def split_virtual_offset(virtual_offset):
 start = (virtual_offset >> 16)
 return (start, (virtual_offset ^ (start << 16)))

def split_virtual_offset ( virtual_offset ) : start = ( virtual_offset >> 16 ) return ( start , ( virtual_offset ^ ( start << 16 ) ) )
divides a 64-bit bgzf virtual offset into block start & within block offsets .