitboard Position::pieces(Color c) const {
}
inline Bitboard Position::pieces(Color c, PieceType pt) const {
- return byColorBB[c] & byTypeBB[pt];
+ return pieces(c) & pieces(pt);
}
inline Bitboard Position::pieces(Color c, PieceType pt1, PieceType pt2) const {
- return byColorBB[c] & (byTypeBB[pt1] | byTypeBB[pt2]);
+ return pieces(c) & (pieces(pt1) | pieces(pt2));
}
template<PieceType Pt> inline int Position::count(Color c) const {
return pieceCount[make_piece(c, Pt)];
}
+template<PieceType Pt> inline int Position::count() const {
+ return count<Pt>(WHITE) + count<Pt>(BLACK);
+}
+
template<PieceType Pt> inline const Square* Position::squares(Color c) const {
return pieceList[make_piece(c, Pt)];
}
template<PieceType Pt> inline Square Position::square(Color c) const {
assert(pieceCount[make_piece(c, Pt)] == 1);
- return pieceList[make_piece(c, Pt)][0];
+ return squares<Pt>(c)[0];
}
inline Square Position::ep_square() const {
return st->epSquare;
}
-inline int Position::can_castle(CastlingRight cr) const {
+inline bool Position::is_on_semiopen_file(Color c, Square s) const {
+ return !(pieces(c, PAWN) & file_bb(s));
+}
+
+inline bool Position::can_castle(CastlingRights cr) const {
return st->castlingRights & cr;
}
-inline int Position::can_castle(Color c) const {
- return st->castlingRights & ((WHITE_OO | WHITE_OOO) << (2 * c));
+inline int Position::castling_rights(Color c) const {
+ return c & CastlingRights(st->castlingRights);
}
-inline bool Position::castling_impeded(CastlingRight cr) const {
- return byTypeBB[ALL_PIECES] & castlingPath[cr];
+inline bool Position::castling_impeded(CastlingRights cr) const {
+ assert(cr == WHITE_OO || cr == WHITE_OOO || cr == BLACK_OO || cr == BLACK_OOO);
+
+ return pieces() & castlingPath[cr];
}
-inline Square Position::castling_rook_square(CastlingRight cr) const {
+inline Square Position::castling_rook_square(CastlingRights cr) const {
+ assert(cr == WHITE_OO || cr == WHITE_OOO || cr == BLACK_OO || cr == BLACK_OOO);
+
return castlingRookSquare[cr];
}
template<PieceType Pt>
inline Bitboard Position::attacks_from(Square s) const {
- return Pt == BISHOP || Pt == ROOK ? attacks_bb<Pt>(s, byTypeBB[ALL_PIECES])
+ static_assert(Pt != PAWN, "Pawn attacks need color");
+
+ return Pt == BISHOP || Pt == ROOK ? attacks_bb<Pt>(s, pieces())
: Pt == QUEEN ? attacks_from<ROOK>(s) | attacks_from<BISHOP>(s)
- : StepAttacksBB[Pt][s];
+ : PseudoAttacks[Pt][s];
}
template<>
inline Bitboard Position::attacks_from<PAWN>(Square s, Color c) const {
- return StepAttacksBB[make_piece(c, PAWN)][s];
+ return PawnAttacks[c][s];
}
-inline Bitboard Position::attacks_from(Piece pc, Square s) const {
- return attacks_bb(pc, s, byTypeBB[ALL_PIECES]);
+inline Bitboard Position::attacks_from(PieceType pt, Square s) const {
+ return attacks_bb(pt, s, pieces());
}
inline Bitboard Position::attackers_to(Square s) const {
- return attackers_to(s, byTypeBB[ALL_PIECES]);
+ return attackers_to(s, pieces());
}
inline Bitboard Position::checkers() const {
return st->checkersBB;
}
-inline Bitboard Position::discovered_check_candidates() const {
