namespace {
+ enum CastlingSide {
+ KING_SIDE,
+ QUEEN_SIDE
+ };
+
// Function
+ bool castling_is_check(const Position&, CastlingSide);
+
+ // Template
+ template<CastlingSide Side>
MoveStack* generate_castle_moves(const Position&, MoveStack*);
// Template generate_pawn_captures() with specializations
Bitboard target = pos.pieces_of_color(opposite_color(us));
MoveStack* mlist_start = mlist;
+ mlist = generate_piece_moves<QUEEN>(pos, mlist, us, target);
+ 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);
+
if (us == WHITE)
mlist = generate_pawn_captures<WHITE>(pos, mlist);
else
mlist = generate_pawn_captures<BLACK>(pos, mlist);
- 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);
return int(mlist - mlist_start);
}
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(pos, mlist);
+ mlist = generate_castle_moves<KING_SIDE>(pos, mlist);
+ mlist = generate_castle_moves<QUEEN_SIDE>(pos, mlist);
return int(mlist - mlist_start);
}
/// generate_checks() generates all pseudo-legal non-capturing, non-promoting
-/// checks, except castling moves (will add this later). It returns the
-/// number of generated moves.
+/// checks. It returns the number of generated moves.
int generate_checks(const Position& pos, MoveStack* mlist, Bitboard dc) {
// Hopefully we always have a king ;-)
mlist = generate_piece_checks_king(pos, pos.king_square(us), dc, ksq, mlist);
- // TODO: Castling moves!
+ // 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 int(mlist - mlist_start);
}
/// 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. This
+/// only legal moves. It returns the number of generated moves. This
/// function is very ugly, and needs cleaning up some time later. FIXME
int generate_evasions(const Position& pos, MoveStack* mlist) {
// Pawn moves. Because a blocking evasion can never be a capture, we
// only generate pawn pushes.
if (us == WHITE)
- generate_pawn_blocking_evasions<WHITE>(pos, not_pinned, blockSquares, mlist);
+ mlist = generate_pawn_blocking_evasions<WHITE>(pos, not_pinned, blockSquares, mlist);
else
- generate_pawn_blocking_evasions<BLACK>(pos, not_pinned, blockSquares, mlist);
+ mlist = generate_pawn_blocking_evasions<BLACK>(pos, not_pinned, blockSquares, mlist);
// Pieces moves
b1 = pos.knights(us) & not_pinned;
if (b1)
- generate_piece_blocking_evasions<KNIGHT>(pos, b1, blockSquares, mlist);
+ mlist = generate_piece_blocking_evasions<KNIGHT>(pos, b1, blockSquares, mlist);
b1 = pos.bishops(us) & not_pinned;
if (b1)
- generate_piece_blocking_evasions<BISHOP>(pos, b1, blockSquares, mlist);
+ mlist = generate_piece_blocking_evasions<BISHOP>(pos, b1, blockSquares, mlist);
b1 = pos.rooks(us) & not_pinned;
if (b1)
- generate_piece_blocking_evasions<ROOK>(pos, b1, blockSquares, mlist);
+ mlist = generate_piece_blocking_evasions<ROOK>(pos, b1, blockSquares, mlist);
b1 = pos.queens(us) & not_pinned;
if (b1)
- generate_piece_blocking_evasions<QUEEN>(pos, b1, blockSquares, mlist);
+ mlist = generate_piece_blocking_evasions<QUEEN>(pos, b1, blockSquares, mlist);
}
// Finally, the ugly special case of en passant captures. An en passant
/// 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
+/// 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.
// Remove illegal moves from the list
for (int i = 0; i < n; i++)
- if (!pos.move_is_legal(mlist[i].move, pinned))
+ if (!pos.pl_move_is_legal(mlist[i].move, pinned))
mlist[i--].move = mlist[--n].move;
return n;
}
-/// generate_move_if_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 MOVE_NONE. This function must
+/// 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 generate_move_if_legal(const Position& pos, Move m, Bitboard pinned) {
+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);
// 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 MOVE_NONE;
+ return false;
Square to = move_to(m);
// en passant square.
if ( type_of_piece(pc) != PAWN
|| to != pos.ep_square())
- return MOVE_NONE;
+ return false;
assert(pos.square_is_empty(to));
assert(pos.piece_on(to - pawn_push(us)) == pawn_of_color(them));
- // The move is pseudo-legal. If it is legal, return it.
