diff --git a/.vscode/settings.json b/.vscode/settings.json
index 77e1001..fcdb4fc 100644
--- a/.vscode/settings.json
+++ b/.vscode/settings.json
@@ -9,6 +9,9 @@
         "istream": "c",
         "limits": "c",
         "bit": "c",
-        "numeric": "c"
+        "numeric": "c",
+        "fmt_idx.h": "c",
+        "kseq.h": "c",
+        "ksw.h": "c"
     }
 }
\ No newline at end of file
diff --git a/Makefile b/Makefile
index 263ee60..32656fd 100644
--- a/Makefile
+++ b/Makefile
@@ -1,18 +1,18 @@
 CC=			gcc
 #CC=			clang --analyze
 # CFLAGS=		-g -Wall -Wno-unused-function -O2
-CFLAGS=		-g -Wall -Wno-unused-function -O2
+CFLAGS=		-Wall -Wno-unused-function -mavx2 -O2
 WRAP_MALLOC=-DUSE_MALLOC_WRAPPERS
 SHOW_PERF=  -DSHOW_PERF
 AR=			ar
-DFLAGS=		-DHAVE_PTHREAD $(WRAP_MALLOC) $(SHOW_PERF)
+DFLAGS=		-DHAVE_PTHREAD $(WRAP_MALLOC) $(SHOW_PERF) -DUSE_AVX2 #-DUSE_MT_READ #-DFILTER_FULL_MATCH 
 LOBJS=		utils.o kthread.o kstring.o ksw.o bwt.o bntseq.o bwa.o bwamem.o bwamem_pair.o bwamem_extra.o malloc_wrap.o \
 			QSufSort.o bwt_gen.o rope.o rle.o is.o bwtindex.o
 AOBJS=		bwashm.o bwase.o bwaseqio.o bwtgap.o bwtaln.o bamlite.o \
 			bwape.o kopen.o pemerge.o maxk.o \
 			bwtsw2_core.o bwtsw2_main.o bwtsw2_aux.o bwt_lite.o \
 			bwtsw2_chain.o fastmap.o bwtsw2_pair.o \
-			fmt_idx.o
+			fmt_idx.o ksw_extend2_avx2.o ksw_extend2_avx2_u8.o
 PROG=		bwa
 INCLUDES=	
 LIBS=		-lm -lz -lpthread -ldl
@@ -29,11 +29,11 @@ endif
 
 all:$(PROG)
 
-bwa:libbwa.a $(AOBJS) main.o
-		$(CC) $(CFLAGS) $(LDFLAGS) $(AOBJS) main.o -o $@ -L. -lbwa $(LIBS)
-
 #bwa:libbwa.a $(AOBJS) main.o
-#		$(CC) $(CFLAGS) $(LDFLAGS) $(AOBJS) ../sbwa/jemalloc/lib/libjemalloc.a main.o -o $@ -L. -lbwa $(LIBS)
+#		$(CC) $(CFLAGS) $(LDFLAGS) $(AOBJS) main.o -o $@ -L. -lbwa $(LIBS)
+
+bwa:libbwa.a $(AOBJS) main.o
+		$(CC) $(CFLAGS) $(LDFLAGS) $(AOBJS) ../sbwa/jemalloc/lib/libjemalloc.a main.o -o $@ -L. -lbwa $(LIBS)
 
 bwamem-lite:libbwa.a example.o
 		$(CC) $(CFLAGS) $(LDFLAGS) example.o -o $@ -L. -lbwa $(LIBS)
diff --git a/bntseq.c b/bntseq.c
index c844992..c3c246a 100644
--- a/bntseq.c
+++ b/bntseq.c
@@ -423,6 +423,30 @@ uint8_t *bns_get_seq(int64_t l_pac, const uint8_t *pac, int64_t beg, int64_t end
 	return seq;
 }
 
+void bns_get_seq_no_alloc(int64_t l_pac, const uint8_t *pac, int64_t beg, int64_t end, int64_t *len, size_t *m_seq, uint8_t **seqp)
+{
+	if (end < beg) end ^= beg, beg ^= end, end ^= beg; // if end is smaller, swap
+	if (end > l_pac<<1) end = l_pac<<1;
+	if (beg < 0) beg = 0;
+	if (beg >= l_pac || end <= l_pac) {
+		int64_t k, l = 0;
+		*len = end - beg;
+		if (*len > *m_seq) {
+			*m_seq = *len;
+			*seqp = realloc(*seqp, end - beg);
+		}
+		if (beg >= l_pac) { // reverse strand
+			int64_t beg_f = (l_pac<<1) - 1 - end;
+			int64_t end_f = (l_pac<<1) - 1 - beg;
+			for (k = end_f; k > beg_f; --k)
+				(*seqp)[l++] = 3 - _get_pac(pac, k);
+		} else { // forward strand
+			for (k = beg; k < end; ++k)
+				(*seqp)[l++] = _get_pac(pac, k);
+		}
+	} else *len = 0; // if bridging the forward-reverse boundary, return nothing
+}
+
 uint8_t *bns_fetch_seq(const bntseq_t *bns, const uint8_t *pac, int64_t *beg, int64_t mid, int64_t *end, int *rid)
 {
 	int64_t far_beg, far_end, len;
@@ -449,3 +473,28 @@ uint8_t *bns_fetch_seq(const bntseq_t *bns, const uint8_t *pac, int64_t *beg, in
 	assert(seq && *end - *beg == len); // assertion failure should never happen
 	return seq;
 }
+
+void bns_fetch_seq_no_alloc(const bntseq_t *bns, const uint8_t *pac, int64_t *beg, int64_t mid, int64_t *end, int *rid, size_t *m_seq, uint8_t **seqp)
+{
+	int64_t far_beg, far_end, len;
+	int is_rev;
+
+	if (*end < *beg) *end ^= *beg, *beg ^= *end, *end ^= *beg; // if end is smaller, swap
+	assert(*beg <= mid && mid < *end);
+	*rid = bns_pos2rid(bns, bns_depos(bns, mid, &is_rev));
+	far_beg = bns->anns[*rid].offset;
+	far_end = far_beg + bns->anns[*rid].len;
+	if (is_rev) { // flip to the reverse strand
+		int64_t tmp = far_beg;
+		far_beg = (bns->l_pac<<1) - far_end;
+		far_end = (bns->l_pac<<1) - tmp;
+	}
+	*beg = *beg > far_beg? *beg : far_beg;
+	*end = *end < far_end? *end : far_end;
+	bns_get_seq_no_alloc(bns->l_pac, pac, *beg, *end, &len, m_seq, seqp);
+	if (*seqp == 0 || *end - *beg != len) {
+		fprintf(stderr, "[E::%s] begin=%ld, mid=%ld, end=%ld, len=%ld, seq=%p, rid=%d, far_beg=%ld, far_end=%ld\n",
+				__func__, (long)*beg, (long)mid, (long)*end, (long)len, *seqp, *rid, (long)far_beg, (long)far_end);
+	}
+	assert(*seqp && *end - *beg == len); // assertion failure should never happen
+}
diff --git a/bntseq.h b/bntseq.h
index 354adb6..7891d61 100644
--- a/bntseq.h
+++ b/bntseq.h
@@ -79,7 +79,7 @@ extern "C" {
 	uint8_t *bns_get_seq(int64_t l_pac, const uint8_t *pac, int64_t beg, int64_t end, int64_t *len);
 	uint8_t *bns_fetch_seq(const bntseq_t *bns, const uint8_t *pac, int64_t *beg, int64_t mid, int64_t *end, int *rid);
 	int bns_intv2rid(const bntseq_t *bns, int64_t rb, int64_t re);
-
+	void bns_fetch_seq_no_alloc(const bntseq_t *bns, const uint8_t *pac, int64_t *beg, int64_t mid, int64_t *end, int *rid, size_t *m_seq, uint8_t **seqp);
 #ifdef __cplusplus
 }
 #endif
diff --git a/bwa.c b/bwa.c
index ba14350..3002670 100644
--- a/bwa.c
+++ b/bwa.c
@@ -29,6 +29,7 @@
 #include <zlib.h>
 #include <assert.h>
 #include <unistd.h>
+#include <pthread.h>
 #include "bntseq.h"
 #include "bwa.h"
 #include "ksw.h"
@@ -58,31 +59,160 @@ static inline void trim_readno(kstring_t *s)
 		s->l -= 2, s->s[s->l] = 0;
 }
 