- return st->blockersForKing[~sideToMove] & pieces(sideToMove);
-}
-
-inline Bitboard Position::pinned_pieces(Color c) const {
- return st->blockersForKing[c] & pieces(c);
+inline Bitboard Position::blockers_for_king(Color c) const {
+ return st->blockersForKing[c];
}
inline Bitboard Position::check_squares(PieceType pt) const {
return st->checkSquares[pt];
}
+inline bool Position::is_discovery_check_on_king(Color c, Move m) const {
+ return st->blockersForKing[c] & from_sq(m);
+}
+
inline bool Position::pawn_passed(Color c, Square s) const {
- return !(pieces(~c, PAWN) & passed_pawn_mask(c, s));
+ return !(pieces(~c, PAWN) & passed_pawn_span(c, s));
}
inline bool Position::advanced_pawn_push(Move m) const {
return type_of(moved_piece(m)) == PAWN
- && relative_rank(sideToMove, from_sq(m)) > RANK_4;
+ && relative_rank(sideToMove, to_sq(m)) > RANK_5;
+}
+
+inline int Position::pawns_on_same_color_squares(Color c, Square s) const {
+ return popcount(pieces(c, PAWN) & ((DarkSquares & s) ? DarkSquares : ~DarkSquares));
}
inline Key Position::key() const {
}
inline Score Position::psq_score() const {
- return st->psq;
+ return psq;
}
inline Value Position::non_pawn_material(Color c) const {
return st->nonPawnMaterial[c];
}
+inline Value Position::non_pawn_material() const {
+ return non_pawn_material(WHITE) + non_pawn_material(BLACK);
+}
+
inline int Position::game_ply() const {
return gamePly;
}
return st->rule50;
}
-inline uint64_t Position::nodes_searched() const {
- return nodes;
-}
-
inline bool Position::opposite_bishops() const {
- return pieceCount[W_BISHOP] == 1
- && pieceCount[B_BISHOP] == 1
+ return count<BISHOP>(WHITE) == 1
+ && count<BISHOP>(BLACK) == 1
&& opposite_colors(square<BISHOP>(WHITE), square<BISHOP>(BLACK));
}
index[s] = pieceCount[pc]++;
pieceList[pc][index[s]] = s;
pieceCount[make_piece(color_of(pc), ALL_PIECES)]++;
+ psq += PSQT::psq[pc][s];
}
-inline void Position::remove_piece(Piece pc, Square s) {
+inline void Position::remove_piece(Square s) {
// 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 invariant to a do_move() + undo_move() sequence.
+ Piece pc = board[s];
byTypeBB[ALL_PIECES] ^= s;
byTypeBB[type_of(pc)] ^= s;
byColorBB[color_of(pc)] ^= s;
pieceList[pc][index[lastSquare]] = lastSquare;
pieceList[pc][pieceCount[pc]] = SQ_NONE;
pieceCount[make_piece(color_of(pc), ALL_PIECES)]--;
+ psq -= PSQT::psq[pc][s];
}
-inline void Position::move_piece(Piece pc, Square from, Square to) {
+inline void Position::move_piece(Square from, Square to) {
// 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[type_of(pc)] ^= from_to_bb;
- byColorBB[color_of(pc)] ^= from_to_bb;
+ Piece pc = board[from];
+ Bitboard fromTo = from | to;
+ byTypeBB[ALL_PIECES] ^= fromTo;
+ byTypeBB[type_of(pc)] ^= fromTo;
+ byColorBB[color_of(pc)] ^= fromTo;
board[from] = NO_PIECE;
board[to] = pc;
index[to] = index[from];
pieceList[pc][index[to]] = to;
+ psq += PSQT::psq[pc][to] - PSQT::psq[pc][from];
+}
+
+inline void Position::do_move(Move m, StateInfo& newSt) {
+ do_move(m, newSt, gives_check(m));
}
#endif // #ifndef POSITION_H_INCLUDED
projects / stockfish / blobdiff