diff --git a/bseq.h b/bseq.h
index 5dfe095..015dca3 100644
--- a/bseq.h
+++ b/bseq.h
@@ -26,15 +26,19 @@ int mm_bseq_eof(mm_bseq_file_t *fp);
 extern unsigned char seq_nt4_table[256];
 extern unsigned char seq_comp_table[256];
 
+static inline int mm_qname_len(const char *s)
+{
+	int l;
+	l = strlen(s);
+	return l >= 3 && s[l-1] >= '0' && s[l-1] <= '9' && s[l-2] == '/'? l - 2 : l;
+}
+
 static inline int mm_qname_same(const char *s1, const char *s2)
 {
 	int l1, l2;
-	l1 = strlen(s1);
-	l2 = strlen(s2);
-	if (l1 != l2 || l1 < 3) return 0;
-	if (!(s1[l1-1] >= '0' && s1[l1-1] <= '9' && s1[l1-2] == '/')) return 0;
-	if (!(s2[l2-1] >= '0' && s2[l2-1] <= '9' && s2[l2-2] == '/')) return 0;
-	return (strncmp(s1, s2, l1 - 2) == 0);
+	l1 = mm_qname_len(s1);
+	l2 = mm_qname_len(s2);
+	return (l1 == l2 && strncmp(s1, s2, l1) == 0);
 }
 
 static inline void mm_revcomp_bseq(mm_bseq1_t *s)
diff --git a/format.c b/format.c
index 989e4ff..201b1c4 100644
--- a/format.c
+++ b/format.c
@@ -240,21 +240,30 @@ static void sam_write_sq(kstring_t *s, char *seq, int l, int rev, int comp)
 	} else str_copy(s, seq, seq + l);
 }
 