-static inline char *dupkstring(const kstring_t *str, int dupempty)
+static inline void dupkstring(const kstring_t *str, int dupempty, char **dstp, int *sm)
 {
-	char *s = (str->l > 0 || dupempty)? malloc(str->l + 1) : NULL;
-	if (!s) return NULL;
+	if (!dupempty && str->l == 0) {
+		if (*dstp) free(*dstp);
+		*dstp = 0; *sm = 0;
+	} else if (*dstp == 0 || *sm < str->l) {
+		*sm = str->l;
+		*dstp = realloc(*dstp, str->l + 1);
+	}
+
+	char *s = *dstp;
+	if (!s) return;
 
 	memcpy(s, str->s, str->l);
 	s[str->l] = '\0';
-	return s;
 }
 
-static inline void kseq2bseq1(const kseq_t *ks, bseq1_t *s)
+static inline void kseq2bseq1(const kseq_t *ks, bseq1_t *s, int copy_comment)
 { // TODO: it would be better to allocate one chunk of memory, but probably it does not matter in practice
-	s->name = dupkstring(&ks->name, 1);
-	s->comment = dupkstring(&ks->comment, 0);
-	s->seq = dupkstring(&ks->seq, 1);
-	s->qual = dupkstring(&ks->qual, 0);
+	dupkstring(&ks->name, 1, &s->name, &s->m_name);
+	if (copy_comment) dupkstring(&ks->comment, 0, &s->comment, &s->m_comment);
+	dupkstring(&ks->seq, 1, &s->seq, &s->m_seq);
+	dupkstring(&ks->qual, 0, &s->qual, &s->m_qual);
 	s->l_seq = ks->seq.l;
 }
 
-bseq1_t *bseq_read(int chunk_size, int *n_, void *ks1_, void *ks2_)
+typedef struct {
+    kseq_t *ks;
+    bseq1_t *seq;
+    int start_pos;
+    int n_bound;
+	int copy_comment;
+    int ret_n;
+    int ret_size;
+	int ret_status;
+	int chunk_size;
+} read_data_t;
+
+static void *thread_bseq_read(void *data) {
+    read_data_t *d = (read_data_t*) data;
+    kseq_t *ks = d->ks;
+    bseq1_t *seqs = d->seq;
+	int copy_comment = d->copy_comment;
+	int chunk_size = d->chunk_size;
+	int cur_n = 0, cur_pos = d->start_pos, size = 0;
+	int ret_status = 1;
+
+	while (cur_n < d->n_bound && (ret_status = kseq_read(ks)) >= 0) {
+		trim_readno(&ks->name);
+		kseq2bseq1(ks, seqs + cur_pos, copy_comment);
+		seqs[cur_pos].id = cur_pos;
+		size += seqs[cur_pos].l_seq;
+        cur_pos += 2; cur_n += 1;
+		if (size >= chunk_size) break;
+	}
+    d->ret_n = cur_n; d->ret_size = size; d->ret_status = ret_status;
+    return 0;
+}
+
+#define READ_ONE_SEQ(ks)                    \
+	trim_readno(&ks->name);                 \
+	kseq2bseq1(ks, &seqs[n], copy_comment); \
+	seqs[n].id = n;                         \
+	size += seqs[n++].l_seq;
+
+// multi thread reading input seqs
+void bseq_read_pe_mt(int chunk_size, int *n_, void *ks1_, void *ks2_, int copy_comment, int64_t *size_, int *m_, bseq1_t **seqs_ptr)
 {
+	kseq_t *ks = (kseq_t *)ks1_, *ks2 = (kseq_t *)ks2_;
+	int size = 0, m = *m_, n = 0;
+	bseq1_t *seqs = *seqs_ptr;
+	read_data_t d[2];
+	pthread_t tid[2];
+
+	if (m == 0) { // 还没开辟空间，要初始化
+		seqs = calloc(20, sizeof(bseq1_t)); // 先读取20个reads，根据reads的长度和chunk size决定要读取多少条reads
+		int ks1_ret = 0, ks2_ret = 0;
+		int i = 10;
+		while (i-- > 0) {
+			ks1_ret = kseq_read(ks);
+			if (ks1_ret < 0) break;
+			ks2_ret = kseq_read(ks2);
+			if (ks2_ret < 0) {
+				fprintf(stderr, "[W::%s] the 2nd file has fewer sequences.\n", __func__);
+				break;
+			}
+			READ_ONE_SEQ(ks);
+			READ_ONE_SEQ(ks2);
+		}
+		if (ks1_ret < 0 || ks2_ret < 0) {
+			if (size == 0 && kseq_read(ks2) >= 0) { // test if the 2nd file is finished
+				fprintf(stderr, "[W::%s] the 1st file has fewer sequences.\n", __func__);
+			}
+			*n_ = n; *seqs_ptr = seqs;
+			return;
+		}
+		// 重新开辟空间
+		m = (chunk_size + size / 10 - 1) / (size / 10) * 2;
+		*m_ = m;
+		seqs = realloc(seqs, m * sizeof(bseq1_t));
+		memset(seqs + n, 0, sizeof(bseq1_t));
+		*seqs_ptr = seqs;
+	}
+
+	d[0].copy_comment = copy_comment; d[1].copy_comment = copy_comment;
+    d[0].ks = ks ; d[0].seq = &seqs[0]; d[0].n_bound = (m >> 1) - (n>>1); d[0].start_pos = n;
+    d[1].ks = ks2; d[1].seq = &seqs[0]; d[1].n_bound = (m >> 1) - (n>>1); d[1].start_pos = n+1;
+	d[0].chunk_size = d[1].chunk_size = (chunk_size + 1) >> 1;
+
+	pthread_create(&tid[0], 0, thread_bseq_read, &d[0]);
+    pthread_create(&tid[1], 0, thread_bseq_read, &d[1]);
+    pthread_join(tid[0], 0); pthread_join(tid[1], 0);
+
+	size += d[0].ret_size + d[1].ret_size;
+	n += d[0].ret_n + d[1].ret_n;
+
+	if (size == 0 && kseq_read(ks2) >= 0) { // test if the 2nd file is finished
+		fprintf(stderr, "[W::%s] the 1st file has fewer sequences.\n", __func__);
+	} else if (size < chunk_size && d[0].ret_status > 0 && d[1].ret_status > 0) {
+		while (kseq_read(ks) >= 0) {
+			if (ks2 && kseq_read(ks2) < 0) { // the 2nd file has fewer reads
+				fprintf(stderr, "[W::%s] the 2nd file has fewer sequences.\n", __func__);
+				break;
+			}
+			if (n >= m) {
+				m = m? m<<1 : 256;
+				seqs = realloc(seqs, m * sizeof(bseq1_t));
+				memset(seqs + n, 0, (m-n) * sizeof(bseq1_t));
+			}
+			READ_ONE_SEQ(ks);
+			if (ks2) {
+				READ_ONE_SEQ(ks2);
+			}
+			if (size >= chunk_size && (n&1) == 0) break;
+		}
+		if (size == 0) { // test if the 2nd file is finished
+			if (ks2 && kseq_read(ks2) >= 0) fprintf(stderr, "[W::%s] the 1st file has fewer sequences.\n", __func__);
+		}
+	}
+
+	*n_ = n; *size_ = size;
+	if (m > *m_) *m_ = m;
+	*seqs_ptr = seqs;
+}
+
+void bseq_read(int chunk_size, int *n_, void *ks1_, void *ks2_, int copy_comment, int64_t *size_, int *m_, bseq1_t **seqs_ptr)
+{
+#ifdef USE_MT_READ
+	if (ks2_) return bseq_read_pe_mt(chunk_size, n_, ks1_, ks2_, copy_comment, size_, m_, seqs_ptr);
+#endif
 	kseq_t *ks = (kseq_t*)ks1_, *ks2 = (kseq_t*)ks2_;
 	int size = 0, m, n;
-	bseq1_t *seqs;
-	m = n = 0; seqs = 0;
+	bseq1_t *seqs = *seqs_ptr;
+	n = 0; m = *m_;
 	while (kseq_read(ks) >= 0) {
 		if (ks2 && kseq_read(ks2) < 0) { // the 2nd file has fewer reads
 			fprintf(stderr, "[W::%s] the 2nd file has fewer sequences.\n", __func__);
@@ -91,16 +221,11 @@ bseq1_t *bseq_read(int chunk_size, int *n_, void *ks1_, void *ks2_)
 		if (n >= m) {
 			m = m? m<<1 : 256;
 			seqs = realloc(seqs, m * sizeof(bseq1_t));
+			memset(seqs + n, 0, (m-n) * sizeof(bseq1_t));
 		}
-		trim_readno(&ks->name);
-		kseq2bseq1(ks, &seqs[n]);
-		seqs[n].id = n;
-		size += seqs[n++].l_seq;
+		READ_ONE_SEQ(ks);
 		if (ks2) {
-			trim_readno(&ks2->name);
-			kseq2bseq1(ks2, &seqs[n]);
-			seqs[n].id = n;
-			size += seqs[n++].l_seq;
+			READ_ONE_SEQ(ks2);
 		}
 		if (size >= chunk_size && (n&1) == 0) break;
 	}
@@ -108,8 +233,9 @@ bseq1_t *bseq_read(int chunk_size, int *n_, void *ks1_, void *ks2_)
 		if (ks2 && kseq_read(ks2) >= 0)
 			fprintf(stderr, "[W::%s] the 1st file has fewer sequences.\n", __func__);
 	}
-	*n_ = n;
-	return seqs;
+	*n_ = n; *size_ = size;
+	if (m > *m_) *m_ = m;
+	*seqs_ptr = seqs;
 }
 
