X-Git-Url: https://git.sesse.net/?p=stockfish;a=blobdiff_plain;f=src%2Fmovegen.cpp;h=37e66724e5decd81e25a8eaecd552264f200e2c1;hp=50f8b4887ff0f7887378565abca3c674565f50d3;hb=1b0fee9b17a1220b60b3051626e8444f474e884c;hpb=5dc23121215039938a9ef4e59ae934312774571c diff --git a/src/movegen.cpp b/src/movegen.cpp index 50f8b488..37e66724 100644 --- a/src/movegen.cpp +++ b/src/movegen.cpp @@ -6,12 +6,12 @@ it under the terms of the GNU General Public License as published by the Free Software Foundation, either version 3 of the License, or (at your option) any later version. - + Stockfish is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details. - + You should have received a copy of the GNU General Public License along with this program. If not, see . */ @@ -25,6 +25,9 @@ #include "movegen.h" +// Simple macro to wrap a very common while loop, no facny, no flexibility, +// hardcoded list name 'mlist' and from square 'from'. +#define SERIALIZE_MOVES(b) while (b) (*mlist++).move = make_move(from, pop_1st_bit(&b)) //// //// Local definitions @@ -32,88 +35,79 @@ namespace { - struct PawnParams { - Bitboard Rank3BB, Rank8BB; - Rank RANK_8; - SquareDelta DELTA_N, DELTA_NE, DELTA_NW; - Color us, them; + enum CastlingSide { + KING_SIDE, + QUEEN_SIDE }; - const PawnParams WhitePawnParams = { Rank3BB, Rank8BB, RANK_8, DELTA_N, DELTA_NE, DELTA_NW, WHITE, BLACK }; - const PawnParams BlackPawnParams = { Rank6BB, Rank1BB, RANK_1, DELTA_S, DELTA_SE, DELTA_SW, BLACK, WHITE }; - - int generate_castle_moves(const Position&, MoveStack*, Color); - template - int generate_pawn_captures(const Position&, MoveStack*); + enum MoveType { + CAPTURE, + NON_CAPTURE + }; - template - int generate_pawn_noncaptures(const Position&, MoveStack*); - - template - int generate_pawn_checks(const Position&, Bitboard, Square, MoveStack*, int); + // Functions + bool castling_is_check(const Position&, CastlingSide); - template - int generate_pawn_blocking_evasions(const Position&, Bitboard, Bitboard, MoveStack*, int); + // Helper templates + template + MoveStack* generate_castle_moves(const Position& pos, MoveStack* mlist); - template - int generate_piece_moves(const Position&, MoveStack*, Color, Bitboard); + template + MoveStack* generate_pawn_blocking_evasions(const Position&, Bitboard, Bitboard, MoveStack*); - template - int generate_piece_checks(const Position&, Bitboard, Bitboard, Square, MoveStack*, int); + template + MoveStack* generate_pawn_captures(const Position& pos, MoveStack* mlist); + template + MoveStack* generate_pawn_noncaptures(const Position& pos, MoveStack* mlist); + + template + MoveStack* generate_pawn_checks(const Position&, Bitboard, Square, MoveStack*); + + // Template generate_piece_checks() with specializations template - int generate_piece_blocking_evasions(const Position&, Bitboard, Bitboard, MoveStack*, int); + MoveStack* generate_piece_checks(const Position&, MoveStack*, Color, Bitboard, Square); + template<> + inline MoveStack* generate_piece_checks(const Position& p, MoveStack* m, Color us, Bitboard dc, Square ksq) { - /// Templates with specializations are defined here to avoid lookup issues + if (us == WHITE) + return generate_pawn_checks(p, dc, ksq, m); + else + return generate_pawn_checks(p, dc, ksq, m); - template - int generate_piece_checks(const Position& pos, Bitboard target, Bitboard dc, - Square ksq, MoveStack* mlist, int n) { - // Discovered checks - Bitboard b = target & dc; - while (b) - { - Square from = pop_1st_bit(&b); - Bitboard bb = pos.piece_attacks(from) & pos.empty_squares(); - while (bb) - { - Square to = pop_1st_bit(&bb); - mlist[n++].move = make_move(from, to); - } - } - // Direct checks - b = target & ~dc; - Bitboard checkSqs = pos.piece_attacks(ksq) & pos.empty_squares(); - while (b) - { - Square from = pop_1st_bit(&b); - Bitboard bb = pos.piece_attacks(from) & checkSqs; - while (bb) - { - Square to = pop_1st_bit(&bb); - mlist[n++].move = make_move(from, to); - } - } - return n; } + // Template generate_piece_moves() with specializations and overloads + template + MoveStack* generate_piece_moves(const