- return (pos.move_is_legal(m) ? m : MOVE_NONE);
+ // The move is pseudo-legal, check if it is also legal
+ return pos.pl_move_is_legal(m, pinned);
}
// Castling moves
// the right to castle kingside.
if ( type_of_piece(pc) != KING
||!pos.can_castle_kingside(us))
- return MOVE_NONE;
+ return false;
assert(from == pos.king_square(us));
assert(to == pos.initial_kr_square(us));
if (s != from && s != to && !pos.square_is_empty(s))
illegal = true;
- return (!illegal ? m : MOVE_NONE);
+ return !illegal;
}
if (move_is_long_castle(m))
// the right to castle kingside.
if ( type_of_piece(pc) != KING
||!pos.can_castle_queenside(us))
- return MOVE_NONE;
+ return false;
assert(from == pos.king_square(us));
assert(to == pos.initial_qr_square(us));
|| pos.piece_on(to + DELTA_W) == queen_of_color(them)))
illegal = true;
- return (!illegal ? m : MOVE_NONE);
+ return !illegal;
}
// Normal moves
// The destination square cannot be occupied by a friendly piece
if (pos.color_of_piece_on(to) == us)
- return MOVE_NONE;
+ return false;
// Proceed according to the type of the moving piece.
if (type_of_piece(pc) == PAWN)
if ( ( (square_rank(to) == RANK_8 && us == WHITE)
||(square_rank(to) == RANK_1 && us != WHITE))
&& !move_promotion(m))
- return MOVE_NONE;
+ return false;
// Proceed according to the square delta between the source and
// destionation squares.
// Capture. The destination square must be occupied by an enemy
// piece (en passant captures was handled earlier).
if (pos.color_of_piece_on(to) != them)
- return MOVE_NONE;
+ return false;
break;
case DELTA_N:
case DELTA_S:
// Pawn push. The destination square must be empty.
if (!pos.square_is_empty(to))
- return MOVE_NONE;
+ return false;
break;
case DELTA_NN:
if ( square_rank(to) != RANK_4
|| !pos.square_is_empty(to)
|| !pos.square_is_empty(from + DELTA_N))
- return MOVE_NONE;
+ return false;
break;
case DELTA_SS:
if ( square_rank(to) != RANK_5
|| !pos.square_is_empty(to)
|| !pos.square_is_empty(from + DELTA_S))
- return MOVE_NONE;
+ return false;
break;
default:
- return MOVE_NONE;
+ return false;
}
- // The move is pseudo-legal. Return it if it is legal.
- return (pos.move_is_legal(m) ? m : MOVE_NONE);
+ // 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(from, to)
- && pos.move_is_legal(m)
- && !move_promotion(m) ? m : MOVE_NONE);
+ && pos.pl_move_is_legal(m, pinned)
+ && !move_promotion(m));
}
template<Color Us, Color Them, Bitboard TRank8BB, SquareDelta TDELTA_NE,
SquareDelta TDELTA_NW, SquareDelta TDELTA_N
>
- MoveStack* do_generate_pawn_captures(const Position& pos, MoveStack* mlist) {
+ MoveStack* do_generate_pawn_captures(const Position& pos, MoveStack* mlist) {
Square to;
Bitboard pawns = pos.pawns(Us);
template<Color Us, Color Them, Bitboard TRank8BB, Bitboard TRank3BB,
SquareDelta TDELTA_NE, SquareDelta TDELTA_NW, SquareDelta TDELTA_N
>
- MoveStack* do_generate_pawn_noncaptures(const Position& pos, MoveStack* mlist) {
+ MoveStack* do_generate_pawn_noncaptures(const Position& pos, MoveStack* mlist) {
Bitboard pawns = pos.pawns(Us);
Bitboard enemyPieces = pos.pieces_of_color(Them);
b2 = b1 & TRank8BB;
while (b2)
{
- to = pop_1st_bit(&b2);
- (*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);
+ to = pop_1st_bit(&b2);
+ (*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);
}
b2 = b1 & ~TRank8BB;
while (b2)
b2 = (Us == WHITE ? (b1 & TRank3BB) << 8 : (b1 & TRank3BB) >> 8) & emptySquares;
while (b2)
{
- to = pop_1st_bit(&b2);
- (*mlist++).move = make_move(to - TDELTA_N - TDELTA_N, to);
+ to = pop_1st_bit(&b2);
+ (*mlist++).move = make_move(to - TDELTA_N - TDELTA_N, to);
}
return mlist;
}
// Find all friendly pawns not on the enemy king's file
Bitboard b1 = pos.pawns(Us) & ~file_bb(ksq), b2, b3;
- // Discovered checks, single pawn pushes
- b2 = b3 = (Us == WHITE ? (b1 & dc) << 8 : (b1 & dc) >> 8) & ~TRank8BB & empty;
+ // Discovered checks, single pawn pushes, no promotions
+ b2 = b3 = (Us == WHITE ? (b1 & dc) << 8 : (b1 & dc) >> 8) & empty & ~TRank8BB;
while (b3)
{
Square to = pop_1st_bit(&b3);
// Direct checks. These are possible only for pawns on neighboring files
// of the enemy king
-
- b1 &= (~dc & neighboring_files_bb(ksq)); // FIXME why ~dc ??
