returns the number of empty squares starting from a1 . for example if this has occupied squares c2 and h5 , then since a1-h1 , a2 , and b2 are empty , the result would be 10 . if a1 is occupied the result is 0 . concode_field_sep long data concode_field_sep Bitboard bitboardFromFile concode_elem_sep void updateUnion concode_elem_sep void updateUnion concode_elem_sep boolean intersects concode_elem_sep boolean intersects concode_elem_sep boolean intersects concode_elem_sep void setData concode_elem_sep void updateRemove concode_elem_sep void updateRemove concode_elem_sep void clear concode_elem_sep boolean isEmpty concode_elem_sep Bitboard bitboardFromRank concode_elem_sep Bitboard union concode_elem_sep Bitboard union concode_elem_sep Bitboard intersection concode_elem_sep Bitboard intersection concode_elem_sep int numOccupied concode_elem_sep String toString concode_elem_sep Bitboard copy concode_elem_sep Bitboard flip concode_elem_sep long getData
int function ( ) { return Long . numberOfTrailingZeros ( this . data ) ; }