/*
Stockfish, a UCI chess playing engine derived from Glaurung 2.1
Copyright (C) 2004-2008 Tord Romstad (Glaurung author)
- Copyright (C) 2008-2009 Marco Costalba
+ Copyright (C) 2008-2010 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
enum MoveType {
CAPTURE,
- NON_CAPTURE
+ NON_CAPTURE,
+ CHECK,
+ EVASION
};
- // Functions
- bool castling_is_check(const Position&, CastlingSide);
-
// Helper templates
template<CastlingSide Side>
- MoveStack* generate_castle_moves(const Position& pos, MoveStack* mlist);
-
- template<Color Us>
- MoveStack* generate_pawn_blocking_evasions(const Position&, Bitboard, Bitboard, MoveStack*);
-
- template<Color Us>
- MoveStack* generate_pawn_captures(const Position& pos, MoveStack* mlist);
-
- template<Color Us, SquareDelta Diagonal>
- MoveStack* generate_pawn_captures_diagonal(MoveStack* mlist, Bitboard pawns, Bitboard enemyPieces, bool promotion);
-
- template<Color Us>
- MoveStack* generate_pawn_noncaptures(const Position& pos, MoveStack* mlist);
+ MoveStack* generate_castle_moves(const Position&, MoveStack*);
- template<Color Us>
- MoveStack* generate_pawn_checks(const Position&, Bitboard, Square, MoveStack*);
+ template<Color Us, MoveType Type>
+ MoveStack* generate_pawn_moves(const Position&, MoveStack*, Bitboard, Square);
- template<Color Us, SquareDelta Direction>
- inline Bitboard move_pawns(Bitboard p) {
-
- if (Direction == DELTA_N)
- return Us == WHITE ? p << 8 : p >> 8;
- else if (Direction == DELTA_NE)
- return Us == WHITE ? p << 9 : p >> 7;
- else if (Direction == DELTA_NW)
- return Us == WHITE ? p << 7 : p >> 9;
- else
- return p;
- }
-
- // Template generate_piece_checks() with specializations
- template<PieceType>
- MoveStack* generate_piece_checks(const Position&, MoveStack*, Color, Bitboard, Square);
-
- template<>
- inline MoveStack* generate_piece_checks<PAWN>(const Position& p, MoveStack* m, Color us, Bitboard dc, Square ksq) {
-
- return (us == WHITE ? generate_pawn_checks<WHITE>(p, dc, ksq, m)
- : generate_pawn_checks<BLACK>(p, dc, ksq, m));
- }
-
- // Template generate_piece_moves() with specializations and overloads
+ // Template generate_piece_moves (captures and non-captures) with specializations and overloads
template<PieceType>
- MoveStack* generate_piece_moves(const Position&, MoveStack*, Color us, Bitboard);
+ MoveStack* generate_piece_moves(const Position&, MoveStack*, Color, Bitboard);
template<>
MoveStack* generate_piece_moves<KING>(const Position&, MoveStack*, Color, Bitboard);
template<PieceType Piece, MoveType Type>
- inline MoveStack* generate_piece_moves(const Position& p, MoveStack* m, Color us) {
+ inline MoveStack* generate_piece_moves(const Position& p, MoveStack* m, Color us, Bitboard t) {
- assert(Piece == PAWN);
+ assert(Piece == PAWN);
+ assert(Type == CAPTURE || Type == NON_CAPTURE || Type == EVASION);
- if (Type == CAPTURE)
- return (us == WHITE ? generate_pawn_captures<WHITE>(p, m)
- : generate_pawn_captures<BLACK>(p, m));
- else
- return (us == WHITE ? generate_pawn_noncaptures<WHITE>(p, m)
- : generate_pawn_noncaptures<BLACK>(p, m));
+ return (us == WHITE ? generate_pawn_moves<WHITE, Type>(p, m, t, SQ_NONE)
+ : generate_pawn_moves<BLACK, Type>(p, m, t, SQ_NONE));
}
+ // Templates for non-capture checks generation
+
+ template<PieceType Piece>
+ MoveStack* generate_discovered_checks(const Position&, MoveStack*, Square);
+
template<PieceType>
- MoveStack* generate_piece_moves(const Position&, MoveStack*, Color us, Bitboard, Bitboard);
+ MoveStack* generate_direct_checks(const Position&, MoveStack*, Color, Bitboard, Square);
template<>
- inline MoveStack* generate_piece_moves<PAWN>(const Position& p, MoveStack* m,
- Color us, Bitboard t, Bitboard pnd) {
+ inline MoveStack* generate_direct_checks<PAWN>(const Position& p, MoveStack* m, Color us, Bitboard dc, Square ksq) {
- return (us == WHITE ? generate_pawn_blocking_evasions<WHITE>(p, pnd, t, m)
- : generate_pawn_blocking_evasions<BLACK>(p, pnd, t, m));
+ return (us == WHITE ? generate_pawn_moves<WHITE, CHECK>(p, m, dc, ksq)
+ : generate_pawn_moves<BLACK, CHECK>(p, m, dc, ksq));
}
}
////
-/// generate_captures generates() all pseudo-legal captures and queen
-/// promotions. The return value is the number of moves generated.
+/// generate_captures() generates all pseudo-legal captures and queen
+/// promotions. Returns a pointer to the end of the move list.
MoveStack* generate_captures(const Position& pos, MoveStack* mlist) {
mlist = generate_piece_moves<ROOK>(pos, mlist, us, target);
mlist = generate_piece_moves<BISHOP>(pos, mlist, us, target);
mlist = generate_piece_moves<KNIGHT>(pos, mlist, us, target);
- mlist = generate_piece_moves<PAWN, CAPTURE>(pos, mlist, us);
+ mlist = generate_piece_moves<PAWN, CAPTURE>(pos, mlist, us, target);
return generate_piece_moves<KING>(pos, mlist, us, target);
}
/// generate_noncaptures() generates all pseudo-legal non-captures and
-/// underpromotions. The return value is the number of moves generated.
+/// underpromotions. Returns a pointer to the end of the move list.