 void bseq_classify(int n, bseq1_t *seqs, int m[2], bseq1_t *sep[2])
@@ -339,9 +465,10 @@ bwaidx_t *bwa_idx_load_from_disk(const char *hint, int which)
 		return 0;
 	}
 	idx = calloc(1, sizeof(bwaidx_t));
-	if (which & BWA_IDX_BWT) idx->bwt = bwa_idx_load_bwt(hint);
+
 	if (which & BWA_IDX_BWT)  idx->fmt = bwa_idx_load_fmt(hint);
-	idx->bwt->kmer_hash = idx->fmt->kmer_hash;
+	//if (which & BWA_IDX_BWT) idx->bwt = bwa_idx_load_bwt(hint);
+	//idx->bwt->kmer_hash = idx->fmt->kmer_hash;
 	
 	if (which & BWA_IDX_BNS)
 	{
diff --git a/bwa.h b/bwa.h
index aa155b6..5e125a8 100644
--- a/bwa.h
+++ b/bwa.h
@@ -29,6 +29,7 @@
 
 #include <stdint.h>
 #include "bntseq.h"
+#include "kstring.h"
 #include "bwt.h"
 #include "fmt_idx.h"
 
@@ -59,7 +60,9 @@ typedef struct {
 
 typedef struct {
 	int l_seq, id;
-	char *name, *comment, *seq, *qual, *sam;
+	int m_name, m_comment, m_seq, m_qual;
+	char *name, *comment, *seq, *qual;
+	kstring_t sam;
 } bseq1_t;
 
 extern int bwa_verbose, bwa_dbg;
@@ -69,7 +72,8 @@ extern char bwa_rg_id[256];
 extern "C" {
 #endif
 
-	bseq1_t *bseq_read(int chunk_size, int *n_, void *ks1_, void *ks2_);
+	//bseq1_t *bseq_read(int chunk_size, int *n_, void *ks1_, void *ks2_);
+	void bseq_read(int chunk_size, int *n_, void *ks1_, void *ks2_, int copy_comment, int64_t *size_, int *m_, bseq1_t **seqs_ptr);
 	void bseq_classify(int n, bseq1_t *seqs, int m[2], bseq1_t *sep[2]);
 
 	void bwa_fill_scmat(int a, int b, int8_t mat[25]);
diff --git a/bwamem.c b/bwamem.c
index 3a264ff..1a407e7 100644
--- a/bwamem.c
+++ b/bwamem.c
@@ -117,30 +117,7 @@ mem_opt_t *mem_opt_init()
 #define intv_lt(a, b) ((a).info < (b).info)
 KSORT_INIT(mem_intv, bwtintv_t, intv_lt)
 
-typedef struct {
-	bwtintv_v mem, mem1, *tmpv[2];
-} smem_aux_t;
-
-static smem_aux_t *smem_aux_init()
-{
-	smem_aux_t *a;
-	a = calloc(1, sizeof(smem_aux_t));
-	a->tmpv[0] = calloc(1, sizeof(bwtintv_v));
-	a->tmpv[1] = calloc(1, sizeof(bwtintv_v));
-	return a;
-}
-
-static void smem_aux_destroy(smem_aux_t *a)
-{	
-	free(a->tmpv[0]->a); free(a->tmpv[0]);
-	free(a->tmpv[1]->a); free(a->tmpv[1]);
-	free(a->mem.a); free(a->mem1.a);
-	free(a);
-}
-
-#define USE_FMT 1
-
-static void mem_collect_intv(const mem_opt_t *opt, const bwt_t *bwt, const FMTIndex *fmt, int len, const uint8_t *seq, smem_aux_t *a)
+static void mem_collect_intv(const mem_opt_t *opt, const FMTIndex *fmt, int len, const uint8_t *seq, smem_aux_t *a)
 {
 	int i, k, x = 0, old_n;
 	int start_width = 1;
@@ -149,131 +126,79 @@ static void mem_collect_intv(const mem_opt_t *opt, const bwt_t *bwt, const FMTIn
 	int start_N_num = 0, start_flag = 1;
 	a->mem.n = 0;
 