-void mm_write_sam(kstring_t *s, const mm_idx_t *mi, const mm_bseq1_t *t, const mm_reg1_t *r, int n_regs, const mm_reg1_t *regs)
+void mm_write_sam2(kstring_t *s, const mm_idx_t *mi, const mm_bseq1_t *t, int seg_idx, int reg_idx, int n_seg, const int *n_regss, const mm_reg1_t *const* regss, void *km)
 {
-	int flag = 0;
+	int flag = n_seg > 1? 0x1 : 0x0, n_regs = n_regss[seg_idx];
+	const mm_reg1_t *regs = regss[seg_idx];
+	const mm_reg1_t *r = n_regs > 0 && reg_idx < n_regs && reg_idx >= 0? &regs[reg_idx] : NULL;
+
+	// write QNAME
 	s->l = 0;
+	mm_sprintf_lite(s, "%s", t->name);
+	if (n_seg > 1) s->l = mm_qname_len(t->name); // trim the suffix like /1 or /2
+
+	// write up to CIGAR
 	if (r == 0) {
-		mm_sprintf_lite(s, "%s\t4\t*\t0\t0\t*\t*\t0\t0\t", t->name);
-		sam_write_sq(s, t->seq, t->l_seq, 0, 0);
-		mm_sprintf_lite(s, "\t");
-		if (t->qual) sam_write_sq(s, t->qual, t->l_seq, 0, 0);
-		else mm_sprintf_lite(s, "*");
+		mm_sprintf_lite(s, "\t4\t*\t0\t0\t*\t");
 	} else {
 		if (r->rev) flag |= 0x10;
 		if (r->parent != r->id) flag |= 0x100;
 		else if (!r->sam_pri) flag |= 0x800;
-		mm_sprintf_lite(s, "%s\t%d\t%s\t%d\t%d\t", t->name, flag, mi->seq[r->rid].name, r->rs+1, r->mapq);
+		if (n_seg > 1) {
+			if (seg_idx == 0) flag |= 0x40;
+			else if (seg_idx == n_seg - 1) flag |= 0x80;
+			// TODO: set 0x2!!!
+		}
+		mm_sprintf_lite(s, "\t%d\t%s\t%d\t%d\t", flag, mi->seq[r->rid].name, r->rs+1, r->mapq);
 		if (r->p) { // actually this should always be true for SAM output
 			uint32_t k, clip_len = r->rev? t->l_seq - r->qe : r->qs;
 			int clip_char = (flag&0x800)? 'H' : 'S';
@@ -264,7 +273,20 @@ void mm_write_sam(kstring_t *s, const mm_idx_t *mi, const mm_bseq1_t *t, const m
 			clip_len = r->rev? r->qs : t->l_seq - r->qe;
 			if (clip_len) mm_sprintf_lite(s, "%d%c", clip_len, clip_char);
 		} else mm_sprintf_lite(s, "*");
+	}
+
+	// write mate positions
+	if (n_seg > 1) {
 		mm_sprintf_lite(s, "\t*\t0\t0\t");
+	} else mm_sprintf_lite(s, "\t*\t0\t0\t");
+
+	// write SEQ and QUAL
+	if (r == 0) {
+		sam_write_sq(s, t->seq, t->l_seq, 0, 0);
+		mm_sprintf_lite(s, "\t");
+		if (t->qual) sam_write_sq(s, t->qual, t->l_seq, 0, 0);
+		else mm_sprintf_lite(s, "*");
+	} else {
 		if ((flag & 0x900) == 0) {
 			sam_write_sq(s, t->seq, t->l_seq, r->rev, r->rev);
 			mm_sprintf_lite(s, "\t");
@@ -278,8 +300,13 @@ void mm_write_sam(kstring_t *s, const mm_idx_t *mi, const mm_bseq1_t *t, const m
 			if (t->qual) sam_write_sq(s, t->qual + r->qs, r->qe - r->qs, r->rev, 0);
 			else mm_sprintf_lite(s, "*");
 		}
+	}
+
+	// write tags
+	if (mm_rg_id[0]) mm_sprintf_lite(s, "\tRG:Z:%s", mm_rg_id);
+	if (n_seg > 2) mm_sprintf_lite(s, "\tFI:i:%d", seg_idx);
+	if (r) {
 		write_tags(s, r);
-		if (mm_rg_id[0]) mm_sprintf_lite(s, "\tRG:Z:%s", mm_rg_id);
 		if (r->parent == r->id && r->p && n_regs > 1 && regs && r >= regs && r - regs < n_regs) { // supplementary aln may exist
 			int i, n_sa = 0; // n_sa: number of SA fields
 			for (i = 0; i < n_regs; ++i)
@@ -306,5 +333,14 @@ void mm_write_sam(kstring_t *s, const mm_idx_t *mi, const mm_bseq1_t *t, const m
 			}
 		}
 	}
+
 	s->s[s->l] = 0; // we always have room for an extra byte (see str_enlarge)
 }
+
+void mm_write_sam(kstring_t *s, const mm_idx_t *mi, const mm_bseq1_t *t, const mm_reg1_t *r, int n_regs, const mm_reg1_t *regs)
+{
+	int i;
+	for (i = 0; i < n_regs; ++i)
+		if (r == &regs[i]) break;
+	mm_write_sam2(s, mi, t, 0, i, 1, &n_regs, &regs, NULL);
+}
diff --git a/main.c b/main.c
index a1949b3..aefa7f4 100644
--- a/main.c
+++ b/main.c
@@ -6,7 +6,7 @@
 #include "mmpriv.h"
 #include "getopt.h"
 
-#define MM_VERSION "2.2-r468-dirty"
+#define MM_VERSION "2.2-r469-dirty"
 
 #ifdef __linux__
 #include <sys/resource.h>
diff --git a/map.c b/map.c
index 8b5a9aa..0b85473 100644
--- a/map.c
+++ b/map.c
@@ -410,7 +410,7 @@ static void worker_for(void *_data, long i, int tid) // kt_for() callback
 