MoveStack* generate_noncaptures(const Position& pos, MoveStack* mlist) {
Color us = pos.side_to_move();
Bitboard target = pos.empty_squares();
- mlist = generate_piece_moves<PAWN, NON_CAPTURE>(pos, mlist, us);
+ mlist = generate_piece_moves<PAWN, NON_CAPTURE>(pos, mlist, us, target);
mlist = generate_piece_moves<KNIGHT>(pos, mlist, us, target);
mlist = generate_piece_moves<BISHOP>(pos, mlist, us, target);
mlist = generate_piece_moves<ROOK>(pos, mlist, us, target);
}
-/// generate_non_capture_checks() generates all pseudo-legal non-capturing,
-/// non-promoting checks. It returns the number of generated moves.
+/// generate_non_evasions() generates all pseudo-legal captures and
+/// non-captures. Returns a pointer to the end of the move list.
-MoveStack* generate_non_capture_checks(const Position& pos, MoveStack* mlist, Bitboard dc) {
+MoveStack* generate_non_evasions(const Position& pos, MoveStack* mlist) {
assert(pos.is_ok());
assert(!pos.is_check());
Color us = pos.side_to_move();
- Square ksq = pos.king_square(opposite_color(us));
+ Bitboard target = pos.pieces_of_color(opposite_color(us));
- assert(pos.piece_on(ksq) == piece_of_color_and_type(opposite_color(us), KING));
+ mlist = generate_piece_moves<PAWN, CAPTURE>(pos, mlist, us, target);
+ mlist = generate_piece_moves<PAWN, NON_CAPTURE>(pos, mlist, us, pos.empty_squares());
- // Pieces moves
- mlist = generate_piece_checks<PAWN>(pos, mlist, us, dc, ksq);
- mlist = generate_piece_checks<KNIGHT>(pos, mlist, us, dc, ksq);
- mlist = generate_piece_checks<BISHOP>(pos, mlist, us, dc, ksq);
- mlist = generate_piece_checks<ROOK>(pos, mlist, us, dc, ksq);
- mlist = generate_piece_checks<QUEEN>(pos, mlist, us, dc, ksq);
- mlist = generate_piece_checks<KING>(pos, mlist, us, dc, ksq);
-
- // Castling moves that give check. Very rare but nice to have!
- if ( pos.can_castle_queenside(us)
- && (square_rank(ksq) == square_rank(pos.king_square(us)) || square_file(ksq) == FILE_D)
- && castling_is_check(pos, QUEEN_SIDE))
- mlist = generate_castle_moves<QUEEN_SIDE>(pos, mlist);
-
- if ( pos.can_castle_kingside(us)
- && (square_rank(ksq) == square_rank(pos.king_square(us)) || square_file(ksq) == FILE_F)
- && castling_is_check(pos, KING_SIDE))
- mlist = generate_castle_moves<KING_SIDE>(pos, mlist);
-
- return mlist;
+ target |= pos.empty_squares();
+
+ mlist = generate_piece_moves<KNIGHT>(pos, mlist, us, target);
+ mlist = generate_piece_moves<BISHOP>(pos, mlist, us, target);
+ mlist = generate_piece_moves<ROOK>(pos, mlist, us, target);
+ mlist = generate_piece_moves<QUEEN>(pos, mlist, us, target);
+ mlist = generate_piece_moves<KING>(pos, mlist, us, target);
+ mlist = generate_castle_moves<KING_SIDE>(pos, mlist);
+ return generate_castle_moves<QUEEN_SIDE>(pos, mlist);
}
-/// generate_evasions() generates all check evasions when the side to move is
-/// in check. Unlike the other move generation functions, this one generates
-/// only legal moves. It returns the number of generated moves.
+/// generate_non_capture_checks() generates all pseudo-legal non-captures and knight
+/// underpromotions that give check. Returns a pointer to the end of the move list.
-MoveStack* generate_evasions(const Position& pos, MoveStack* mlist, Bitboard pinned) {
+MoveStack* generate_non_capture_checks(const Position& pos, MoveStack* mlist) {
assert(pos.is_ok());
- assert(pos.is_check());
+ assert(!pos.is_check());
- Square from, to;
+ Bitboard b, dc;
+ Square from;
Color us = pos.side_to_move();
- Color them = opposite_color(us);
- Square ksq = pos.king_square(us);
+ Square ksq = pos.king_square(opposite_color(us));
- assert(pos.piece_on(ksq) == piece_of_color_and_type(us, KING));
+ assert(pos.piece_on(ksq) == piece_of_color_and_type(opposite_color(us), KING));
- // The bitboard of occupied pieces without our king
- Bitboard b_noKing = pos.occupied_squares();
- clear_bit(&b_noKing, ksq);
+ // Discovered non-capture checks
+ b = dc = pos.discovered_check_candidates(us);
- // Find squares attacked by slider checkers, we will
- // remove them from king evasions set so to avoid a couple
- // of cycles in the slow king evasions legality check loop
- // and to be able to use square_is_attacked().
- Bitboard checkers = pos.checkers();
- Bitboard checkersAttacks = EmptyBoardBB;
- Bitboard b = checkers & (pos.queens() | pos.bishops());
while (b)
{
- from = pop_1st_bit(&b);
- checkersAttacks |= bishop_attacks_bb(from, b_noKing);
+ from = pop_1st_bit(&b);
+ switch (pos.type_of_piece_on(from))
+ {
+ case PAWN: /* Will be generated togheter with pawns direct checks */ break;
+ case KNIGHT: mlist = generate_discovered_checks<KNIGHT>(pos, mlist, from); break;
+ case BISHOP: mlist = generate_discovered_checks<BISHOP>(pos, mlist, from); break;
+ case ROOK: mlist = generate_discovered_checks<ROOK>(pos, mlist, from); break;
+ case KING: mlist = generate_discovered_checks<KING>(pos, mlist, from); break;
+ default: assert(false); break;
+ }
}
- b = checkers & (pos.queens() | pos.rooks());
- while (b)
- {
- from = pop_1st_bit(&b);
- checkersAttacks |= rook_attacks_bb(from, b_noKing);
- }
+ // Direct non-capture checks
+ mlist = generate_direct_checks<PAWN>(pos, mlist, us, dc, ksq);
+ mlist = generate_direct_checks<KNIGHT>(pos, mlist, us, dc, ksq);
+ mlist = generate_direct_checks<BISHOP>(pos, mlist, us, dc, ksq);
+ mlist = generate_direct_checks<ROOK>(pos, mlist, us, dc, ksq);
+ return generate_direct_checks<QUEEN>(pos, mlist, us, dc, ksq);
+}
- // Generate evasions for king
- Bitboard b1 = pos.piece_attacks<KING>(ksq) & ~pos.pieces_of_color(us) & ~checkersAttacks;
- while (b1)
- {
- to = pop_1st_bit(&b1);
- // Note that we can use square_is_attacked() only because we
- // have already removed slider checkers.