-	// first pass: find all SMEMs
-	fprintf(fp1, "seq: %ld\n", dn++);
-	// fprintf(stderr, "seq: %ld\n", dn++);
-	// dn ++;
-	// goto third_seed;
-
+#ifdef SHOW_PERF
+	int64_t tmp_time = realtime_msec();
+#endif
+	// 1. first pass: find all SMEMs
 	while (x < len) {
 		if (seq[x] < 4) {
 			start_flag = 0;
-#ifdef SHOW_PERF
-			int64_t tmp_time = realtime_msec();
-#endif
-#if USE_FMT
 			x = fmt_smem(fmt, len, seq, x, start_width, opt->min_seed_len, &a->mem1, a->tmpv[0]);
-#else
-			x = bwt_smem1(bwt, len, seq, x, start_width, &a->mem1, a->tmpv);
-#endif
-#ifdef SHOW_PERF
-			tmp_time = realtime_msec() - tmp_time;
-			__sync_fetch_and_add(&time_seed_1, tmp_time);
-#endif
-			s1n += a->mem1.n;
 			for (i = 0; i < a->mem1.n; ++i) {
 				bwtintv_t *p = &a->mem1.a[i];
-				//fprintf(fp1, "%ld %ld %d\n", p->x[2], p->info >> 32, (uint32_t)p->info);
-				//fprintf(fp1, "%ld %ld %ld %ld %d\n", p->x[0], p->x[1], p->x[2], p->info >> 32, (uint32_t)p->info);
-				//fprintf(stderr, "%ld %ld %ld %ld %d\n", p->x[0], p->x[1], p->x[2], p->info >> 32, (uint32_t)p->info);
 				int slen = (uint32_t)p->info - (p->info >> 32); // seed length
-				s1l += slen;
-				max_seed_len = fmax(max_seed_len, slen);
+				max_seed_len = MAX(max_seed_len, slen);
 				if (slen >= opt->min_seed_len) {
-					//fprintf(fp1, "%ld %ld %d\n", p->x[2], p->info >> 32, (uint32_t)p->info);
 					kv_push(bwtintv_t, a->mem, *p);
 				}
 			}
 		} else {
 			++x;
-			if (start_flag)
-				++start_N_num;
+			if (start_flag) ++start_N_num;
 		}
 	}
-	// second pass: find MEMs inside a long SMEM
-	//if (max_seed_len == len - start_N_num)
-	//	goto collect_intv_end;
-	//goto third_seed;
+#ifdef SHOW_PERF
+	tmp_time = realtime_msec() - tmp_time;
+	__sync_fetch_and_add(&time_seed_1, tmp_time);
+	tmp_time = realtime_msec();
+#endif
 
+#ifdef FILTER_FULL_MATCH
+	if (max_seed_len == len - start_N_num) goto collect_intv_end;
+#endif
+
+	// 2. second pass: find MEMs inside a long SMEM
 	old_n = a->mem.n;
 	for (k = 0; k < old_n; ++k) {
 		bwtintv_t *p = &a->mem.a[k];
 		int start = p->info>>32, end = (int32_t)p->info;
 		if (end - start < split_len || p->x[2] > opt->split_width) continue;
-#ifdef SHOW_PERF
-		int64_t tmp_time = realtime_msec();
-#endif
-#if USE_FMT
 		fmt_smem(fmt, len, seq, (start + end) >> 1, p->x[2] + 1, opt->min_seed_len, &a->mem1, a->tmpv[0]);
-#else
-		bwt_smem1(bwt, len, seq, (start + end) >> 1, p->x[2] + 1, &a->mem1, a->tmpv);
-#endif
-#ifdef SHOW_PERF
-		tmp_time = realtime_msec() - tmp_time;
-		__sync_fetch_and_add(&time_seed_2, tmp_time);
-#endif
-		s2n += a->mem1.n;
-
 		for (i = 0; i < a->mem1.n; ++i) {
 			bwtintv_t *p = &a->mem1.a[i];
-			//fprintf(fp1, "%ld %ld %d\n", p->x[2], p->info >> 32, (uint32_t)p->info);
-			// fprintf(fp1, "%ld %ld %ld %ld %d\n", p->x[0], p->x[1], p->x[2], p->info >> 32, (uint32_t)p->info);
-			// fprintf(stderr, "%ld %ld %ld %ld %d\n", p->x[0], p->x[1], p->x[2], p->info >> 32, (uint32_t)p->info);
 			int slen = (uint32_t)p->info - (p->info >> 32);
-			s2l += slen;
 			if (slen >= opt->min_seed_len) {
-				g_num_smem2 += 1;
-				fprintf(fp1, "%ld %ld %d\n", p->x[2], p->info >> 32, (uint32_t)p->info);
 				kv_push(bwtintv_t, a->mem, a->mem1.a[i]);
 			}
 		}
 	}
-	//if (max_seed_len == len - start_N_num)
-	//	goto collect_intv_end;
-	//goto collect_intv_end;
-third_seed:
-	// third pass: LAST-like
+#ifdef SHOW_PERF
+	tmp_time = realtime_msec() - tmp_time;
+	__sync_fetch_and_add(&time_seed_2, tmp_time);
+	tmp_time = realtime_msec();
+#endif
+	// 3. third pass: LAST-like
 	if (opt->max_mem_intv > 0) {
 		x = 0;
 		while (x < len) {
 			if (seq[x] < 4) {
-				if (1) {
-					bwtintv_t m;
-#ifdef SHOW_PERF
-					int64_t tmp_time = realtime_msec();
-#endif
-
-#if USE_FMT
-					x = fmt_seed_strategy1(fmt, len, seq, x, opt->min_seed_len, opt->max_mem_intv, &m);
-#else
-					x = bwt_seed_strategy1(bwt, len, seq, x, opt->min_seed_len, opt->max_mem_intv, &m);
-#endif
-#ifdef SHOW_PERF
-					tmp_time = realtime_msec() - tmp_time;
-					__sync_fetch_and_add(&time_seed_3, tmp_time);
-#endif
-					s3n += 1;
-					s3l += (uint32_t)m.info - (m.info >> 32);
-					// bwtintv_t *p = &m;
-					// fprintf(fp1, "%ld %ld %ld %ld %d\n", p->x[0], p->x[1], p->x[2], p->info >> 32, (uint32_t)p->info);
-
-					if (m.x[2] > 0) {
-						kv_push(bwtintv_t, a->mem, m);
-						//bwtintv_t *p = &m;
-						//fprintf(fp1, "%ld %ld %d\n", p->x[2], p->info >> 32, (uint32_t)p->info);
-						//fprintf(fp1, "%ld %ld %ld %ld %d\n", p->x[0], p->x[1], p->x[2], p->info >> 32, (uint32_t)p->info);
-					}
-				} else { // for now, we never come to this block which is slower
-					x = bwt_smem1a(bwt, len, seq, x, start_width, opt->max_mem_intv, &a->mem1, a->tmpv);
-					for (i = 0; i < a->mem1.n; ++i)
-						kv_push(bwtintv_t, a->mem, a->mem1.a[i]);
+				bwtintv_t m;
+				x = fmt_seed_strategy1(fmt, len, seq, x, opt->min_seed_len, opt->max_mem_intv, &m);
+				if (m.x[2] > 0) {
+					kv_push(bwtintv_t, a->mem, m);
 				}
 			} else ++x;
 		}
 	}
+#ifdef SHOW_PERF
+	tmp_time = realtime_msec() - tmp_time;
+	__sync_fetch_and_add(&time_seed_3, tmp_time);
+#endif
 
