++r->anno[0<<2|is_diff<<1|bam1_strand(p->b)];
min_dist = p->b->core.l_qseq - 1 - p->qpos;
if (min_dist > p->qpos) min_dist = p->qpos;
++r->anno[0<<2|is_diff<<1|bam1_strand(p->b)];
min_dist = p->b->core.l_qseq - 1 - p->qpos;
if (min_dist > p->qpos) min_dist = p->qpos;