Position&, MoveStack*, Color us, Bitboard); + + template<> + MoveStack* generate_piece_moves(const Position&, MoveStack*, Color, Bitboard); - template<> // Special case the King - int generate_piece_checks(const Position& pos, Bitboard, Bitboard dc, - Square ksq, MoveStack* mlist, int n) { - if (bit_is_set(dc, ksq)) - { - Bitboard bb = pos.piece_attacks(ksq) - & pos.empty_squares() - & ~QueenPseudoAttacks[ksq]; - while (bb) - { - Square to = pop_1st_bit(&bb); - mlist[n++].move = make_move(ksq, to); - } - } - return n; + template + inline MoveStack* generate_piece_moves(const Position& p, MoveStack* m, Color us) { + + assert(Piece == PAWN); + + if (Type == CAPTURE) + return (us == WHITE ? generate_pawn_captures(p, m) + : generate_pawn_captures(p, m)); + else + return (us == WHITE ? generate_pawn_noncaptures(p, m) + : generate_pawn_noncaptures(p, m)); + } + + template + MoveStack* generate_piece_moves(const Position&, MoveStack*, Color us, Bitboard, Bitboard); + + template<> + inline MoveStack* generate_piece_moves(const Position& p, MoveStack* m, + Color us, Bitboard t, Bitboard pnd) { + if (us == WHITE) + return generate_pawn_blocking_evasions(p, pnd, t, m); + else + return generate_pawn_blocking_evasions(p, pnd, t, m); } } @@ -133,254 +127,221 @@ int generate_captures(const Position& pos, MoveStack* mlist) { Color us = pos.side_to_move(); Bitboard target = pos.pieces_of_color(opposite_color(us)); - int n; - - if (us == WHITE) - n = generate_pawn_captures(pos, mlist); - else - n = generate_pawn_captures(pos, mlist); - - n += generate_piece_moves(pos, mlist+n, us, target); - n += generate_piece_moves(pos, mlist+n, us, target); - n += generate_piece_moves(pos, mlist+n, us, target); - n += generate_piece_moves(pos, mlist+n, us, target); - n += generate_piece_moves(pos, mlist+n, us, target); - return n; + MoveStack* mlist_start = mlist; + + mlist = generate_piece_moves(pos, mlist, us, target); + mlist = generate_piece_moves(pos, mlist, us, target); + mlist = generate_piece_moves(pos, mlist, us, target); + mlist = generate_piece_moves(pos, mlist, us, target); + mlist = generate_piece_moves(pos, mlist, us); + mlist = generate_piece_moves(pos, mlist, us, target); + return int(mlist - mlist_start); } -/// generate_noncaptures() generates all pseudo-legal non-captures and -/// underpromotions. The return value is the number of moves generated. +/// generate_noncaptures() generates all pseudo-legal non-captures and +/// underpromotions. The return value is the number of moves generated. -int generate_noncaptures(const Position& pos, MoveStack *mlist) { +int generate_noncaptures(const Position& pos, MoveStack* mlist) { assert(pos.is_ok()); assert(!pos.is_check()); Color us = pos.side_to_move(); Bitboard target = pos.empty_squares(); - int n; - - if (us == WHITE) - n = generate_pawn_noncaptures(pos, mlist); - else - n = generate_pawn_noncaptures(pos, mlist); - - n += generate_piece_moves(pos, mlist+n, us, target); - n += generate_piece_moves(pos, mlist+n, us, target); - n += generate_piece_moves(pos, mlist+n, us, target); - n += generate_piece_moves(pos, mlist+n, us, target); - n += generate_piece_moves(pos, mlist+n, us, target); - - n += generate_castle_moves(pos, mlist+n, us); - return n; + MoveStack* mlist_start = mlist; + + mlist = generate_piece_moves(pos, mlist, us); + mlist = generate_piece_moves(pos, mlist, us, target); + mlist = generate_piece_moves(pos, mlist, us, target); + mlist = generate_piece_moves(pos, mlist, us, target); + mlist = generate_piece_moves(pos, mlist, us, target); + mlist = generate_piece_moves(pos, mlist, us, target); + mlist = generate_castle_moves(pos, mlist); + mlist = generate_castle_moves(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) { +int generate_checks(const Position& pos, MoveStack* mlist) { assert(pos.is_ok()); assert(!pos.is_check()); - int n; Color us = pos.side_to_move(); Square ksq = pos.king_square(opposite_color(us)); + Bitboard dc = pos.discovered_check_candidates(us); + MoveStack* mlist_start = mlist; - assert(pos.piece_on(ksq) == king_of_color(opposite_color(us))); - - dc = pos.discovered_check_candidates(us); - - // Pawn moves - if (us == WHITE) - n = generate_pawn_checks(pos, dc, ksq, mlist, 0); - else - n = generate_pawn_checks(pos, dc, ksq, mlist, 0); + assert(pos.piece_on(ksq) == piece_of_color_and_type(opposite_color(us), KING)); // Pieces moves - Bitboard b = pos.knights(us); - if (b) - n = generate_piece_checks(pos, b, dc, ksq, mlist, n); - - b = pos.bishops(us); - if (b) - n = generate_piece_checks(pos, b, dc, ksq, mlist, n); - - b = pos.rooks(us); - if (b) - n = generate_piece_checks(pos, b, dc, ksq, mlist, n); - - b = pos.queens(us); - if (b) - n = generate_piece_checks(pos, b, dc, ksq, mlist, n); - - // Hopefully we always have a king ;-) - n = generate_piece_checks(pos, b, dc, pos.king_square(us), mlist, n); - - // TODO: Castling moves! - - return n; + mlist = generate_piece_checks(pos, mlist, us, dc, ksq); + mlist = generate_piece_checks(pos, mlist, us, dc, ksq); + mlist = generate_piece_checks(pos, mlist, us, dc, ksq); + mlist = generate_piece_checks(pos, mlist, us, dc, ksq); + mlist = generate_piece_checks(pos, mlist, us, dc, ksq); + mlist = generate_piece_checks(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(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(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 -/// function is very ugly, and needs cleaning up some time later. FIXME +/// in check. Unlike the other move generation functions, this one generates +/// only legal moves. It returns the number of generated moves. int generate_evasions(const Position& pos, MoveStack* mlist) { assert(pos.is_ok()); assert(pos.is_check()); + Square from, to; Color us = pos.side_to_move(); Color them = opposite_color(us); Square ksq = pos.king_square(us); - Square from, to; - int n = 0; + MoveStack* mlist_start = mlist; - assert(pos.piece_on(ksq) == king_of_color(us)); - - // Generate evasions for king - Bitboard b1 = pos.piece_attacks(ksq) & ~pos.pieces_of_color(us); - Bitboard b2 = pos.occupied_squares(); - clear_bit(&b2, ksq); + assert(pos.piece_on(ksq) == piece_of_color_and_type(us, KING)); + + // The bitboard of occupied pieces without our king + Bitboard b_noKing = pos.occupied_squares(); + clear_bit(&b_noKing, ksq); + // 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); + } + + b = checkers & (pos.queens() | pos.rooks()); + while (b) + { + from = pop_1st_bit(&b); + checkersAttacks |= rook_attacks_bb(from, b_noKing); + } + + // Generate evasions for king + Bitboard b1 = pos.piece_attacks(ksq) & ~pos.pieces_of_color(us) & ~checkersAttacks; while (b1) { - Square to = pop_1st_bit(&b1); - - // Make sure to is not attacked by the other side. This is a bit ugly, - // because we can't use Position::square_is_attacked. Instead we use - // the low-level bishop_attacks_bb and rook_attacks_bb with the bitboard - // b2 (the occupied squares with the king removed) in order to test whether - // the king will remain in check on the destination square. - if (!( (bishop_attacks_bb(to, b2) & pos.bishops_and_queens(them)) - || (rook_attacks_bb(to, b2) & pos.rooks_and_queens(them)) - || (pos.piece_attacks(to) & pos.knights(them)) - || (pos.pawn_attacks(us, to) & pos.pawns(them)) - || (pos.piece_attacks(to) & pos.kings(them)))) - - mlist[n++].move = make_move(ksq, to); + 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). - Bitboard checkers = pos.checkers(); - if (!(checkers & (checkers - 1))) // Only one bit set? { Square checksq = first_1(checkers); + Bitboard pinned = pos.pinned_pieces(us); assert(pos.color_of_piece_on(checksq) == them); - // Find pinned pieces - Bitboard not_pinned = ~pos.pinned_pieces(us); - // Generate captures of the checking piece // Pawn captures - b1 = pos.pawn_attacks(them, checksq) & pos.pawns(us) & not_pinned; + 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[n++].move = make_promotion_move(from, checksq, QUEEN); - mlist[n++].move = make_promotion_move(from, checksq, ROOK); - mlist[n++].move = make_promotion_move(from, checksq, BISHOP); - mlist[n++].move = make_promotion_move(from, checksq, KNIGHT); + (*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[n++].move = make_move(from, checksq); + (*mlist++).move = make_move(from, checksq); } // Pieces captures b1 = ( (pos.piece_attacks(checksq) & pos.knights(us)) | (pos.piece_attacks(checksq) & pos.bishops_and_queens(us)) - | (pos.piece_attacks(checksq) & pos.rooks_and_queens(us)) ) & not_pinned; + | (pos.piece_attacks(checksq) & pos.rooks_and_queens(us)) ) & ~pinned; while (b1) { from = pop_1st_bit(&b1); - mlist[n++].move = make_move(from, checksq); + (*mlist++).move = make_move(from, checksq); } // Blocking check evasions are possible only if the checking piece is - // a slider + // a slider. if (checkers & pos.sliders()) { Bitboard blockSquares = squares_between(checksq, ksq); assert((pos.occupied_squares() & blockSquares) == EmptyBoardBB); - // Pawn moves. Because a blocking evasion can never be a capture, we - // only generate pawn pushes. - if (us == WHITE) - n = generate_pawn_blocking_evasions(pos, not_pinned, blockSquares, mlist, n); - else - n = generate_pawn_blocking_evasions(pos, not_pinned, blockSquares, mlist, n); - - // Pieces moves - b1 = pos.knights(us) & not_pinned; - if (b1) - n = generate_piece_blocking_evasions(pos, b1, blockSquares, mlist, n); - - b1 = pos.bishops(us) & not_pinned; - if (b1) - n = generate_piece_blocking_evasions(pos, b1, blockSquares, mlist, n); - - b1 = pos.rooks(us) & not_pinned; - if (b1) - n = generate_piece_blocking_evasions(pos, b1, blockSquares, mlist, n); - - b1 = pos.queens(us) & not_pinned; - if (b1) - n = generate_piece_blocking_evasions(pos, b1, blockSquares, mlist, n); - } + if (blockSquares != EmptyBoardBB) + { + mlist = generate_piece_moves(pos, mlist, us, blockSquares, pinned); + mlist = generate_piece_moves(pos, mlist, us, blockSquares, pinned); + mlist = generate_piece_moves(pos, mlist, us, blockSquares, pinned); + mlist = generate_piece_moves(pos, mlist, us, blockSquares, pinned); + mlist = generate_piece_moves(pos, mlist, us, blockSquares, pinned); + } + } - // Finally, the ugly 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))) - { - to = pos.ep_square(); - b1 = pos.pawn_attacks(them, to) & pos.pawns(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))) + { + to = pos.ep_square(); + b1 = pos.pawn_attacks(them, to) & pos.pawns(us); - assert(b1 != EmptyBoardBB); - - b1 &= not_pinned; - while (b1) - { - from = pop_1st_bit(&b1); - - // Before generating the move, we have to make sure it is legal. - // This is somewhat tricky, because the two disappearing pawns may - // cause new "discovered checks". We test this by removing the - // two relevant bits from the occupied squares bitboard, and using - // the low-level bitboard functions for bishop and rook attacks. - b2 = pos.occupied_squares(); - clear_bit(&b2, from); - clear_bit(&b2, checksq); - if (!( (bishop_attacks_bb(ksq, b2) & pos.bishops_and_queens(them)) - ||(rook_attacks_bb(ksq, b2) & pos.rooks_and_queens(them)))) - - mlist[n++].move = make_ep_move(from, to); - } - } + // 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); + } + } } - return n; + return int(mlist - mlist_start); } /// 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. @@ -391,28 +352,26 @@ int generate_legal_moves(const Position& pos, MoveStack* mlist) { if (pos.is_check()) return generate_evasions(pos, mlist); - // Generate pseudo-legal moves: + // Generate pseudo-legal moves int n = generate_captures(pos, mlist); n += generate_noncaptures(pos, mlist + n); - Bitboard pinned = pos.pinned_pieces(pos.side_to_move()); - - // Remove illegal moves from the list: + // 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)) 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) { assert(pos.is_ok()); assert(!pos.is_check()); @@ -426,7 +385,7 @@ Move generate_move_if_legal(const Position &pos, Move m, Bitboard pinned) { // 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); @@ -437,13 +396,13 @@ Move generate_move_if_legal(const Position &pos, Move m, Bitboard pinned) { // 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)); + assert(pos.piece_on(to - pawn_push(us)) == piece_of_color_and_type(them, PAWN)); - // 