-//collect_intv_end:
-	// sort
+#ifdef FILTER_FULL_MATCH
+collect_intv_end:
+#endif
+	//  sort
 	ks_introsort(mem_intv, a->mem.n, a->mem.a);
 }
 
@@ -281,22 +206,6 @@ third_seed:
  * Chaining *
  ************/
 
-typedef struct {
-	int64_t rbeg;
-	int32_t qbeg, len;
-	int score;
-} mem_seed_t; // unaligned memory
-
-typedef struct {
-	int n, m, first, rid;
-	uint32_t w:29, kept:2, is_alt:1;
-	float frac_rep;
-	int64_t pos;
-	mem_seed_t *seeds;
-} mem_chain_t;
-
-typedef struct { size_t n, m; mem_chain_t *a;  } mem_chain_v;
-
 #include "kbtree.h"
 
 #define chain_cmp(a, b) (((b).pos < (a).pos) - ((a).pos < (b).pos))
@@ -364,7 +273,7 @@ void mem_print_chain(const bntseq_t *bns, mem_chain_v *chn)
 	}
 }
 
-mem_chain_v mem_chain(const mem_opt_t *opt, const bwt_t *bwt, const FMTIndex *fmt, const bntseq_t *bns, int len, const uint8_t *seq, void *buf)
+mem_chain_v mem_chain(const mem_opt_t *opt, const FMTIndex *fmt, const bntseq_t *bns, int len, const uint8_t *seq, void *buf)
 {
 	int i, b, e, l_rep;
 	int64_t l_pac = bns->l_pac;
@@ -376,8 +285,37 @@ mem_chain_v mem_chain(const mem_opt_t *opt, const bwt_t *bwt, const FMTIndex *fm
 	if (len < opt->min_seed_len) return chain; // if the query is shorter than the seed length, no match
 	tree = kb_init(chn, KB_DEFAULT_SIZE);
 
-	aux = buf? (smem_aux_t*)buf : smem_aux_init();
-	mem_collect_intv(opt, bwt, fmt, len, seq, aux);
+	aux = (smem_aux_t*)buf;
+	mem_collect_intv(opt, fmt, len, seq, aux);
+
+#define CHECK_ADD_CHAIN(tmp, lower, upper)                         \
+	int rid, to_add = 0;                                           \
+	mem_chain_t tmp, *lower, *upper;                               \
+	tmp.pos = s.rbeg;                                              \
+	s.qbeg = p->info >> 32;                                        \
+	s.score = s.len = slen;                                        \
+	rid = bns_intv2rid(bns, s.rbeg, s.rbeg + s.len);               \
+	if (rid < 0)                                                   \
+		continue;                                                  \
+	if (kb_size(tree))                                             \
+	{                                                              \
+		kb_intervalp(chn, tree, &tmp, &lower, &upper);             \
+		if (!lower || !test_and_merge(opt, l_pac, lower, &s, rid)) \
+			to_add = 1;                                            \
+	}                                                              \
+	else                                                           \
+		to_add = 1;                                                \
+	if (to_add)                                                    \
+	{                                                              \
+		tmp.n = 1;                                                 \
+		tmp.m = 4;                                                 \
+		tmp.seeds = calloc(tmp.m, sizeof(mem_seed_t));             \
+		tmp.seeds[0] = s;                                          \
+		tmp.rid = rid;                                             \
+		tmp.is_alt = !!bns->anns[rid].is_alt;                      \
+		kb_putp(chn, tree, &tmp);                                  \
+	}
+
 	for (i = 0, b = e = l_rep = 0; i < aux->mem.n; ++i) { // compute frac_rep
 		bwtintv_t *p = &aux->mem.a[i];
 		int sb = (p->info>>32), se = (uint32_t)p->info;
@@ -390,92 +328,28 @@ mem_chain_v mem_chain(const mem_opt_t *opt, const bwt_t *bwt, const FMTIndex *fm
 		bwtintv_t *p = &aux->mem.a[i];
 		int step, count, slen = (uint32_t)p->info - (p->info>>32); // seed length
 		int64_t k;
-		// if (slen < opt->min_seed_len) continue; // ignore if too short or too repetitive
-		//if (0) {
+
 		if (p->num_match > 0) {
-			//continue;
-			for (k = 0; k < p->num_match; ++k) {
-				mem_chain_t tmp, *lower, *upper;
-				mem_seed_t s;
-				int rid, to_add = 0;
-				s.rbeg = p->rm[k].rs;
-				if (p->rm[k].reverse) {
-					s.rbeg = (fmt->l_pac << 1) - 1 - s.rbeg;
-				}
-				tmp.pos = s.rbeg;
-				s.qbeg = p->info >> 32;
-				s.score = s.len = slen;
-				rid = bns_intv2rid(bns, s.rbeg, s.rbeg + s.len);
-				if (rid < 0) continue;
-				if (kb_size(tree))
-				{
-					kb_intervalp(chn, tree, &tmp, &lower, &upper); // find the closest chain
-					if (!lower || !test_and_merge(opt, l_pac, lower, &s, rid))
-						to_add = 1;
-				}
-				else
-					to_add = 1;
-				if (to_add)
-				{ // add the seed as a new chain
-					tmp.n = 1;
-					tmp.m = 4;
-					tmp.seeds = calloc(tmp.m, sizeof(mem_seed_t));
-					tmp.seeds[0] = s;
-					tmp.rid = rid;
-					tmp.is_alt = !!bns->anns[rid].is_alt;
-					kb_putp(chn, tree, &tmp);
-				}
-			}
-			continue;
-		}
-		step = p->x[2] > opt->max_occ? p->x[2] / opt->max_occ : 1;
-		for (k = count = 0; k < p->x[2] && count < opt->max_occ; k += step, ++count) {
-			mem_chain_t tmp, *lower, *upper;
 			mem_seed_t s;
-			int rid, to_add = 0;
+			s.rbeg = p->rm[0].rs;
+			if (p->rm[0].reverse) s.rbeg = (fmt->l_pac << 1) - 1 - s.rbeg;
+			CHECK_ADD_CHAIN(tmp, lower, upper);
+		} else {
+			step = p->x[2] > opt->max_occ? p->x[2] / opt->max_occ : 1;
+			for (k = count = 0; k < p->x[2] && count < opt->max_occ; k += step, ++count) {
+				mem_seed_t s;
 #ifdef SHOW_PERF
-			int64_t tmp_time = realtime_msec();
-#endif
-#if USE_FMT
-			s.rbeg = tmp.pos = fmt_sa(fmt, p->x[0] + k);
-			// uint64_t tpos = bwt_sa(bwt, p->x[0] + k);
-			// if (s.rbeg != tpos) {
-			// 	fprintf(stderr, "diff: %ld, %ld %ld\n", p->x[0] + k, tmp.pos, tpos);
-			// }
-#else
-			s.rbeg = tmp.pos = bwt_sa(bwt, p->x[0] + k); // this is the base coordinate in the forward-reverse reference
+				int64_t tmp_time = realtime_msec();
 #endif
+				s.rbeg = fmt_sa(fmt, p->x[0] + k);
 #ifdef SHOW_PERF
-			tmp_time = realtime_msec() - tmp_time;
-			__sync_fetch_and_add(&time_bwt_sa, tmp_time);
-			__sync_fetch_and_add(&num_sa, 1);
+				tmp_time = realtime_msec() - tmp_time;
+				__sync_fetch_and_add(&time_bwt_sa, tmp_time);
 #endif
-			s.qbeg = p->info >> 32;
-			s.score= s.len = slen;
-#ifdef SHOW_PERF
-			tmp_time = realtime_msec();
-#endif
-			rid = bns_intv2rid(bns, s.rbeg, s.rbeg + s.len);
-#ifdef SHOW_PERF
-			tmp_time = realtime_msec() - tmp_time;
-			__sync_fetch_and_add(&time_bns, tmp_time);
-#endif
-			if (rid < 0) continue; // bridging multiple reference sequences or the forward-reverse boundary; TODO: split the seed; don't discard it!!!
-			if (kb_size(tree)) {
-				kb_intervalp(chn, tree, &tmp, &lower, &upper); // find the closest chain
-				if (!lower || !test_and_merge(opt, l_pac, lower, &s, rid)) to_add = 1;
-			} else to_add = 1;
-			if (to_add) { // add the seed as a new chain
-				tmp.n = 1; tmp.m = 4;
-				tmp.seeds = calloc(tmp.m, sizeof(mem_seed_t));
-				tmp.seeds[0] = s;
-				tmp.rid = rid;
-				tmp.is_alt = !!bns->anns[rid].is_alt;
-				kb_putp(chn, tree, &tmp);
+				CHECK_ADD_CHAIN(tmp, lower, upper);
 			}
 		}
 	}
-	if (buf == 0) smem_aux_destroy(aux);
 