- if (!pos.square_is_attacked(to, them))
- (*mlist++).move = make_move(ksq, to);
- }
- // Generate evasions for other pieces only if not double check. We use a
- // simple bit twiddling hack here rather than calling count_1s in order to
- // save some time (we know that pos.checkers() has at most two nonzero bits).
- if (!(checkers & (checkers - 1))) // Only one bit set?
- {
- Square checksq = first_1(checkers);
+/// generate_evasions() generates all pseudo-legal check evasions when
+/// the side to move is in check. Returns a pointer to the end of the move list.
- assert(pos.color_of_piece_on(checksq) == them);
+MoveStack* generate_evasions(const Position& pos, MoveStack* mlist) {
- // Generate captures of the checking piece
+ assert(pos.is_ok());
+ assert(pos.is_check());
- // Pawn captures
- b1 = pos.pawn_attacks(them, checksq) & pos.pawns(us) & ~pinned;
- while (b1)
- {
- from = pop_1st_bit(&b1);
- if (relative_rank(us, checksq) == RANK_8)
- {
- (*mlist++).move = make_promotion_move(from, checksq, QUEEN);
- (*mlist++).move = make_promotion_move(from, checksq, ROOK);
- (*mlist++).move = make_promotion_move(from, checksq, BISHOP);
- (*mlist++).move = make_promotion_move(from, checksq, KNIGHT);
- } else
- (*mlist++).move = make_move(from, checksq);
- }
+ Bitboard b, target;
+ Square from, checksq;
+ int checkersCnt = 0;
+ Color us = pos.side_to_move();
+ Square ksq = pos.king_square(us);
+ Bitboard checkers = pos.checkers();
+ Bitboard sliderAttacks = EmptyBoardBB;
- // Pieces captures
- b1 = ( (pos.piece_attacks<KNIGHT>(checksq) & pos.knights(us))
- | (pos.piece_attacks<BISHOP>(checksq) & pos.bishops_and_queens(us))
- | (pos.piece_attacks<ROOK>(checksq) & pos.rooks_and_queens(us)) ) & ~pinned;
+ assert(pos.piece_on(ksq) == piece_of_color_and_type(us, KING));
+ assert(checkers);
- while (b1)
- {
- from = pop_1st_bit(&b1);
- (*mlist++).move = make_move(from, checksq);
- }
+ // Find squares attacked by slider checkers, we will remove
+ // them from the king evasions set so to early skip known
+ // illegal moves and avoid an useless legality check later.
+ b = checkers;
+ do
+ {
+ checkersCnt++;
+ checksq = pop_1st_bit(&b);
- // Blocking check evasions are possible only if the checking piece is
- // a slider.
- if (checkers & pos.sliders())
- {
- Bitboard blockSquares = squares_between(checksq, ksq);
-
- assert((pos.occupied_squares() & blockSquares) == EmptyBoardBB);
-
- if (blockSquares != EmptyBoardBB)
- {
- mlist = generate_piece_moves<PAWN>(pos, mlist, us, blockSquares, pinned);
- mlist = generate_piece_moves<KNIGHT>(pos, mlist, us, blockSquares, pinned);
- mlist = generate_piece_moves<BISHOP>(pos, mlist, us, blockSquares, pinned);
- mlist = generate_piece_moves<ROOK>(pos, mlist, us, blockSquares, pinned);
- mlist = generate_piece_moves<QUEEN>(pos, mlist, us, blockSquares, pinned);
- }
- }
+ assert(pos.color_of_piece_on(checksq) == opposite_color(us));
- // Finally, the special case of en passant captures. An en passant
- // capture can only be a check evasion if the check is not a discovered
- // check. If pos.ep_square() is set, the last move made must have been
- // a double pawn push. If, furthermore, the checking piece is a pawn,
- // an en passant check evasion may be possible.
- if (pos.ep_square() != SQ_NONE && (checkers & pos.pawns(them)))
+ switch (pos.type_of_piece_on(checksq))
{
- to = pos.ep_square();
- b1 = pos.pawn_attacks(them, to) & pos.pawns(us);
-
- // The checking pawn cannot be a discovered (bishop) check candidate
- // otherwise we were in check also before last double push move.
- assert(!bit_is_set(pos.discovered_check_candidates(them), checksq));
- assert(count_1s(b1) == 1 || count_1s(b1) == 2);
-
- b1 &= ~pinned;
- while (b1)
- {
- from = pop_1st_bit(&b1);
- // Move is always legal because checking pawn is not a discovered
- // check candidate and our capturing pawn has been already tested
- // against pinned pieces.
- (*mlist++).move = make_ep_move(from, to);
- }
+ case BISHOP: sliderAttacks |= BishopPseudoAttacks[checksq]; break;
+ case ROOK: sliderAttacks |= RookPseudoAttacks[checksq]; break;
+ case QUEEN:
+ // In case of a queen remove also squares attacked in the other direction to
+ // avoid possible illegal moves when queen and king are on adjacent squares.
+ if (direction_is_straight(checksq, ksq))
+ sliderAttacks |= RookPseudoAttacks[checksq] | pos.attacks_from<BISHOP>(checksq);
+ else
+ sliderAttacks |= BishopPseudoAttacks[checksq] | pos.attacks_from<ROOK>(checksq);
+ default:
+ break;
}
- }
- return mlist;
+ } while (b);
+
+ // Generate evasions for king, capture and non capture moves
+ b = pos.attacks_from<KING>(ksq) & ~pos.pieces_of_color(us) & ~sliderAttacks;
+ from = ksq;
+ SERIALIZE_MOVES(b);
+
+ // Generate evasions for other pieces only if not double check
+ if (checkersCnt > 1)
+ return mlist;
+
+ // Find squares where a blocking evasion or a capture of the
+ // checker piece is possible.
