- // Is this a castling move? A king move is assumed to be a castling move
- // if the destination square is occupied by a friendly rook, or if the
- // distance between the source and destination squares is more than 1.
- if (piece == piece_of_color_and_type(us, KING))
- {
- if (pos.piece_on(to) == piece_of_color_and_type(us, ROOK))
- return make_castle_move(from, to);
-
- if (square_distance(from, to) > 1)
- {
- // This is a castling move, but we have to translate it to the
- // internal "king captures rook" representation.
- SquareDelta delta = (to > from ? DELTA_E : DELTA_W);
- Square s = from;
-
- do s += delta;
- while ( pos.piece_on(s) != piece_of_color_and_type(us, ROOK)
- && relative_rank(us, s) == RANK_1);
-
- return relative_rank(us, s) == RANK_1 ? make_castle_move(from, s) : MOVE_NONE;
- }
- }