+ b1 &= (~dc & neighboring_files_bb(ksq));
// Direct checks, single pawn pushes
b2 = (Us == WHITE ? b1 << 8 : b1 >> 8) & empty;
return mlist;
}
-
+ template<CastlingSide Side>
MoveStack* generate_castle_moves(const Position& pos, MoveStack* mlist) {
Color us = pos.side_to_move();
- if (pos.can_castle(us))
+ if ( (Side == KING_SIDE && pos.can_castle_kingside(us))
+ ||(Side == QUEEN_SIDE && pos.can_castle_queenside(us)))
{
Color them = opposite_color(us);
Square ksq = pos.king_square(us);
assert(pos.piece_on(ksq) == king_of_color(us));
- if (pos.can_castle_kingside(us))
- {
- Square rsq = pos.initial_kr_square(us);
- Square g1 = relative_square(us, SQ_G1);
- Square f1 = relative_square(us, SQ_F1);
- Square s;
- bool illegal = false;
-
- assert(pos.piece_on(rsq) == rook_of_color(us));
+ Square rsq = (Side == KING_SIDE ? pos.initial_kr_square(us) : pos.initial_qr_square(us));
+ Square s1 = relative_square(us, Side == KING_SIDE ? SQ_G1 : SQ_C1);
+ Square s2 = relative_square(us, Side == KING_SIDE ? SQ_F1 : SQ_D1);
+ Square s;
+ bool illegal = false;
- for (s = Min(ksq, g1); s <= Max(ksq, g1); s++)
- if ( (s != ksq && s != rsq && pos.square_is_occupied(s))
- || pos.square_is_attacked(s, them))
- illegal = true;
+ assert(pos.piece_on(rsq) == rook_of_color(us));
- for (s = Min(rsq, f1); s <= Max(rsq, f1); s++)
- if (s != ksq && s != rsq && pos.square_is_occupied(s))
- illegal = true;
-
- if (!illegal)
- (*mlist++).move = make_castle_move(ksq, rsq);
- }
-
- if (pos.can_castle_queenside(us))
- {
- Square rsq = pos.initial_qr_square(us);
- Square c1 = relative_square(us, SQ_C1);
- Square d1 = relative_square(us, SQ_D1);
- Square s;
- bool illegal = false;
+ // 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))
+ illegal = true;
- assert(pos.piece_on(rsq) == rook_of_color(us));
+ for (s = Min(rsq, s2); s <= Max(rsq, s2); s++)
+ if (s != ksq && s != rsq && pos.square_is_occupied(s))
+ illegal = true;
- for (s = Min(ksq, c1); s <= Max(ksq, c1); s++)
- if ( (s != ksq && s != rsq && pos.square_is_occupied(s))
- || pos.square_is_attacked(s, them))
- illegal = true;
-
- for (s = Min(rsq, d1); s <= Max(rsq, d1); s++)
- if (s != ksq && s != rsq && pos.square_is_occupied(s))
- illegal = true;
-
- if ( square_file(rsq) == FILE_B
+ if ( Side == QUEEN_SIDE
+ && square_file(rsq) == FILE_B
&& ( pos.piece_on(relative_square(us, SQ_A1)) == rook_of_color(them)
|| pos.piece_on(relative_square(us, SQ_A1)) == queen_of_color(them)))
illegal = true;
if (!illegal)
(*mlist++).move = make_castle_move(ksq, rsq);
- }
}
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(), oppKingBB = EmptyBoardBB;
+
+ set_bit(&oppKingBB, pos.king_square(opposite_color(us)));
+ clear_bit(&occ, ksq); // Remove our king from the board
+ Square rsq = make_square(rookFile, square_rank(ksq));
+ return (rook_attacks_bb(rsq, occ) & oppKingBB);
+ }
}
projects / stockfish / blobdiff