- if(piece == king_of_color(us)) {
- // 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) == rook_of_color(us))
- 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;
- for(s = from + delta;
- relative_rank(us, s) == RANK_1 && pos.piece_on(s) != rook_of_color(us);
- s += delta);
- if(relative_rank(us, s) == RANK_1 && pos.piece_on(s) == rook_of_color(us))
- return make_castle_move(from, s);
- }
- }
- else if(piece == pawn_of_color(us)) {
- // 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())
+ // En passant move? We assume that a pawn move is an en passant move
+ // if the destination square is epSquare.
+ if (to == pos.ep_square() && piece == piece_of_color_and_type(us, PAWN))