-void Position::do_castle_move(Move m) {
-
- assert(is_ok(m));
- assert(is_castle(m));
-
- Square kto, kfrom, rfrom, rto, kAfter, rAfter;
-
- Color us = side_to_move();
- Square kBefore = move_from(m);
- Square rBefore = move_to(m);
-
- // Find after-castle squares for king and rook
- if (rBefore > kBefore) // O-O
- {
- kAfter = relative_square(us, SQ_G1);
- rAfter = relative_square(us, SQ_F1);
- }
- else // O-O-O
- {
- kAfter = relative_square(us, SQ_C1);
- rAfter = relative_square(us, SQ_D1);
- }
-
- kfrom = Do ? kBefore : kAfter;
- rfrom = Do ? rBefore : rAfter;
-
- kto = Do ? kAfter : kBefore;
- rto = Do ? rAfter : rBefore;
-
- assert(piece_on(kfrom) == make_piece(us, KING));
- assert(piece_on(rfrom) == make_piece(us, ROOK));
-
- // Remove pieces from source squares
- clear_bit(&byColorBB[us], kfrom);
- clear_bit(&byTypeBB[KING], kfrom);
- clear_bit(&occupied, kfrom);
- clear_bit(&byColorBB[us], rfrom);
- clear_bit(&byTypeBB[ROOK], rfrom);
- clear_bit(&occupied, rfrom);
-
- // Put pieces on destination squares
- set_bit(&byColorBB[us], kto);
- set_bit(&byTypeBB[KING], kto);
- set_bit(&occupied, kto);
- set_bit(&byColorBB[us], rto);
- set_bit(&byTypeBB[ROOK], rto);
- set_bit(&occupied, rto);
-
- // Update board
- Piece king = make_piece(us, KING);
- Piece rook = make_piece(us, ROOK);
- board[kfrom] = board[rfrom] = PIECE_NONE;
- board[kto] = king;
- board[rto] = rook;
-
- // Update piece lists
- pieceList[us][KING][index[kfrom]] = kto;
- pieceList[us][ROOK][index[rfrom]] = rto;
- int tmp = index[rfrom]; // In Chess960 could be kto == rfrom
- index[kto] = index[kfrom];
- index[rto] = tmp;
-
- if (Do)
- {
- // Reset capture field
- st->capturedType = PIECE_TYPE_NONE;
-
- // Update incremental scores
- st->value += pst_delta(king, kfrom, kto);
- st->value += pst_delta(rook, rfrom, rto);
-
- // Update hash key
- st->key ^= zobrist[us][KING][kfrom] ^ zobrist[us][KING][kto];
- st->key ^= zobrist[us][ROOK][rfrom] ^ zobrist[us][ROOK][rto];
-
- // Clear en passant square
- if (st->epSquare != SQ_NONE)
- {
- st->key ^= zobEp[st->epSquare];
- st->epSquare = SQ_NONE;
- }
-
- // Update castling rights
- st->key ^= zobCastle[st->castleRights];
- st->castleRights &= castleRightsMask[kfrom];
- st->key ^= zobCastle[st->castleRights];
-
- // Reset rule 50 counter
- st->rule50 = 0;
-
- // Update checkers BB
- st->checkersBB = attackers_to(king_square(flip(us))) & pieces(us);
-
- // Finish
- sideToMove = flip(sideToMove);
- st->value += (sideToMove == WHITE ? TempoValue : -TempoValue);
- }
- else
- // Undo: point our state pointer back to the previous state
- st = st->previous;
-
- assert(pos_is_ok());
+void Position::do_castling(Color us, Square from, Square& to, Square& rfrom, Square& rto) {
+
+ bool kingSide = to > from;
+ rfrom = to; // Castling is encoded as "king captures friendly rook"
+ rto = relative_square(us, kingSide ? SQ_F1 : SQ_D1);
+ to = relative_square(us, kingSide ? SQ_G1 : SQ_C1);
+
+ // Remove both pieces first since squares could overlap in Chess960
+ remove_piece(make_piece(us, KING), Do ? from : to);
+ remove_piece(make_piece(us, ROOK), Do ? rfrom : rto);
+ board[Do ? from : to] = board[Do ? rfrom : rto] = NO_PIECE; // Since remove_piece doesn't do it for us
+ put_piece(make_piece(us, KING), Do ? to : from);
+ put_piece(make_piece(us, ROOK), Do ? rto : rfrom);