@param htsfp Htsfile pointer for the input file @param itr Iterator @param r Pointer to a bam1_t struct @return >= 0 on success; -1 when there is no more data; < -1 on error
See Implementation
@param htsfp Htsfile pointer for the input file @param itr Iterator @param r Pointer to a bam1_t struct @return >= 0 on success; -1 when there is no more data; < -1 on error