+ target = squares_between(checksq, ksq) | checkers;
+
+ mlist = generate_piece_moves<PAWN, EVASION>(pos, mlist, us, target);
+ mlist = generate_piece_moves<KNIGHT>(pos, mlist, us, target);
+ mlist = generate_piece_moves<BISHOP>(pos, mlist, us, target);
+ mlist = generate_piece_moves<ROOK>(pos, mlist, us, target);
+ return generate_piece_moves<QUEEN>(pos, mlist, us, target);
}
-/// generate_legal_moves() computes a complete list of legal moves in the
-/// current position. This function is not very fast, and should be used
-/// only in situations where performance is unimportant. It wouldn't be
-/// very hard to write an efficient legal move generator, but for the moment
-/// we don't need it.
+/// generate_moves() computes a complete list of legal or pseudo-legal moves in
+/// the current position. This function is not very fast, and should be used
+/// only in non time-critical paths.
-MoveStack* generate_legal_moves(const Position& pos, MoveStack* mlist) {
+MoveStack* generate_moves(const Position& pos, MoveStack* mlist, bool pseudoLegal) {
assert(pos.is_ok());
+ MoveStack *last, *cur = mlist;
Bitboard pinned = pos.pinned_pieces(pos.side_to_move());
- if (pos.is_check())
- return generate_evasions(pos, mlist, pinned);
-
// Generate pseudo-legal moves
- MoveStack* last = generate_captures(pos, mlist);
- last = generate_noncaptures(pos, last);
+ last = pos.is_check() ? generate_evasions(pos, mlist)
+ : generate_non_evasions(pos, mlist);
+ if (pseudoLegal)
+ return last;
// Remove illegal moves from the list
- for (MoveStack* cur = mlist; cur != last; cur++)
- if (!pos.pl_move_is_legal(cur->move, pinned))
- {
+ while (cur != last)
+ if (pos.pl_move_is_legal(cur->move, pinned))
+ cur++;
+ else
cur->move = (--last)->move;
- cur--;
- }
+
return last;
}
/// move_is_legal() takes a position and a (not necessarily pseudo-legal)
-/// move and a pinned pieces bitboard as input, and tests whether
-/// the move is legal. If the move is legal, the move itself is
-/// returned. If not, the function returns false. This function must
-/// only be used when the side to move is not in check.
+/// move and tests whether the move is legal. This version is not very fast
+/// and should be used only in non time-critical paths.
+
+bool move_is_legal(const Position& pos, const Move m) {
+
+ MoveStack mlist[MOVES_MAX];
+ MoveStack *cur, *last = generate_moves(pos, mlist, true);
+
+ for (cur = mlist; cur != last; cur++)
+ if (cur->move == m)
+ return pos.pl_move_is_legal(m, pos.pinned_pieces(pos.side_to_move()));
+
+ return false;
+}
+
+
+/// Fast version of move_is_legal() that takes a position a move and a
+/// bitboard of pinned pieces as input, and tests whether the move is legal.
bool move_is_legal(const Position& pos, const Move m, Bitboard pinned) {
assert(pos.is_ok());
- assert(!pos.is_check());
assert(move_is_ok(m));
assert(pinned == pos.pinned_pieces(pos.side_to_move()));
Color us = pos.side_to_move();
+ Color them = opposite_color(us);
Square from = move_from(m);
+ Square to = move_to(m);
Piece pc = pos.piece_on(from);
+ // Use a slower but simpler function for uncommon cases
+ if (move_is_special(m))
+ return move_is_legal(pos, m);
+
// If the from square is not occupied by a piece belonging to the side to
// move, the move is obviously not legal.
if (color_of_piece(pc) != us)
return false;
- Color them = opposite_color(us);
- Square to = move_to(m);
-
- // En passant moves
- if (move_is_ep(m))
- {
- // The piece must be a pawn and destination square must be the
- // en passant square.
- if ( type_of_piece(pc) != PAWN
- || to != pos.ep_square())
- return false;
-
- assert(pos.square_is_empty(to));
- assert(pos.piece_on(to - pawn_push(us)) == piece_of_color_and_type(them, PAWN));
-
- // The move is pseudo-legal, check if it is also legal
- return pos.pl_move_is_legal(m, pinned);
- }
-
- // Castling moves
- if (move_is_short_castle(m))
- {
- // The piece must be a king and side to move must still have
- // the right to castle kingside.
- if ( type_of_piece(pc) != KING
- ||!pos.can_castle_kingside(us))
- return false;
-
- assert(from == pos.king_square(us));
- assert(to == pos.initial_kr_square(us));
- assert(pos.piece_on(to) == piece_of_color_and_type(us, ROOK));
-
- Square g1 = relative_square(us, SQ_G1);
- Square f1 = relative_square(us, SQ_F1);
- Square s;
- bool illegal = false;
-
- // Check if any of the squares between king and rook
- // is occupied or under attack.
- for (s = Min(from, g1); s <= Max(from, g1); s++)
- if ( (s != from && s != to && !pos.square_is_empty(s))
- || pos.square_is_attacked(s, them))
- illegal = true;
-
- // Check if any of the squares between king and rook
- // is occupied.
- for (s = Min(to, f1); s <= Max(to, f1); s++)
- if (s != from && s != to && !pos.square_is_empty(s))
- illegal = true;
-
- return !illegal;
- }
-
- if (move_is_long_castle(m))
- {
- // The piece must be a king and side to move must still have
- // the right to castle kingside.
- if ( type_of_piece(pc) != KING
- ||!pos.can_castle_queenside(us))
- return false;
-
- assert(from == pos.king_square(us));
- assert(to == pos.initial_qr_square(us));
- assert(pos.piece_on(to) == piece_of_color_and_type(us, ROOK));
-
- Square c1 = relative_square(us, SQ_C1);
- Square d1 = relative_square(us, SQ_D1);
- Square s;
- bool illegal = false;
-
- for (s = Min(from, c1); s <= Max(from, c1); s++)
- if( (s != from && s != to && !pos.square_is_empty(s))
- || pos.square_is_attacked(s, them))
- illegal = true;
-
- for (s = Min(to, d1); s <= Max(to, d1); s++)
- if(s != from && s != to && !pos.square_is_empty(s))
- illegal = true;
-
- if ( square_file(to) == FILE_B
- && ( pos.piece_on(to + DELTA_W) == piece_of_color_and_type(them, ROOK)
- || pos.piece_on(to + DELTA_W) == piece_of_color_and_type(them, QUEEN)))
- illegal = true;
-
- return !illegal;
- }
-
- // Normal moves
-
// The destination square cannot be occupied by a friendly piece
if (pos.color_of_piece_on(to) == us)
return false;
- // Proceed according to the type of the moving piece.