 static void *worker_pipeline(void *shared, int step, void *in)
 {
-	int i, j;
+	int i, j, k;
     pipeline_t *p = (pipeline_t*)shared;
     if (step == 0) { // step 0: read sequences
 		int with_qual = (!!(p->opt->flag & MM_F_OUT_SAM) && !(p->opt->flag & MM_F_NO_QUAL));
@@ -448,29 +448,34 @@ static void *worker_pipeline(void *shared, int step, void *in)
 		for (i = 0; i < p->n_threads; ++i) mm_tbuf_destroy(s->buf[i]);
 		free(s->buf);
 		if ((p->opt->flag & MM_F_OUT_CS) && !(mm_dbg_flag & MM_DBG_NO_KALLOC)) km = km_init();
-		for (i = 0; i < s->n_seq; ++i) {
-			mm_bseq1_t *t = &s->seq[i];
-			for (j = 0; j < s->n_reg[i]; ++j) {
-				mm_reg1_t *r = &s->reg[i][j];
-				assert(!r->sam_pri || r->id == r->parent);
-				if ((p->opt->flag & MM_F_NO_PRINT_2ND) && r->id != r->parent)
-					continue;
-				if (p->opt->flag & MM_F_OUT_SAM)
-					mm_write_sam(&p->str, mi, t, r, s->n_reg[i], s->reg[i]);
-				else
-					mm_write_paf(&p->str, mi, t, r, km, p->opt->flag);
-				puts(p->str.s);
+		for (k = 0; k < s->n_frag; ++k) {
+			int seg_st = s->seg_off[k], seg_en = s->seg_off[k] + s->n_seg[k];
+			for (i = seg_st; i < seg_en; ++i) {
+				mm_bseq1_t *t = &s->seq[i];
+				for (j = 0; j < s->n_reg[i]; ++j) {
+					mm_reg1_t *r = &s->reg[i][j];
+					assert(!r->sam_pri || r->id == r->parent);
+					if ((p->opt->flag & MM_F_NO_PRINT_2ND) && r->id != r->parent)
+						continue;
+					if (p->opt->flag & MM_F_OUT_SAM)
+						mm_write_sam2(&p->str, mi, t, i - seg_st, j, s->n_seg[k], &s->n_reg[seg_st], (const mm_reg1_t*const*)&s->reg[seg_st], km);
+					else
+						mm_write_paf(&p->str, mi, t, r, km, p->opt->flag);
+					puts(p->str.s);
+				}
+				if (s->n_reg[i] == 0 && (p->opt->flag & MM_F_OUT_SAM)) {
+					mm_write_sam2(&p->str, mi, t, i - seg_st, -1, s->n_seg[k], &s->n_reg[seg_st], (const mm_reg1_t*const*)&s->reg[seg_st], km);
+					puts(p->str.s);
+				}
 			}
-			if (s->n_reg[i] == 0 && (p->opt->flag & MM_F_OUT_SAM)) {
-				mm_write_sam(&p->str, 0, t, 0, 0, 0);
-				puts(p->str.s);
+			for (i = seg_st; i < seg_en; ++i) {
+				for (j = 0; j < s->n_reg[i]; ++j) free(s->reg[i][j].p);
+				free(s->reg[i]);
+				free(s->seq[i].seq); free(s->seq[i].name);
+				if (s->seq[i].qual) free(s->seq[i].qual);
 			}
-			for (j = 0; j < s->n_reg[i]; ++j) free(s->reg[i][j].p);
-			free(s->reg[i]);
-			free(s->seq[i].seq); free(s->seq[i].name);
-			if (s->seq[i].qual) free(s->seq[i].qual);
 		}
-		free(s->reg); free(s->n_reg); free(s->seq);
+		free(s->reg); free(s->n_reg); free(s->seq); // seg_off and n_seg were allocated with reg; no memory leak here
 		km_destroy(km);
 		if (mm_verbose >= 3)
 			fprintf(stderr, "[M::%s::%.3f*%.2f] mapped %d sequences\n", __func__, realtime() - mm_realtime0, cputime() / (realtime() - mm_realtime0), s->n_seq);
diff --git a/mmpriv.h b/mmpriv.h
index a48a480..cbaef08 100644
--- a/mmpriv.h
+++ b/mmpriv.h
@@ -57,6 +57,7 @@ void mm_sketch(void *km, const char *str, int len, int w, int k, uint32_t rid, i
 void mm_write_sam_hdr(const mm_idx_t *mi, const char *rg, const char *ver, int argc, char *argv[]);
 void mm_write_paf(kstring_t *s, const mm_idx_t *mi, const mm_bseq1_t *t, const mm_reg1_t *r, void *km, int opt_flag);
 void mm_write_sam(kstring_t *s, const mm_idx_t *mi, const mm_bseq1_t *t, const mm_reg1_t *r, int n_regs, const mm_reg1_t *regs);
+void mm_write_sam2(kstring_t *s, const mm_idx_t *mi, const mm_bseq1_t *t, int seg_idx, int reg_idx, int n_seg, const int *n_regs, const mm_reg1_t *const* regs, void *km);
 
 void mm_idxopt_init(mm_idxopt_t *opt);
 const uint64_t *mm_idx_get(const mm_idx_t *mi, uint64_t minier, int *n);