 	kv_resize(mem_chain_t, chain, kb_size(tree));
 
@@ -485,8 +359,8 @@ mem_chain_v mem_chain(const mem_opt_t *opt, const bwt_t *bwt, const FMTIndex *fm
 
 	for (i = 0; i < chain.n; ++i) chain.a[i].frac_rep = (float)l_rep / len;
 	if (bwa_verbose >= 4) printf("* fraction of repetitive seeds: %.3f\n", (float)l_rep / len);
-
 	kb_destroy(chn, tree);
+
 	return chain;
 }
 
@@ -744,7 +618,7 @@ int mem_mark_primary_se(const mem_opt_t *opt, int n, mem_alnreg_t *a, int64_t id
 #define MEM_MINSC_COEF 5.5f
 #define MEM_SEEDSW_COEF 0.05f
 
-int mem_seed_sw(const mem_opt_t *opt, const bntseq_t *bns, const uint8_t *pac, int l_query, const uint8_t *query, const mem_seed_t *s)
+int mem_seed_sw(const mem_opt_t *opt, const bntseq_t *bns, const uint8_t *pac, int l_query, const uint8_t *query, const mem_seed_t *s, buf_t *buf)
 {
 	int qb, qe, rid;
 	int64_t rb, re, mid, l_pac = bns->l_pac;
@@ -766,12 +640,14 @@ int mem_seed_sw(const mem_opt_t *opt, const bntseq_t *bns, const uint8_t *pac, i
 	if (qe - qb >= MEM_SHORT_LEN || re - rb >= MEM_SHORT_LEN) return -1; // the seed seems good enough; no need to do SW
 
 	rseq = bns_fetch_seq(bns, pac, &rb, mid, &re, &rid);
+	//bns_fetch_seq_no_alloc(bns, pac, &rb, mid, &re, &rid, &buf->m, &buf->addr); rseq = buf->addr;
+
 	x = ksw_align2(qe - qb, (uint8_t*)query + qb, re - rb, rseq, 5, opt->mat, opt->o_del, opt->e_del, opt->o_ins, opt->e_ins, KSW_XSTART, 0);
 	free(rseq);
 	return x.score;
 }
 
-void mem_flt_chained_seeds(const mem_opt_t *opt, const bntseq_t *bns, const uint8_t *pac, int l_query, const uint8_t *query, int n_chn, mem_chain_t *a)
+void mem_flt_chained_seeds(const mem_opt_t *opt, const bntseq_t *bns, const uint8_t *pac, int l_query, const uint8_t *query, int n_chn, mem_chain_t *a, buf_t *buf)
 {
 	double min_l = opt->min_chain_weight? MEM_HSP_COEF * opt->min_chain_weight : MEM_MINSC_COEF * log(l_query);
 	int i, j, k, min_HSP_score = (int)(opt->a * min_l + .499);
@@ -780,7 +656,7 @@ void mem_flt_chained_seeds(const mem_opt_t *opt, const bntseq_t *bns, const uint
 		mem_chain_t *c = &a[i];
 		for (j = k = 0; j < c->n; ++j) {
 			mem_seed_t *s = &c->seeds[j];
-			s->score = mem_seed_sw(opt, bns, pac, l_query, query, s);
+			s->score = mem_seed_sw(opt, bns, pac, l_query, query, s, buf);
 			if (s->score < 0 || s->score >= min_HSP_score) {
 				s->score = s->score < 0? s->len * opt->a : s->score;
 				c->seeds[k++] = *s;
@@ -805,13 +681,14 @@ static inline int cal_max_gap(const mem_opt_t *opt, int qlen)
 
 #define MAX_BAND_TRY  2
 
-void mem_chain2aln(const mem_opt_t *opt, const bntseq_t *bns, const uint8_t *pac, int l_query, const uint8_t *query, const mem_chain_t *c, mem_alnreg_v *av)
+void mem_chain2aln(const mem_opt_t *opt, const bntseq_t *bns, const uint8_t *pac, int l_query, const uint8_t *query, const mem_chain_t *c, mem_alnreg_v *av, void *buf)
 {
 	int i, k, rid, max_off[2], aw[2]; // aw: actual bandwidth used in extension
 	int64_t l_pac = bns->l_pac, rmax[2], tmp, max = 0;
 	const mem_seed_t *s;
 	uint8_t *rseq = 0;
 	uint64_t *srt;
+	smem_aux_t *aux = (smem_aux_t*)buf;
 
 	if (c->n == 0) return;
 	// get the max possible span
@@ -833,6 +710,8 @@ void mem_chain2aln(const mem_opt_t *opt, const bntseq_t *bns, const uint8_t *pac
 	}
 	// retrieve the reference sequence
 	rseq = bns_fetch_seq(bns, pac, &rmax[0], c->seeds[0].rbeg, &rmax[1], &rid);
+	//bns_fetch_seq_no_alloc(bns, pac, &rmax[0], c->seeds[0].rbeg, &rmax[1], &rid, &aux->seq_buf->m, &aux->seq_buf->addr); rseq = aux->seq_buf->addr;
+
 	assert(c->rid == rid);
 
 	srt = malloc(c->n * 8);
@@ -889,25 +768,31 @@ void mem_chain2aln(const mem_opt_t *opt, const bntseq_t *bns, const uint8_t *pac
 