+ // Handle the special case of a pawn move
if (type_of_piece(pc) == PAWN)
{
// Move direction must be compatible with pawn color
if ((us == WHITE) != (direction > 0))
return false;
- // If the destination square is on the 8/1th rank, the move must
- // be a promotion.
- if ( ( (square_rank(to) == RANK_8 && us == WHITE)
- ||(square_rank(to) == RANK_1 && us != WHITE))
- && !move_is_promotion(m))
+ // We have already handled promotion moves, so destination
+ // cannot be on the 8/1th rank.
+ if (square_rank(to) == RANK_8 || square_rank(to) == RANK_1)
return false;
- // Proceed according to the square delta between the source and
- // destionation squares.
+ // Proceed according to the square delta between the origin and
+ // destination squares.
switch (direction)
{
case DELTA_NW:
default:
return false;
}
- // The move is pseudo-legal, check if it is also legal
- return pos.pl_move_is_legal(m, pinned);
}
-
- // Luckly we can handle all the other pieces in one go
- return ( pos.piece_attacks_square(pos.piece_on(from), from, to)
- && pos.pl_move_is_legal(m, pinned)
- && !move_is_promotion(m));
-}
-
-
-/// Another version of move_is_legal(), which takes only a position and a move
-/// as input. This function does not require that the side to move is not in
-/// check. It is not optimized for speed, and is only used for verifying move
-/// legality when building a PV from the transposition table.
-
-bool move_is_legal(const Position& pos, const Move m) {
-
- Bitboard pinned = pos.pinned_pieces(pos.side_to_move());
- if (!pos.is_check())
- return move_is_legal(pos, m, pinned);
- else
- {
- Position p(pos);
- MoveStack mlist[64];
- MoveStack* last = generate_evasions(p, mlist, pinned);
- for (MoveStack* cur = mlist; cur != last; cur++)
- if (cur->move == m)
- return true;
-
+ else if (!bit_is_set(pos.attacks_from(pc, from), to))
return false;
- }
+
+ // The move is pseudo-legal, check if it is also legal
+ return pos.is_check() ? pos.pl_move_is_evasion(m, pinned) : pos.pl_move_is_legal(m, pinned);
}
template<PieceType Piece>
MoveStack* generate_piece_moves(const Position& pos, MoveStack* mlist, Color us, Bitboard target) {
- Square from;
Bitboard b;
-
- for (int i = 0, e = pos.piece_count(us, Piece); i < e; i++)
- {
- from = pos.piece_list(us, Piece, i);
- b = pos.piece_attacks<Piece>(from) & target;
- SERIALIZE_MOVES(b);
- }
- return mlist;
- }
-
- template<PieceType Piece>
- MoveStack* generate_piece_moves(const Position& pos, MoveStack* mlist,
- Color us, Bitboard target, Bitboard pinned) {
Square from;
- Bitboard b;
+ const Square* ptr = pos.piece_list_begin(us, Piece);
- for (int i = 0, e = pos.piece_count(us, Piece); i < e; i++)
+ if (*ptr != SQ_NONE)
{
- from = pos.piece_list(us, Piece, i);
- if (pinned && bit_is_set(pinned, from))
- continue;
-
- b = pos.piece_attacks<Piece>(from) & target;
- SERIALIZE_MOVES(b);
+ do {
+ from = *ptr;
+ b = pos.attacks_from<Piece>(from) & target;
+ SERIALIZE_MOVES(b);
+ } while (*++ptr != SQ_NONE);
}
return mlist;
}
Bitboard b;
Square from = pos.king_square(us);
- b = pos.piece_attacks<KING>(from) & target;
+ b = pos.attacks_from<KING>(from) & target;
SERIALIZE_MOVES(b);
return mlist;
}
- template<Color Us, SquareDelta Diagonal>
- MoveStack* generate_pawn_captures_diagonal(MoveStack* mlist, Bitboard pawns, Bitboard enemyPieces, bool promotion) {
+ template<Color Us, SquareDelta Direction>
+ inline Bitboard move_pawns(Bitboard p) {
+
+ if (Direction == DELTA_N)
+ return Us == WHITE ? p << 8 : p >> 8;
+ else if (Direction == DELTA_NE)
+ return Us == WHITE ? p << 9 : p >> 7;
+ else if (Direction == DELTA_NW)
+ return Us == WHITE ? p << 7 : p >> 9;
+ else
+ return p;
+ }
+
+ template<Color Us, MoveType Type, SquareDelta Diagonal>
+ inline MoveStack* generate_pawn_captures(MoveStack* mlist, Bitboard pawns, Bitboard enemyPieces) {
// Calculate our parametrized parameters at compile time
const Bitboard TRank8BB = (Us == WHITE ? Rank8BB : Rank1BB);
const SquareDelta TDELTA_NW = (Us == WHITE ? DELTA_NW : DELTA_SW);
const SquareDelta TTDELTA_NE = (Diagonal == DELTA_NE ? TDELTA_NE : TDELTA_NW);
+ Bitboard b1, b2;
Square to;
// Captures in the a1-h8 (a8-h1 for black) diagonal or in the h1-a8 (h8-a1 for black)
- Bitboard b1 = move_pawns<Us, Diagonal>(pawns) & ~TFileABB & enemyPieces;
+ b1 = move_pawns<Us, Diagonal>(pawns) & ~TFileABB & enemyPieces;
- // Capturing promotions
- if (promotion)
+ // Capturing promotions and under-promotions
+ if (b1 & TRank8BB)
{
- Bitboard b2 = b1 & TRank8BB;
+ b2 = b1 & TRank8BB;
b1 &= ~TRank8BB;
while (b2)
{
to = pop_1st_bit(&b2);
- (*mlist++).move = make_promotion_move(to - TTDELTA_NE, to, QUEEN);
+
+ if (Type == CAPTURE || Type == EVASION)
+ (*mlist++).move = make_promotion_move(to - TTDELTA_NE, to, QUEEN);
+
+ if (Type == NON_CAPTURE || Type == EVASION)
+ {
+ (*mlist++).move = make_promotion_move(to - TTDELTA_NE, to, ROOK);
+ (*mlist++).move = make_promotion_move(to - TTDELTA_NE, to, BISHOP);
+ (*mlist++).move = make_promotion_move(to - TTDELTA_NE, to, KNIGHT);
+ }
+
+ // This is the only possible under promotion that can give a check
+ // not already included in the queen-promotion. It is not sure that
+ // the promoted knight will give check, but it doesn't worth to verify.
