} else if (last_coor > c->pos) {
fprintf(stderr, "[bam_index_core] the alignment is not sorted (%s): %u > %u in %d-th chr\n",
bam1_qname(b), last_coor, c->pos, c->tid+1);
} else if (last_coor > c->pos) {
fprintf(stderr, "[bam_index_core] the alignment is not sorted (%s): %u > %u in %d-th chr\n",
bam1_qname(b), last_coor, c->pos, c->tid+1);