 		if (bwa_verbose >= 4) err_printf("** ---> Extending from seed(%d) [%ld;%ld,%ld] @ %s <---\n", k, (long)s->len, (long)s->qbeg, (long)s->rbeg, bns->anns[c->rid].name);
 		if (s->qbeg) { // left extension
-			uint8_t *rs, *qs;
 			int qle, tle, gtle, gscore;
+			tmp = s->rbeg - rmax[0];
+#ifndef USE_AVX2
+			uint8_t *rs, *qs;
 			qs = malloc(s->qbeg);
 			for (i = 0; i < s->qbeg; ++i) qs[i] = query[s->qbeg - 1 - i];
-			tmp = s->rbeg - rmax[0];
 			rs = malloc(tmp);
 			for (i = 0; i < tmp; ++i) rs[i] = rseq[tmp - 1 - i];
+#endif
 			for (i = 0; i < MAX_BAND_TRY; ++i) {
 				int prev = a->score;
 				aw[0] = opt->w << i;
 				if (bwa_verbose >= 4) {
 					int j;
-					printf("*** Left ref:   "); for (j = 0; j < tmp; ++j) putchar("ACGTN"[(int)rs[j]]); putchar('\n');
-					printf("*** Left query: "); for (j = 0; j < s->qbeg; ++j) putchar("ACGTN"[(int)qs[j]]); putchar('\n');
+					printf("*** Left ref:   "); for (j = 0; j < tmp; ++j) putchar("ACGTN"[(int)rseq[tmp - 1 - j]]); putchar('\n');
+					printf("*** Left query: "); for (j = 0; j < s->qbeg; ++j) putchar("ACGTN"[(int)query[s->qbeg - 1 - j]]); putchar('\n');
 				}
 #ifdef SHOW_PERF
 				int64_t tmp_time = realtime_msec();
 #endif
-				a->score = ksw_extend2(s->qbeg, qs, tmp, rs, 5, opt->mat, opt->o_del, opt->e_del, opt->o_ins, opt->e_ins, aw[0], opt->pen_clip5, opt->zdrop, s->len * opt->a, &qle, &tle, &gtle, &gscore, &max_off[0]);
+#ifndef USE_AVX2
+				a->score = ksw_extend2(s->qbeg, qs, tmp, rs, 5, opt->mat, opt->o_del, opt->e_del, opt->o_ins, opt->e_ins, aw[0], opt->pen_clip5, opt->zdrop, s->len * opt->a, &qle, &tle, &gtle, &gscore, &max_off[0], aux->sw_buf);
+#else
+				a->score = ksw_extend2_avx2(s->qbeg, query, tmp, rseq, 1, 5, opt->mat, opt->o_del, opt->e_del, opt->o_ins, opt->e_ins, opt->a, opt->b, aw[0], opt->pen_clip5, opt->zdrop, s->len * opt->a, &qle, &tle, &gtle, &gscore, &max_off[0], aux->sw_buf);
+#endif
 #ifdef SHOW_PERF
 				tmp_time = realtime_msec() - tmp_time;
 				__sync_fetch_and_add(&time_ksw_extend2, tmp_time);
@@ -923,7 +808,9 @@ void mem_chain2aln(const mem_opt_t *opt, const bntseq_t *bns, const uint8_t *pac
 				a->qb = 0, a->rb = s->rbeg - gtle;
 				a->truesc = gscore;
 			}
+#ifndef USE_AVX2
 			free(qs); free(rs);
+#endif
 		} else a->score = a->truesc = s->len * opt->a, a->qb = 0, a->rb = s->rbeg;
 
 		if (s->qbeg + s->len != l_query) { // right extension
@@ -942,7 +829,11 @@ void mem_chain2aln(const mem_opt_t *opt, const bntseq_t *bns, const uint8_t *pac
 #ifdef SHOW_PERF
 				int64_t tmp_time = realtime_msec();
 #endif
-				a->score = ksw_extend2(l_query - qe, query + qe, rmax[1] - rmax[0] - re, rseq + re, 5, opt->mat, opt->o_del, opt->e_del, opt->o_ins, opt->e_ins, aw[1], opt->pen_clip3, opt->zdrop, sc0, &qle, &tle, &gtle, &gscore, &max_off[1]);
+#ifndef USE_AVX2
+				a->score = ksw_extend2(l_query - qe, query + qe, rmax[1] - rmax[0] - re, rseq + re, 5, opt->mat, opt->o_del, opt->e_del, opt->o_ins, opt->e_ins, aw[1], opt->pen_clip3, opt->zdrop, sc0, &qle, &tle, &gtle, &gscore, &max_off[1], aux->sw_buf);
+#else
+				a->score = ksw_extend2_avx2(l_query - qe, query + qe, rmax[1] - rmax[0] - re, rseq + re, 0, 5, opt->mat, opt->o_del, opt->e_del, opt->o_ins, opt->e_ins, opt->a, opt->b, aw[1], opt->pen_clip3, opt->zdrop, sc0, &qle, &tle, &gtle, &gscore, &max_off[1], aux->sw_buf);
+#endif
 #ifdef SHOW_PERF
 				tmp_time = realtime_msec() - tmp_time;
 				__sync_fetch_and_add(&time_ksw_extend2, tmp_time);
@@ -972,7 +863,8 @@ void mem_chain2aln(const mem_opt_t *opt, const bntseq_t *bns, const uint8_t *pac
 
 		a->frac_rep = c->frac_rep;
 	}
-	free(srt); free(rseq);
+	free(srt);
+	free(rseq);
 }
 
 /*****************************
@@ -1197,7 +1089,7 @@ void mem_reorder_primary5(int T, mem_alnreg_v *a)
 void mem_reg2sam(const mem_opt_t *opt, const bntseq_t *bns, const uint8_t *pac, bseq1_t *s, mem_alnreg_v *a, int extra_flag, const mem_aln_t *m)
 {
 	extern char **mem_gen_alt(const mem_opt_t *opt, const bntseq_t *bns, const uint8_t *pac, mem_alnreg_v *a, int l_query, const char *query);
-	kstring_t str;
+	// kstring_t str;
 	kvec_t(mem_aln_t) aa;
 	int k, l;
 	char **XA = 0;
@@ -1205,7 +1097,8 @@ void mem_reg2sam(const mem_opt_t *opt, const bntseq_t *bns, const uint8_t *pac,
 	if (!(opt->flag & MEM_F_ALL))
 		XA = mem_gen_alt(opt, bns, pac, a, s->l_seq, s->seq);
 	kv_init(aa);
-	str.l = str.m = 0; str.s = 0;
+	// str.l = str.m = 0; str.s = 0;
+	s->sam.l = 0;
 	for (k = l = 0; k < a->n; ++k) {
 		mem_alnreg_t *p = &a->a[k];
 		mem_aln_t *q;
@@ -1228,21 +1121,21 @@ void mem_reg2sam(const mem_opt_t *opt, const bntseq_t *bns, const uint8_t *pac,
 		mem_aln_t t;
 		t = mem_reg2aln(opt, bns, pac, s->l_seq, s->seq, 0);
 		t.flag |= extra_flag;
-		mem_aln2sam(opt, bns, &str, s, 1, &t, 0, m);
+		mem_aln2sam(opt, bns, &s->sam, s, 1, &t, 0, m);
 	} else {
 		for (k = 0; k < aa.n; ++k)
-			mem_aln2sam(opt, bns, &str, s, aa.n, aa.a, k, m);
+			mem_aln2sam(opt, bns, &s->sam, s, aa.n, aa.a, k, m);
 		for (k = 0; k < aa.n; ++k) free(aa.a[k].cigar);
 		free(aa.a);
 	}
-	s->sam = str.s;
+	// s->sam = str.s;
 	if (XA) {
 		for (k = 0; k < a->n; ++k) free(XA[k]);
 		free(XA);
 	}
 }
 