+ if (Type == CHECK)
+ (*mlist++).move = make_promotion_move(to - TTDELTA_NE, to, KNIGHT);
}
}
- // Capturing non-promotions
- SERIALIZE_MOVES_D(b1, -TTDELTA_NE);
+ // Serialize standard captures
+ if (Type == CAPTURE || Type == EVASION)
+ SERIALIZE_MOVES_D(b1, -TTDELTA_NE);
+
return mlist;
}
- template<Color Us>
- MoveStack* generate_pawn_captures(const Position& pos, MoveStack* mlist) {
+ template<Color Us, MoveType Type>
+ MoveStack* generate_pawn_moves(const Position& pos, MoveStack* mlist, Bitboard target, Square ksq) {
// Calculate our parametrized parameters at compile time
const Color Them = (Us == WHITE ? BLACK : WHITE);
const Bitboard TRank8BB = (Us == WHITE ? Rank8BB : Rank1BB);
const Bitboard TRank7BB = (Us == WHITE ? Rank7BB : Rank2BB);
+ const Bitboard TRank3BB = (Us == WHITE ? Rank3BB : Rank6BB);
const SquareDelta TDELTA_N = (Us == WHITE ? DELTA_N : DELTA_S);
Square to;
- Bitboard pawns = pos.pawns(Us);
- Bitboard enemyPieces = pos.pieces_of_color(opposite_color(Us));
- bool possiblePromotion = (pawns & TRank7BB);
-
- // Standard captures and capturing promotions in both directions
- mlist = generate_pawn_captures_diagonal<Us, DELTA_NE>(mlist, pawns, enemyPieces, possiblePromotion);
- mlist = generate_pawn_captures_diagonal<Us, DELTA_NW>(mlist, pawns, enemyPieces, possiblePromotion);
+ Bitboard b1, b2, enemyPieces, emptySquares;
+ Bitboard pawns = pos.pieces(PAWN, Us);
- // Non-capturing promotions
- if (possiblePromotion)
+ // Standard captures and capturing promotions and underpromotions
+ if (Type == CAPTURE || Type == EVASION || (pawns & TRank7BB))
{
- Bitboard b1 = move_pawns<Us, DELTA_N>(pawns) & pos.empty_squares() & TRank8BB;
- while (b1)
- {
- to = pop_1st_bit(&b1);
- (*mlist++).move = make_promotion_move(to - TDELTA_N, to, QUEEN);
- }
+ enemyPieces = (Type == CAPTURE ? target : pos.pieces_of_color(opposite_color(Us)));
+
+ if (Type == EVASION)
+ enemyPieces &= target; // Capture only the checker piece
+
+ mlist = generate_pawn_captures<Us, Type, DELTA_NE>(mlist, pawns, enemyPieces);
+ mlist = generate_pawn_captures<Us, Type, DELTA_NW>(mlist, pawns, enemyPieces);
}
- // En passant captures
- if (pos.ep_square() != SQ_NONE)
+ // Non-capturing promotions and underpromotions
+ if (pawns & TRank7BB)
{
- assert(Us != WHITE || square_rank(pos.ep_square()) == RANK_6);
- assert(Us != BLACK || square_rank(pos.ep_square()) == RANK_3);
+ b1 = move_pawns<Us, DELTA_N>(pawns) & TRank8BB & pos.empty_squares();
- Bitboard b1 = pawns & pos.pawn_attacks(Them, pos.ep_square());
- assert(b1 != EmptyBoardBB);
+ if (Type == EVASION)
+ b1 &= target; // Only blocking promotion pushes
while (b1)
{
to = pop_1st_bit(&b1);
- (*mlist++).move = make_ep_move(to, pos.ep_square());
- }
- }
- return mlist;
- }
- template<Color Us>
- MoveStack* generate_pawn_noncaptures(const Position& pos, MoveStack* mlist) {
+ if (Type == CAPTURE || Type == EVASION)
+ (*mlist++).move = make_promotion_move(to - TDELTA_N, to, QUEEN);
- // Calculate our parametrized parameters at compile time
- const Bitboard TRank8BB = (Us == WHITE ? Rank8BB : Rank1BB);
- const Bitboard TRank7BB = (Us == WHITE ? Rank7BB : Rank2BB);
- const Bitboard TRank3BB = (Us == WHITE ? Rank3BB : Rank6BB);
- const SquareDelta TDELTA_NE = (Us == WHITE ? DELTA_NE : DELTA_SE);
- const SquareDelta TDELTA_NW = (Us == WHITE ? DELTA_NW : DELTA_SW);
- const SquareDelta TDELTA_N = (Us == WHITE ? DELTA_N : DELTA_S);
+ if (Type == NON_CAPTURE || Type == EVASION)
+ {
+ (*mlist++).move = make_promotion_move(to - TDELTA_N, to, ROOK);
+ (*mlist++).move = make_promotion_move(to - TDELTA_N, to, BISHOP);
+ (*mlist++).move = make_promotion_move(to - TDELTA_N, to, KNIGHT);
+ }
- Bitboard b1, b2;
- Square to;
- Bitboard pawns = pos.pawns(Us);
- Bitboard emptySquares = pos.empty_squares();
+ // This is the only possible under promotion that can give a check
+ // not already included in the queen-promotion.
+ if (Type == CHECK && bit_is_set(pos.attacks_from<KNIGHT>(to), pos.king_square(Them)))
+ (*mlist++).move = make_promotion_move(to - TDELTA_N, to, KNIGHT);
+ }
+ }
- if (pawns & TRank7BB) // There is some promotion candidate ?
