- if (piece == piece_of_color_and_type(us, KING))
- {
- // 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 (pos.piece_on(to) == piece_of_color_and_type(us, ROOK))
- return make_castle_move(from, to);
-
- else 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 + delta;
- while (relative_rank(us, s) == RANK_1 && pos.piece_on(s) != piece_of_color_and_type(us, ROOK))
- s += delta;
-
- return (relative_rank(us, s) == RANK_1 ? make_castle_move(from, s) : MOVE_NONE);
- }
- }
- else if (piece == piece_of_color_and_type(us, PAWN))
- {
- // En passant move? We assume that a pawn move is an en passant move
- // without further testing if the destination square is epSquare.
- if (to == pos.ep_square())
- return make_ep_move(from, to);
- }
- return make_move(from, to);