-/// Position::undo_castle_move() is a private method used to unmake a castling
-/// move. It is called from the main Position::undo_move function. Note that
-/// castling moves are encoded as "king captures friendly rook" moves, for
-/// instance white short castling in a non-Chess960 game is encoded as e1h1.
-
-void Position::undo_castle_move(Move m) {
-
- assert(move_is_ok(m));
- assert(move_is_castle(m));
-
- // When we have arrived here, some work has already been done by
- // Position::undo_move. In particular, the side to move has been switched,
- // so the code below is correct.
- Color us = side_to_move();
-
- // Find source squares for king and rook
- Square kfrom = move_from(m);
- Square rfrom = move_to(m);
- Square kto, rto;
-
- // Find destination squares for king and rook
- if (rfrom > kfrom) // O-O
- {
- kto = relative_square(us, SQ_G1);
- rto = relative_square(us, SQ_F1);
- }
- else // O-O-O
- {
- kto = relative_square(us, SQ_C1);
- rto = relative_square(us, SQ_D1);
- }
-
- assert(piece_on(kto) == make_piece(us, KING));
- assert(piece_on(rto) == make_piece(us, ROOK));
-
- // Remove pieces from destination squares
- clear_bit(&byColorBB[us], kto);
- clear_bit(&byTypeBB[KING], kto);
- clear_bit(&byTypeBB[0], kto);
- clear_bit(&byColorBB[us], rto);
- clear_bit(&byTypeBB[ROOK], rto);
- clear_bit(&byTypeBB[0], rto);
-
- // Put pieces on source squares
- set_bit(&byColorBB[us], kfrom);
- set_bit(&byTypeBB[KING], kfrom);
- set_bit(&byTypeBB[0], kfrom);
- set_bit(&byColorBB[us], rfrom);
- set_bit(&byTypeBB[ROOK], rfrom);
- set_bit(&byTypeBB[0], rfrom);
-
- // Update board
- Piece king = make_piece(us, KING);
- Piece rook = make_piece(us, ROOK);
- board[kto] = board[rto] = PIECE_NONE;
- board[kfrom] = king;
- board[rfrom] = rook;
-
- // Update piece lists
- pieceList[us][KING][index[kto]] = kfrom;
- pieceList[us][ROOK][index[rto]] = rfrom;
- int tmp = index[rto]; // In Chess960 could be rto == kfrom
- index[kfrom] = index[kto];
- index[rfrom] = tmp;
-
- // Finally point our state pointer back to the previous state
- st = st->previous;
-
- assert(is_ok());
-}
-
-
-/// Position::do_null_move makes() a "null move": It switches the side to move
-/// and updates the hash key without executing any move on the board.
-