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); } // Castling moves @@ -453,11 +412,11 @@ Move generate_move_if_legal(const Position &pos, Move m, Bitboard pinned) { // 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)); - assert(pos.piece_on(to) == rook_of_color(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); @@ -477,7 +436,7 @@ Move generate_move_if_legal(const Position &pos, Move m, Bitboard pinned) { 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)) @@ -486,11 +445,11 @@ Move generate_move_if_legal(const Position &pos, Move m, Bitboard pinned) { // 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)); - assert(pos.piece_on(to) == rook_of_color(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); @@ -507,28 +466,28 @@ Move generate_move_if_legal(const Position &pos, Move m, Bitboard pinned) { illegal = true; if ( square_file(to) == FILE_B - && ( pos.piece_on(to + DELTA_W) == rook_of_color(them) - || pos.piece_on(to + DELTA_W) == queen_of_color(them))) + && ( 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 ? 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 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_promotion(m)) - return MOVE_NONE; + return false; // Proceed according to the square delta between the source and // destionation squares. @@ -541,14 +500,14 @@ Move generate_move_if_legal(const Position &pos, Move m, Bitboard pinned) { // 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: @@ -558,7 +517,7 @@ Move generate_move_if_legal(const Position &pos, Move m, Bitboard pinned) { 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: @@ -568,359 +527,386 @@ Move generate_move_if_legal(const Position &pos, Move m, Bitboard pinned) { 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); } // 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); + return ( pos.piece_attacks_square(pos.piece_on(from), from, to) + && pos.pl_move_is_legal(m) + && !move_promotion(m)); } namespace { template - int generate_piece_moves(const Position &pos, MoveStack *mlist, - Color side, Bitboard target) { - int n = 0; - for (int i = 0; i < pos.piece_count(side, Piece); i++) + 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++) { - Square from = pos.piece_list(side, Piece, i); - Bitboard b = pos.piece_attacks(from) & target; - while (b) - { - Square to = pop_1st_bit(&b); - mlist[n++].move = make_move(from, to); - } + from = pos.piece_list(us, Piece, i); + b = pos.piece_attacks(from) & target; + SERIALIZE_MOVES(b); } - return n; + return mlist; } - template - int generate_piece_blocking_evasions(const Position& pos, Bitboard b, - Bitboard blockSquares, MoveStack* mlist, int n) { - while (b) + MoveStack* generate_piece_moves(const Position& pos, MoveStack* mlist, + Color us, Bitboard target, Bitboard pinned) { + Square from; + Bitboard b; + + for (int i = 0, e = pos.piece_count(us, Piece); i < e; i++) { - Square from = pop_1st_bit(&b); - Bitboard bb = pos.piece_attacks(from) & blockSquares; - while (bb) - { - Square to = pop_1st_bit(&bb); - mlist[n++].move = make_move(from, to); - } + from = pos.piece_list(us, Piece, i); + if (pinned && bit_is_set(pinned, from)) + continue; + + b = pos.piece_attacks(from) & target; + SERIALIZE_MOVES(b); } - return n; + return mlist; } + template<> + MoveStack* generate_piece_moves(const Position& pos, MoveStack* mlist, Color us, Bitboard target) { - template - int generate_pawn_captures(const Position& pos, MoveStack* mlist) { + Bitboard b; + Square from = pos.king_square(us); - static const PawnParams PP = (C == WHITE ? WhitePawnParams : BlackPawnParams); + b = pos.piece_attacks(from) & target; + SERIALIZE_MOVES(b); + return mlist; + } - Bitboard pawns = pos.pawns(PP.us); - Bitboard enemyPieces = pos.pieces_of_color(PP.them); - Square sq; - int n = 0; + template + MoveStack* generate_pawn_captures(const Position& pos, MoveStack* mlist) { + + Square to; + Bitboard pawns = pos.pawns(Us); + Bitboard enemyPieces = pos.pieces_of_color(Them); // Captures in the a1-h8 (a8-h1 for black) direction - Bitboard b1 = (C == WHITE ? pawns << 9 : pawns >> 7) & ~FileABB & enemyPieces; + Bitboard b1 = (Us == WHITE ? pawns << 9 : pawns >> 7) & ~FileABB & enemyPieces; // Capturing promotions - Bitboard b2 = b1 & PP.Rank8BB; + Bitboard b2 = b1 & TRank8BB; while (b2) { - sq = pop_1st_bit(&b2); - mlist[n++].move = make_promotion_move(sq - PP.DELTA_NE, sq, QUEEN); + to = pop_1st_bit(&b2); + (*mlist++).move = make_promotion_move(to - TDELTA_NE, to, QUEEN); } // Capturing non-promotions - b2 = b1 & ~PP.Rank8BB; + b2 = b1 & ~TRank8BB; while (b2) { - sq = pop_1st_bit(&b2); - mlist[n++].move = make_move(sq - PP.DELTA_NE, sq); + to = pop_1st_bit(&b2); + (*mlist++).move = make_move(to - TDELTA_NE, to); } // Captures in the h1-a8 (h8-a1 for black) direction - b1 = (C == WHITE ? pawns << 7 : pawns >> 9) & ~FileHBB & enemyPieces; + b1 = (Us == WHITE ? pawns << 7 : pawns >> 9) & ~FileHBB & enemyPieces; // Capturing promotions - b2 = b1 & PP.Rank8BB; + b2 = b1 & TRank8BB; while (b2) { - sq = pop_1st_bit(&b2); - mlist[n++].move = make_promotion_move(sq - PP.DELTA_NW, sq, QUEEN); + to = pop_1st_bit(&b2); + (*mlist++).move = make_promotion_move(to - TDELTA_NW, to, QUEEN); } // Capturing non-promotions - b2 = b1 & ~PP.Rank8BB; + b2 = b1 & ~TRank8BB; while (b2) { - sq = pop_1st_bit(&b2); - mlist[n++].move = make_move(sq - PP.DELTA_NW, sq); + to = pop_1st_bit(&b2); + (*mlist++).move = make_move(to - TDELTA_NW, to); } // Non-capturing promotions - b1 = (C == WHITE ? pawns << 8 : pawns >> 8) & pos.empty_squares() & Rank8BB; + b1 = (Us == WHITE ? pawns << 8 : pawns >> 8) & pos.empty_squares() & TRank8BB; while (b1) { - sq = pop_1st_bit(&b1); - mlist[n++].move = make_promotion_move(sq - PP.DELTA_N, sq, QUEEN); + to = pop_1st_bit(&b1); + (*mlist++).move = make_promotion_move(to - TDELTA_N, to, QUEEN); } // En passant captures if (pos.ep_square() != SQ_NONE) { - assert(PP.us != WHITE || square_rank(pos.ep_square()) == RANK_6); - assert(PP.us != BLACK || square_rank(pos.ep_square()) == RANK_3); + assert(Us != WHITE || square_rank(pos.ep_square()) == RANK_6); + assert(Us != BLACK || square_rank(pos.ep_square()) == RANK_3); - b1 = pawns & pos.pawn_attacks(PP.them, pos.ep_square()); + b1 = pawns & pos.pawn_attacks(Them, pos.ep_square()); assert(b1 != EmptyBoardBB); while (b1) { - sq = pop_1st_bit(&b1); - mlist[n++].move = make_ep_move(sq, pos.ep_square()); + to = pop_1st_bit(&b1); + (*mlist++).move = make_ep_move(to, pos.ep_square()); } } - return n; + return mlist; } + template + MoveStack* generate_pawn_noncaptures(const Position& pos, MoveStack* mlist) { - template - int generate_pawn_noncaptures(const Position& pos, MoveStack* mlist) { - - static const PawnParams PP = (C == WHITE ? WhitePawnParams : BlackPawnParams); - - Bitboard pawns = pos.pawns(PP.us); - Bitboard enemyPieces = pos.pieces_of_color(PP.them); + Bitboard pawns = pos.pawns(Us); + Bitboard enemyPieces = pos.pieces_of_color(Them); Bitboard emptySquares = pos.empty_squares(); Bitboard b1, b2; - Square sq; - int n = 0; + Square to; // Underpromotion captures in the a1-h8 (a8-h1 for black) direction - b1 = (C == WHITE ? pawns << 9 : pawns >> 7) & ~FileABB & enemyPieces & PP.Rank8BB; + b1 = (Us == WHITE ? pawns << 9 : pawns >> 7) & ~FileABB & enemyPieces & TRank8BB; while (b1) { - sq = pop_1st_bit(&b1); - mlist[n++].move = make_promotion_move(sq - PP.DELTA_NE, sq, ROOK); - mlist[n++].move = make_promotion_move(sq - PP.DELTA_NE, sq, BISHOP); - mlist[n++].move = make_promotion_move(sq - PP.DELTA_NE, sq, KNIGHT); + 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); } // Underpromotion captures in the h1-a8 (h8-a1 for black) direction - b1 = (C == WHITE ? pawns << 7 : pawns >> 9) & ~FileHBB & enemyPieces & PP.Rank8BB; + b1 = (Us == WHITE ? pawns << 7 : pawns >> 9) & ~FileHBB & enemyPieces & TRank8BB; while (b1) { - sq = pop_1st_bit(&b1); - mlist[n++].move = make_promotion_move(sq - PP.DELTA_NW, sq, ROOK); - mlist[n++].move = make_promotion_move(sq - PP.DELTA_NW, sq, BISHOP); - mlist[n++].move = make_promotion_move(sq - PP.DELTA_NW, sq, KNIGHT); + 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); } // Single pawn