diff --git a/Makefile b/Makefile
index e11a04d..f14d906 100644
--- a/Makefile
+++ b/Makefile
@@ -3,10 +3,9 @@ CFLAGS=		-g -Wall -O2
 CXXFLAGS=	$(CFLAGS)
 AR=			ar
 DFLAGS=		-DHAVE_PTHREAD #-D_NO_SSE2 #-D_FILE_OFFSET_BITS=64
-LOBJS=		bamlite.o utils.o bwt.o bwtio.o bwtaln.o bwtgap.o bntseq.o bwamem.o bwamem_pair.o stdaln.o \
-			bwaseqio.o bwase.o kstring.o
-AOBJS=		QSufSort.o bwt_gen.o \
-			is.o bwtmisc.o bwtindex.o ksw.o bwape.o \
+LOBJS=		utils.o kstring.o ksw.o bwt.o bntseq.o bwamem.o bwamem_pair.o
+AOBJS=		QSufSort.o bwt_gen.o stdaln.o bwase.o bwaseqio.o bwtgap.o bwtaln.o bamlite.o \
+			is.o bwtmisc.o bwtindex.o bwape.o \
 			bwtsw2_core.o bwtsw2_main.o bwtsw2_aux.o bwt_lite.o \
 			bwtsw2_chain.o fastmap.o bwtsw2_pair.o
 PROG=		bwa
diff --git a/bwase.c b/bwase.c
index 8fa79ac..1f36aaa 100644
--- a/bwase.c
+++ b/bwase.c
@@ -489,17 +489,6 @@ void bwa_print_sam1(const bntseq_t *bns, bwa_seq_t *p, const bwa_seq_t *mate, in
 	}
 }
 