+ // Standard pawn pushes and double pushes
+ if (Type != CAPTURE)
{
- Bitboard enemyPieces = pos.pieces_of_color(opposite_color(Us));
+ emptySquares = (Type == NON_CAPTURE ? target : pos.empty_squares());
- // Underpromotion captures in the a1-h8 (a8-h1 for black) direction
- b1 = move_pawns<Us, DELTA_NE>(pawns) & ~FileABB & enemyPieces & TRank8BB;
- while (b1)
- {
- to = pop_1st_bit(&b1);
- (*mlist++).move = make_promotion_move(to - TDELTA_NE, to, ROOK);
- (*mlist++).move = make_promotion_move(to - TDELTA_NE, to, BISHOP);
- (*mlist++).move = make_promotion_move(to - TDELTA_NE, to, KNIGHT);
- }
+ // Single and double pawn pushes
+ b1 = move_pawns<Us, DELTA_N>(pawns) & emptySquares & ~TRank8BB;
+ b2 = move_pawns<Us, DELTA_N>(b1 & TRank3BB) & emptySquares;
- // Underpromotion captures in the h1-a8 (h8-a1 for black) direction
- b1 = move_pawns<Us, DELTA_NW>(pawns) & ~FileHBB & enemyPieces & TRank8BB;
- while (b1)
+ // Filter out unwanted pushes according to the move type
+ if (Type == EVASION)
{
- to = pop_1st_bit(&b1);
- (*mlist++).move = make_promotion_move(to - TDELTA_NW, to, ROOK);
- (*mlist++).move = make_promotion_move(to - TDELTA_NW, to, BISHOP);
- (*mlist++).move = make_promotion_move(to - TDELTA_NW, to, KNIGHT);
+ b1 &= target;
+ b2 &= target;
}
-
- // Underpromotion pawn pushes
- b1 = move_pawns<Us, DELTA_N>(pawns) & emptySquares & TRank8BB;
- while (b1)
+ else if (Type == CHECK)
{
- to = pop_1st_bit(&b1);
- (*mlist++).move = make_promotion_move(to - TDELTA_N, to, ROOK);
- (*mlist++).move = make_promotion_move(to - TDELTA_N, to, BISHOP);
- (*mlist++).move = make_promotion_move(to - TDELTA_N, to, KNIGHT);
+ // Pawn moves which give direct cheks
+ b1 &= pos.attacks_from<PAWN>(ksq, Them);
+ b2 &= pos.attacks_from<PAWN>(ksq, Them);
+
+ // Pawn moves which gives discovered check. This is possible only if
+ // the pawn is not on the same file as the enemy king, because we
+ // don't generate captures.
+ if (pawns & target) // For CHECK type target is dc bitboard
+ {
+ Bitboard dc1 = move_pawns<Us, DELTA_N>(pawns & target & ~file_bb(ksq)) & emptySquares & ~TRank8BB;
+ Bitboard dc2 = move_pawns<Us, DELTA_N>(dc1 & TRank3BB) & emptySquares;
+
+ b1 |= dc1;
+ b2 |= dc2;
+ }
}
+ SERIALIZE_MOVES_D(b1, -TDELTA_N);
+ SERIALIZE_MOVES_D(b2, -TDELTA_N -TDELTA_N);
}
- // Single pawn pushes
- b2 = b1 = move_pawns<Us, DELTA_N>(pawns) & emptySquares & ~TRank8BB;
- SERIALIZE_MOVES_D(b2, -TDELTA_N);
-
- // Double pawn pushes
- b2 = move_pawns<Us, DELTA_N>(b1 & TRank3BB) & emptySquares;
- SERIALIZE_MOVES_D(b2, -TDELTA_N -TDELTA_N);
- return mlist;
- }
-
-
- template<Color Us>
- MoveStack* generate_pawn_checks(const Position& pos, Bitboard dc, Square ksq, MoveStack* mlist)
- {
- // Calculate our parametrized parameters at compile time
- const Color Them = (Us == WHITE ? BLACK : WHITE);
- const Bitboard TRank8BB = (Us == WHITE ? Rank8BB : Rank1BB);
- const Bitboard TRank3BB = (Us == WHITE ? Rank3BB : Rank6BB);
- const SquareDelta TDELTA_N = (Us == WHITE ? DELTA_N : DELTA_S);
- const SquareDelta TDELTA_S = (Us == WHITE ? DELTA_S : DELTA_N);
-
- Square to;
- Bitboard b1, b2, b3;
- Bitboard pawns = pos.pawns(Us);
-
- if (dc & pawns)
+ // En passant captures
+ if ((Type == CAPTURE || Type == EVASION) && pos.ep_square() != SQ_NONE)
{
- Bitboard empty = pos.empty_squares();
-
- // Pawn moves which gives discovered check. This is possible only if the
- // pawn is not on the same file as the enemy king, because we don't
- // generate captures.
- b1 = pawns & ~file_bb(ksq);
-
- // Discovered checks, single pawn pushes, no promotions
- b2 = b3 = move_pawns<Us, DELTA_N>(b1 & dc) & empty & ~TRank8BB;
- SERIALIZE_MOVES_D(b3, -TDELTA_N);
-
- // Discovered checks, double pawn pushes
- b3 = move_pawns<Us, DELTA_N>(b2 & TRank3BB) & empty;
- SERIALIZE_MOVES_D(b3, -TDELTA_N -TDELTA_N);
- }
+ assert(Us != WHITE || square_rank(pos.ep_square()) == RANK_6);
+ assert(Us != BLACK || square_rank(pos.ep_square()) == RANK_3);
- // Direct checks. These are possible only for pawns on neighboring files
- // and in the two ranks that, after the push, are in front of the enemy king.
- b1 = pawns & neighboring_files_bb(ksq) & ~dc;
+ // An en passant capture can be an evasion only if the checking piece
+ // is the double pushed pawn and so is in the target. Otherwise this
+ // is a discovery check and we are forced to do otherwise.
+ if (Type == EVASION && !bit_is_set(target, pos.ep_square() - TDELTA_N))
+ return mlist;
- // We can get false positives if (ksq + x) is not in [0,63] range but
- // is not a problem, they will be filtered out later.