pushes - b1 = (C == WHITE ? pawns << 8 : pawns >> 8) & emptySquares; - b2 = b1 & PP.Rank8BB; + b1 = (Us == WHITE ? pawns << 8 : pawns >> 8) & emptySquares; + b2 = b1 & TRank8BB; while (b2) { - sq = pop_1st_bit(&b2); - mlist[n++].move = make_promotion_move(sq - PP.DELTA_N, sq, ROOK); - mlist[n++].move = make_promotion_move(sq - PP.DELTA_N, sq, BISHOP); - mlist[n++].move = make_promotion_move(sq - PP.DELTA_N, sq, 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 & ~PP.Rank8BB; + b2 = b1 & ~TRank8BB; while (b2) { - sq = pop_1st_bit(&b2); - mlist[n++].move = make_move(sq - PP.DELTA_N, sq); + to = pop_1st_bit(&b2); + (*mlist++).move = make_move(to - TDELTA_N, to); } // Double pawn pushes - b2 = (C == WHITE ? (b1 & PP.Rank3BB) << 8 : (b1 & PP.Rank3BB) >> 8) & emptySquares; + b2 = (Us == WHITE ? (b1 & TRank3BB) << 8 : (b1 & TRank3BB) >> 8) & emptySquares; while (b2) { - sq = pop_1st_bit(&b2); - mlist[n++].move = make_move(sq - PP.DELTA_N - PP.DELTA_N, sq); + to = pop_1st_bit(&b2); + (*mlist++).move = make_move(to - TDELTA_N - TDELTA_N, to); } - return n; + return mlist; } - template - int generate_pawn_checks(const Position& pos, Bitboard dc, Square ksq, MoveStack* mlist, int n) + template + MoveStack* generate_pawn_checks(const Position& pos, Bitboard dc, Square ksq, MoveStack* mlist) { - static const PawnParams PP = (C == WHITE ? WhitePawnParams : BlackPawnParams); - - // Pawn moves which give 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. - Bitboard empty = pos.empty_squares(); - // Find all friendly pawns not on the enemy king's file - Bitboard b1 = pos.pawns(pos.side_to_move()) & ~file_bb(ksq), b2, b3; + Bitboard b1, b2, b3; + Bitboard empty = pos.empty_squares(); - // Discovered checks, single pawn pushes - b2 = b3 = (C == WHITE ? (b1 & dc) << 8 : (b1 & dc) >> 8) & ~PP.Rank8BB & empty; - while (b3) + if (dc != EmptyBoardBB) { - Square to = pop_1st_bit(&b3); - mlist[n++].move = make_move(to - PP.DELTA_N, to); - } + // 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 = pos.pawns(Us) & ~file_bb(ksq); + + // 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); + (*mlist++).move = make_move(to - TDELTA_N, to); + } - // Discovered checks, double pawn pushes - b3 = (C == WHITE ? (b2 & PP.Rank3BB) << 8 : (b2 & PP.Rank3BB) >> 8) & empty; - while (b3) - { - Square to = pop_1st_bit(&b3); - mlist[n++].move = make_move(to - PP.DELTA_N - PP.DELTA_N, to); + // Discovered checks, double pawn pushes + b3 = (Us == WHITE ? (b2 & TRank3BB) << 8 : (b2 & TRank3BB) >> 8) & empty; + while (b3) + { + Square to = pop_1st_bit(&b3); + (*mlist++).move = make_move(to - TDELTA_N - TDELTA_N, to); + } } // Direct checks. These are possible only for pawns on neighboring files - // of the enemy king - - b1 &= (~dc & neighboring_files_bb(ksq)); // FIXME why ~dc ?? + // of the enemy king. + b1 = pos.pawns(Us) & neighboring_files_bb(ksq) & ~dc; // Direct checks, single pawn pushes - b2 = (C == WHITE ? b1 << 8 : b1 >> 8) & empty; - b3 = b2 & pos.pawn_attacks(PP.them, ksq); + b2 = (Us == WHITE ? b1 << 8 : b1 >> 8) & empty; + b3 = b2 & pos.pawn_attacks(Them, ksq); while (b3) { Square to = pop_1st_bit(&b3); - mlist[n++].move = make_move(to - PP.DELTA_N, to); + (*mlist++).move = make_move(to - TDELTA_N, to); } // Direct checks, double pawn pushes - b3 = (C == WHITE ? (b2 & PP.Rank3BB) << 8 : (b2 & PP.Rank3BB) >> 8) + b3 = (Us == WHITE ? (b2 & TRank3BB) << 8 : (b2 & TRank3BB) >> 8) & empty - & pos.pawn_attacks(PP.them, ksq); - + & pos.pawn_attacks(Them, ksq); while (b3) { Square to = pop_1st_bit(&b3); - mlist[n++].move = make_move(to - PP.DELTA_N - PP.DELTA_N, to); + (*mlist++).move = make_move(to - TDELTA_N - TDELTA_N, to); } - return n; + return mlist; } + template + MoveStack* generate_piece_checks(const Position& pos, MoveStack* mlist, Color us, + Bitboard dc, Square ksq) { + + Bitboard target = pos.pieces_of_color_and_type(us, Piece); + + // Discovered checks + Bitboard b = target & dc; + while (b) + { + Square from = pop_1st_bit(&b); + Bitboard bb = pos.piece_attacks(from) & pos.empty_squares(); + if (Piece == KING) + bb &= ~QueenPseudoAttacks[ksq]; + + SERIALIZE_MOVES(bb); + } + + // Direct checks + b = target & ~dc; + if (Piece == KING || !b) + return mlist; - template - int generate_pawn_blocking_evasions(const Position& pos, Bitboard not_pinned, - Bitboard blockSquares, MoveStack* mlist, int n) { + Bitboard checkSqs = pos.piece_attacks(ksq) & pos.empty_squares(); + while (b) + { + Square from = pop_1st_bit(&b); + Bitboard bb = pos.piece_attacks(from) & checkSqs; + SERIALIZE_MOVES(bb); + } + return mlist; + } - static const PawnParams PP = (C == WHITE ? WhitePawnParams : BlackPawnParams); + template + MoveStack* generate_pawn_blocking_evasions(const Position& pos, Bitboard pinned, + Bitboard blockSquares, MoveStack* mlist) { + Square to; // Find non-pinned pawns - Bitboard b1 = pos.pawns(PP.us) & not_pinned; + Bitboard b1 = pos.pawns(Us) & ~pinned; // Single pawn pushes. We don't have to AND with empty squares here, // because the blocking squares will always be empty. - Bitboard b2 = (C == WHITE ? b1 << 8 : b1 >> 8) & blockSquares; + Bitboard b2 = (Us == WHITE ? b1 << 8 : b1 >> 8) & blockSquares; while (b2) { - Square to = pop_1st_bit(&b2); + to = pop_1st_bit(&b2); assert(pos.piece_on(to) == EMPTY); - if (square_rank(to) == PP.RANK_8) + if (square_rank(to) == TRANK_8) { - mlist[n++].move = make_promotion_move(to - PP.DELTA_N, to, QUEEN); - mlist[n++].move = make_promotion_move(to - PP.DELTA_N, to, ROOK); - mlist[n++].move = make_promotion_move(to - PP.DELTA_N, to, BISHOP); - mlist[n++].move = make_promotion_move(to - PP.DELTA_N, to, KNIGHT); + (*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[n++].move = make_move(to - PP.DELTA_N, to); + (*mlist++).move = make_move(to - TDELTA_N, to); } // Double pawn pushes - b2 = (C == WHITE ? b1 << 8 : b1 >> 8) & pos.empty_squares() & PP.Rank3BB; - b2 = (C == WHITE ? b2 << 8 : b2 >> 8) & blockSquares;; + b2 = (Us == WHITE ? b1 << 8 : b1 >> 8) & pos.empty_squares() & TRank3BB; + b2 = (Us == WHITE ? b2 << 8 : b2 >> 8) & blockSquares; while (b2) { - Square to = pop_1st_bit(&b2); + to = pop_1st_bit(&b2); assert(pos.piece_on(to) == EMPTY); - assert(PP.us != WHITE || square_rank(to) == RANK_4); - assert(PP.us != BLACK || square_rank(to) == RANK_5); + assert(Us != WHITE || square_rank(to) == RANK_4); + assert(Us != BLACK || square_rank(to) == RANK_5); - mlist[n++].move = make_move(to - PP.DELTA_N - PP.DELTA_N, to); + (*mlist++).move = make_move(to - TDELTA_N - TDELTA_N, to); } - return n; + return mlist; } + template + MoveStack* generate_castle_moves(const Position& pos, MoveStack* mlist) { - int generate_castle_moves(const Position &pos, MoveStack *mlist, Color us) { + Color us = pos.side_to_move(); - int n = 0; - - 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)); + Square ksq = pos.king_square(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(ksq) == piece_of_color_and_type(us, KING)); - 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) == piece_of_color_and_type(us, ROOK)); - for (s = Min(rsq, f1); s <= Max(rsq, f1); s++) - if (s != ksq && s != rsq && pos.square_is_occupied(s)) - illegal = true; + // 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; - if (!illegal) - mlist[n++].move = make_castle_move(ksq, rsq); - } + for (s = Min(rsq, s2); s <= Max(rsq, s2); s++) + if (s != ksq && s != rsq && pos.square_is_occupied(s)) + illegal = true; - 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; - - assert(pos.piece_on(rsq) == rook_of_color(us)); - - 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 - && ( pos.piece_on(relative_square(us, SQ_A1)) == rook_of_color(them) - || pos.piece_on(relative_square(us, SQ_A1)) == queen_of_color(them))) + if ( Side == QUEEN_SIDE + && square_file(rsq) == FILE_B + && ( pos.piece_on(relative_square(us, SQ_A1)) == piece_of_color_and_type(them, ROOK) + || pos.piece_on(relative_square(us, SQ_A1)) == piece_of_color_and_type(them, QUEEN))) illegal = true; - + if (!illegal) - mlist[n++].move = make_castle_move(ksq, rsq); - } + (*mlist++).move = make_castle_move(ksq, rsq); } - return n; + 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))); } }