-bntseq_t *bwa_open_nt(const char *prefix)
-{
-	bntseq_t *ntbns;
-	char *str;
-	str = (char*)calloc(strlen(prefix) + 10, 1);
-	strcat(strcpy(str, prefix), ".nt");
-	ntbns = bns_restore(str);
-	free(str);
-	return ntbns;
-}
-
 void bwa_print_sam_SQ(const bntseq_t *bns)
 {
 	int i;
diff --git a/bwt.c b/bwt.c
index 2903daa..7b37fe5 100644
--- a/bwt.c
+++ b/bwt.c
@@ -338,3 +338,79 @@ int bwt_smem1(const bwt_t *bwt, int len, const uint8_t *q, int x, int min_intv,
 	if (tmpvec == 0 || tmpvec[1] == 0) free(a[1].a);
 	return ret;
 }
+
+/*************************
+ * Read/write BWT and SA *
+ *************************/
+
+void bwt_dump_bwt(const char *fn, const bwt_t *bwt)
+{
+	FILE *fp;
+	fp = xopen(fn, "wb");
+	fwrite(&bwt->primary, sizeof(bwtint_t), 1, fp);
+	fwrite(bwt->L2+1, sizeof(bwtint_t), 4, fp);
+	fwrite(bwt->bwt, 4, bwt->bwt_size, fp);
+	fclose(fp);
+}
+
+void bwt_dump_sa(const char *fn, const bwt_t *bwt)
+{
+	FILE *fp;
+	fp = xopen(fn, "wb");
+	fwrite(&bwt->primary, sizeof(bwtint_t), 1, fp);
+	fwrite(bwt->L2+1, sizeof(bwtint_t), 4, fp);
+	fwrite(&bwt->sa_intv, sizeof(bwtint_t), 1, fp);
+	fwrite(&bwt->seq_len, sizeof(bwtint_t), 1, fp);
+	fwrite(bwt->sa + 1, sizeof(bwtint_t), bwt->n_sa - 1, fp);
+	fclose(fp);
+}
+
+void bwt_restore_sa(const char *fn, bwt_t *bwt)
+{
+	char skipped[256];
+	FILE *fp;
+	bwtint_t primary;
+
+	fp = xopen(fn, "rb");
+	fread(&primary, sizeof(bwtint_t), 1, fp);
+	xassert(primary == bwt->primary, "SA-BWT inconsistency: primary is not the same.");
+	fread(skipped, sizeof(bwtint_t), 4, fp); // skip
+	fread(&bwt->sa_intv, sizeof(bwtint_t), 1, fp);
+	fread(&primary, sizeof(bwtint_t), 1, fp);
+	xassert(primary == bwt->seq_len, "SA-BWT inconsistency: seq_len is not the same.");
+
+	bwt->n_sa = (bwt->seq_len + bwt->sa_intv) / bwt->sa_intv;
+	bwt->sa = (bwtint_t*)calloc(bwt->n_sa, sizeof(bwtint_t));
+	bwt->sa[0] = -1;
+
+	fread(bwt->sa + 1, sizeof(bwtint_t), bwt->n_sa - 1, fp);
+	fclose(fp);
+}
+
+bwt_t *bwt_restore_bwt(const char *fn)
+{
+	bwt_t *bwt;
+	FILE *fp;
+
+	bwt = (bwt_t*)calloc(1, sizeof(bwt_t));
+	fp = xopen(fn, "rb");
+	fseek(fp, 0, SEEK_END);
+	bwt->bwt_size = (ftell(fp) - sizeof(bwtint_t) * 5) >> 2;
+	bwt->bwt = (uint32_t*)calloc(bwt->bwt_size, 4);
+	fseek(fp, 0, SEEK_SET);
+	fread(&bwt->primary, sizeof(bwtint_t), 1, fp);
+	fread(bwt->L2+1, sizeof(bwtint_t), 4, fp);
+	fread(bwt->bwt, 4, bwt->bwt_size, fp);
+	bwt->seq_len = bwt->L2[4];
+	fclose(fp);
+	bwt_gen_cnt_table(bwt);
+
+	return bwt;
+}
+
+void bwt_destroy(bwt_t *bwt)
+{
+	if (bwt == 0) return;
+	free(bwt->sa); free(bwt->bwt);
+	free(bwt);
+}
diff --git a/bwtio.c b/bwtio.c
deleted file mode 100644
index 7508609..0000000
--- a/bwtio.c
+++ /dev/null
@@ -1,77 +0,0 @@
-#include <string.h>
-#include <stdio.h>
-#include <stdlib.h>
-#include "bwt.h"
-#include "utils.h"
-
-void bwt_dump_bwt(const char *fn, const bwt_t *bwt)
-{
-	FILE *fp;
-	fp = xopen(fn, "wb");
-	fwrite(&bwt->primary, sizeof(bwtint_t), 1, fp);
-	fwrite(bwt->L2+1, sizeof(bwtint_t), 4, fp);
-	fwrite(bwt->bwt, 4, bwt->bwt_size, fp);
-	fclose(fp);
-}
-
-void bwt_dump_sa(const char *fn, const bwt_t *bwt)
-{
-	FILE *fp;
-	fp = xopen(fn, "wb");
-	fwrite(&bwt->primary, sizeof(bwtint_t), 1, fp);
-	fwrite(bwt->L2+1, sizeof(bwtint_t), 4, fp);
-	fwrite(&bwt->sa_intv, sizeof(bwtint_t), 1, fp);
-	fwrite(&bwt->seq_len, sizeof(bwtint_t), 1, fp);
-	fwrite(bwt->sa + 1, sizeof(bwtint_t), bwt->n_sa - 1, fp);
-	fclose(fp);
-}
-
-void bwt_restore_sa(const char *fn, bwt_t *bwt)
-{
-	char skipped[256];
-	FILE *fp;
-	bwtint_t primary;
-
-	fp = xopen(fn, "rb");
-	fread(&primary, sizeof(bwtint_t), 1, fp);
-	xassert(primary == bwt->primary, "SA-BWT inconsistency: primary is not the same.");
-	fread(skipped, sizeof(bwtint_t), 4, fp); // skip
-	fread(&bwt->sa_intv, sizeof(bwtint_t), 1, fp);
-	fread(&primary, sizeof(bwtint_t), 1, fp);
-	xassert(primary == bwt->seq_len, "SA-BWT inconsistency: seq_len is not the same.");
-
-	bwt->n_sa = (bwt->seq_len + bwt->sa_intv) / bwt->sa_intv;
-	bwt->sa = (bwtint_t*)calloc(bwt->n_sa, sizeof(bwtint_t));
-	bwt->sa[0] = -1;
-
-	fread(bwt->sa + 1, sizeof(bwtint_t), bwt->n_sa - 1, fp);
-	fclose(fp);
-}
-
-bwt_t *bwt_restore_bwt(const char *fn)
-{
-	bwt_t *bwt;
-	FILE *fp;
-
-	bwt = (bwt_t*)calloc(1, sizeof(bwt_t));
-	fp = xopen(fn, "rb");
-	fseek(fp, 0, SEEK_END);
-	bwt->bwt_size = (ftell(fp) - sizeof(bwtint_t) * 5) >> 2;
-	bwt->bwt = (uint32_t*)calloc(bwt->bwt_size, 4);
-	fseek(fp, 0, SEEK_SET);
-	fread(&bwt->primary, sizeof(bwtint_t), 1, fp);
-	fread(bwt->L2+1, sizeof(bwtint_t), 4, fp);
-	fread(bwt->bwt, 4, bwt->bwt_size, fp);
-	bwt->seq_len = bwt->L2[4];
-	fclose(fp);
-	bwt_gen_cnt_table(bwt);
-
-	return bwt;
-}
-
-void bwt_destroy(bwt_t *bwt)
-{
-	if (bwt == 0) return;
-	free(bwt->sa); free(bwt->bwt);
-	free(bwt);
-}
diff --git a/fastmap.c b/fastmap.c
index 91a4ecb..d52a315 100644
--- a/fastmap.c
+++ b/fastmap.c
@@ -17,7 +17,7 @@ int main_mem(int argc, char *argv[])
 	mem_opt_t *opt;
 	bwt_t *bwt;
 	bntseq_t *bns;
-	int c, n;
+	int c, n, l;
 	gzFile fp, fp2 = 0;
 	kseq_t *ks, *ks2 = 0;
 	uint8_t *pac = 0;
@@ -57,6 +57,8 @@ int main_mem(int argc, char *argv[])
 		pac = calloc(bns->l_pac/4+1, 1);
 		fread(pac, 1, bns->l_pac/4+1, bns->fp_pac);
 	}
+	for (l = 0; l < bns->n_seqs; ++l)
+		printf("@SQ\tSN:%s\tLN:%d\n", bns->anns[l].name, bns->anns[l].len);
 
 	fp = strcmp(argv[optind + 1], "-")? gzopen(argv[optind + 1], "r") : gzdopen(fileno(stdin), "r");
 	ks = kseq_init(fp);
diff --git a/utils.c b/utils.c
index 127c8fe..1cebaab 100644
--- a/utils.c
+++ b/utils.c
@@ -40,6 +40,10 @@
 KSORT_INIT(128, pair64_t, pair64_lt)
 KSORT_INIT(64,  uint64_t, ks_lt_generic)
 
+/********************
+ * System utilities *
+ ********************/
+
 FILE *err_xopen_core(const char *func, const char *fn, const char *mode)
 {
 	FILE *fp = 0;