- b2 = b1 & (rank_bb(ksq + 2 * TDELTA_S) | rank_bb(ksq + 3 * TDELTA_S));
- if (!b2)
- return mlist;
+ b1 = pawns & pos.attacks_from<PAWN>(pos.ep_square(), Them);
- // Direct checks, single pawn pushes
- Bitboard empty = pos.empty_squares();
- b2 = move_pawns<Us, DELTA_N>(b1) & empty;
- b3 = b2 & pos.pawn_attacks(Them, ksq);
- SERIALIZE_MOVES_D(b3, -TDELTA_N);
+ assert(b1 != EmptyBoardBB);
- // Direct checks, double pawn pushes
- b3 = move_pawns<Us, DELTA_N>(b2 & TRank3BB) & empty & pos.pawn_attacks(Them, ksq);
- SERIALIZE_MOVES_D(b3, -TDELTA_N -TDELTA_N);
+ while (b1)
+ {
+ to = pop_1st_bit(&b1);
+ (*mlist++).move = make_ep_move(to, pos.ep_square());
+ }
+ }
return mlist;
}
template<PieceType Piece>
- MoveStack* generate_piece_checks(const Position& pos, MoveStack* mlist, Color us,
- Bitboard dc, Square ksq) {
-
- Bitboard target = pos.pieces_of_color(us) & pos.pieces_of_type(Piece);
-
- // Discovered checks
- Bitboard b = target & dc;
- while (b)
- {
- Square from = pop_1st_bit(&b);
- Bitboard bb = pos.piece_attacks<Piece>(from) & pos.empty_squares();
- if (Piece == KING)
- bb &= ~QueenPseudoAttacks[ksq];
+ MoveStack* generate_discovered_checks(const Position& pos, MoveStack* mlist, Square from) {
- SERIALIZE_MOVES(bb);
- }
+ assert(Piece != QUEEN);
- // Direct checks
- b = target & ~dc;
- if (Piece != KING || b)
+ Bitboard b = pos.attacks_from<Piece>(from) & pos.empty_squares();
+ if (Piece == KING)
{
- Bitboard checkSqs = pos.piece_attacks<Piece>(ksq) & pos.empty_squares();
- if (!checkSqs)
- return mlist;
-
- while (b)
- {
- Square from = pop_1st_bit(&b);
- if ( (Piece == QUEEN && !(QueenPseudoAttacks[from] & checkSqs))
- || (Piece == ROOK && !(RookPseudoAttacks[from] & checkSqs))
- || (Piece == BISHOP && !(BishopPseudoAttacks[from] & checkSqs)))
- continue;
-
- Bitboard bb = pos.piece_attacks<Piece>(from) & checkSqs;
- SERIALIZE_MOVES(bb);
- }
+ Square ksq = pos.king_square(opposite_color(pos.side_to_move()));
+ b &= ~QueenPseudoAttacks[ksq];
}
+ SERIALIZE_MOVES(b);
return mlist;
}
- template<Color Us>
- MoveStack* generate_pawn_blocking_evasions(const Position& pos, Bitboard pinned,
- Bitboard blockSquares, MoveStack* mlist) {
+ template<PieceType Piece>
+ MoveStack* generate_direct_checks(const Position& pos, MoveStack* mlist, Color us,
+ Bitboard dc, Square ksq) {
+ assert(Piece != KING);
- // Calculate our parametrized parameters at compile time
- const Rank TRANK_8 = (Us == WHITE ? RANK_8 : RANK_1);
- const Bitboard TRank3BB = (Us == WHITE ? Rank3BB : Rank6BB);
- const SquareDelta TDELTA_N = (Us == WHITE ? DELTA_N : DELTA_S);
+ Bitboard checkSqs, b;
+ Square from;
+ const Square* ptr = pos.piece_list_begin(us, Piece);
- Square to;
+ if ((from = *ptr++) == SQ_NONE)
+ return mlist;
- // Find non-pinned pawns and push them one square
- Bitboard b1 = move_pawns<Us, DELTA_N>(pos.pawns(Us) & ~pinned);
+ checkSqs = pos.attacks_from<Piece>(ksq) & pos.empty_squares();
- // We don't have to AND with empty squares here,
- // because the blocking squares will always be empty.
- Bitboard b2 = b1 & blockSquares;
- while (b2)
+ do
{
- to = pop_1st_bit(&b2);
-
- assert(pos.piece_on(to) == EMPTY);
+ if ( (Piece == QUEEN && !(QueenPseudoAttacks[from] & checkSqs))
+ || (Piece == ROOK && !(RookPseudoAttacks[from] & checkSqs))
+ || (Piece == BISHOP && !(BishopPseudoAttacks[from] & checkSqs)))
+ continue;
- if (square_rank(to) == TRANK_8)
- {
- (*mlist++).move = make_promotion_move(to - TDELTA_N, to, QUEEN);
- (*mlist++).move = make_promotion_move(to - TDELTA_N, to, ROOK);
- (*mlist++).move = make_promotion_move(to - TDELTA_N, to, BISHOP);
- (*mlist++).move = make_promotion_move(to - TDELTA_N, to, KNIGHT);
- } else
- (*mlist++).move = make_move(to - TDELTA_N, to);
- }
+ if (dc && bit_is_set(dc, from))
+ continue;
- // Double pawn pushes
- b2 = b1 & pos.empty_squares() & TRank3BB;
- b2 = move_pawns<Us, DELTA_N>(b2) & blockSquares;
- while (b2)
- {
- to = pop_1st_bit(&b2);
+ b = pos.attacks_from<Piece>(from) & checkSqs;
+ SERIALIZE_MOVES(b);
- assert(pos.piece_on(to) == EMPTY);
- assert(Us != WHITE || square_rank(to) == RANK_4);
- assert(Us != BLACK || square_rank(to) == RANK_5);
+ } while ((from = *ptr++) != SQ_NONE);
- (*mlist++).move = make_move(to - TDELTA_N - TDELTA_N, to);
- }
return mlist;
}
// It is a bit complicated to correctly handle Chess960
for (s = Min(ksq, s1); s <= Max(ksq, s1); s++)
if ( (s != ksq && s != rsq && pos.square_is_occupied(s))
- || pos.square_is_attacked(s, them))
+ ||(pos.attackers_to(s) & pos.pieces_of_color(them)))
illegal = true;
for (s = Min(rsq, s2); s <= Max(rsq, s2); s++)
}
return mlist;
}
-
- bool castling_is_check(const Position& pos, CastlingSide side) {
-
- // After castling opponent king is attacked by the castled rook?
- File rookFile = (side == QUEEN_SIDE ? FILE_D : FILE_F);
- Color us = pos.side_to_move();
- Square ksq = pos.king_square(us);
- Bitboard occ = pos.occupied_squares();
-
- clear_bit(&occ, ksq); // Remove our king from the board
- Square rsq = make_square(rookFile, square_rank(ksq));
- return bit_is_set(rook_attacks_bb(rsq, occ), pos.king_square(opposite_color(us)));
- }
}
projects / stockfish / blobdiff