uint static_bitsequence_sdarray::rank1(uint i) {
  if(i>=len) return -1;
  if(ones)
    return selects3_rank(&sd,i);
  else
    return 0;
}
	size_t BitSequenceSDArray::rank1(size_t i) const
	{
		if(i>=length) return -1;
		if(ones)
			return selects3_rank(&sd,i);
		else
			return 0;
	}