-mem_alnreg_v mem_align1_core(const mem_opt_t *opt, const bwt_t *bwt, const FMTIndex *fmt, const bntseq_t *bns, const uint8_t *pac, int l_seq, char *seq, void *buf)
+mem_alnreg_v mem_align1_core(const mem_opt_t *opt, const FMTIndex *fmt, const bntseq_t *bns, const uint8_t *pac, int l_seq, char *seq, void *buf)
 {
 	int i;
 	mem_chain_v chn;
@@ -1251,16 +1144,16 @@ mem_alnreg_v mem_align1_core(const mem_opt_t *opt, const bwt_t *bwt, const FMTIn
 	for (i = 0; i < l_seq; ++i) // convert to 2-bit encoding if we have not done so
 		seq[i] = seq[i] < 4? seq[i] : nst_nt4_table[(int)seq[i]];
 
-	chn = mem_chain(opt, bwt, fmt, bns, l_seq, (uint8_t*)seq, buf);
+	chn = mem_chain(opt, fmt, bns, l_seq, (uint8_t*)seq, buf);
 	chn.n = mem_chain_flt(opt, chn.n, chn.a);
-	mem_flt_chained_seeds(opt, bns, pac, l_seq, (uint8_t*)seq, chn.n, chn.a);
+	mem_flt_chained_seeds(opt, bns, pac, l_seq, (uint8_t *)seq, chn.n, chn.a, ((smem_aux_t *)buf)->seq_buf);
 	if (bwa_verbose >= 4) mem_print_chain(bns, &chn);
 
 	kv_init(regs);
 	for (i = 0; i < chn.n; ++i) {
 		mem_chain_t *p = &chn.a[i];
 		if (bwa_verbose >= 4) err_printf("* ---> Processing chain(%d) <---\n", i);
-		mem_chain2aln(opt, bns, pac, l_seq, (uint8_t*)seq, p, &regs);
+		mem_chain2aln(opt, bns, pac, l_seq, (uint8_t*)seq, p, &regs, buf);
 		free(chn.a[i].seeds);
 	}
 	free(chn.a);
@@ -1352,30 +1245,17 @@ mem_aln_t mem_reg2aln(const mem_opt_t *opt, const bntseq_t *bns, const uint8_t *
 	return a;
 }
 
-typedef struct {
-	const mem_opt_t *opt;
-	const bwt_t *bwt;
-	const FMTIndex *fmt;
-	const bntseq_t *bns;
-	const uint8_t *pac;
-	const mem_pestat_t *pes;
-	smem_aux_t **aux;
-	bseq1_t *seqs;
-	mem_alnreg_v *regs;
-	int64_t n_processed;
-} worker_t;
-
 static void worker1(void *data, int i, int tid)
 {
-	worker_t *w = (worker_t*)data;
+	mem_worker_t *w = (mem_worker_t*)data;
 	if (!(w->opt->flag&MEM_F_PE)) {
 		if (bwa_verbose >= 4) printf("=====> Processing read '%s' <=====\n", w->seqs[i].name);
-		w->regs[i] = mem_align1_core(w->opt, w->bwt, w->fmt, w->bns, w->pac, w->seqs[i].l_seq, w->seqs[i].seq, w->aux[tid]);
+		w->regs[i] = mem_align1_core(w->opt, w->fmt, w->bns, w->pac, w->seqs[i].l_seq, w->seqs[i].seq, w->aux[tid]);
 	} else {
 		if (bwa_verbose >= 4) printf("=====> Processing read '%s'/1 <=====\n", w->seqs[i<<1|0].name);
-		w->regs[i<<1|0] = mem_align1_core(w->opt, w->bwt, w->fmt, w->bns, w->pac, w->seqs[i<<1|0].l_seq, w->seqs[i<<1|0].seq, w->aux[tid]);
+		w->regs[i<<1|0] = mem_align1_core(w->opt, w->fmt, w->bns, w->pac, w->seqs[i<<1|0].l_seq, w->seqs[i<<1|0].seq, w->aux[tid]);
 		if (bwa_verbose >= 4) printf("=====> Processing read '%s'/2 <=====\n", w->seqs[i<<1|1].name);
-		w->regs[i<<1|1] = mem_align1_core(w->opt, w->bwt, w->fmt, w->bns, w->pac, w->seqs[i<<1|1].l_seq, w->seqs[i<<1|1].seq, w->aux[tid]);
+		w->regs[i<<1|1] = mem_align1_core(w->opt, w->fmt, w->bns, w->pac, w->seqs[i<<1|1].l_seq, w->seqs[i<<1|1].seq, w->aux[tid]);
 	}
 }
 
@@ -1383,7 +1263,7 @@ static void worker2(void *data, int i, int tid)
 {
 	extern int mem_sam_pe(const mem_opt_t *opt, const bntseq_t *bns, const uint8_t *pac, const mem_pestat_t pes[4], uint64_t id, bseq1_t s[2], mem_alnreg_v a[2]);
 	extern void mem_reg2ovlp(const mem_opt_t *opt, const bntseq_t *bns, const uint8_t *pac, bseq1_t *s, mem_alnreg_v *a);
-	worker_t *w = (worker_t*)data;
+	mem_worker_t *w = (mem_worker_t*)data;
 	if (!(w->opt->flag&MEM_F_PE)) {
 		if (bwa_verbose >= 4) printf("=====> Finalizing read '%s' <=====\n", w->seqs[i].name);
 		mem_mark_primary_se(w->opt, w->regs[i].n, w->regs[i].a, w->n_processed + i);
@@ -1397,33 +1277,73 @@ static void worker2(void *data, int i, int tid)
 	}
 }
 
-void mem_process_seqs(const mem_opt_t *opt, const bwt_t *bwt, const FMTIndex *fmt, const bntseq_t *bns, const uint8_t *pac, int64_t n_processed, int n, bseq1_t *seqs, const mem_pestat_t *pes0)
+static smem_aux_t *smem_aux_init()
+{
+	smem_aux_t *a;
+	a = calloc(1, sizeof(smem_aux_t));
+	a->tmpv[0] = calloc(1, sizeof(bwtintv_v));
+	a->tmpv[1] = calloc(1, sizeof(bwtintv_v));
+	a->sw_buf = calloc(1, sizeof(buf_t));
+	a->seq_buf = calloc(1, sizeof(buf_t));
+	return a;
+}
+
+static void smem_aux_destroy(smem_aux_t *a)
+{	
+	free(a->tmpv[0]->a); free(a->tmpv[0]);
+	free(a->tmpv[1]->a); free(a->tmpv[1]);
+	free(a->mem.a); free(a->mem1.a);
+	free(a);
+}
+
+// 初始化线程需要的数据
+mem_worker_t *init_mem_worker(const mem_opt_t *opt, const FMTIndex *fmt, const bntseq_t *bns, const uint8_t *pac)
+{
+	int i;
+	mem_worker_t *w = calloc(1, sizeof(mem_worker_t));
+	w->opt = opt; w->bns = bns; w->pac = pac; w->fmt = fmt;
+	w->aux = malloc(opt->n_threads * sizeof(smem_aux_t));
+	for (i = 0; i < opt->n_threads; ++i)
+		w->aux[i] = smem_aux_init();
+	return w;
+}
+
+void mem_process_seqs(const mem_opt_t *opt, mem_worker_t *w, int64_t n_processed, int n, bseq1_t *seqs, const mem_pestat_t *pes0)
 {
 	extern void kt_for(int n_threads, void (*func)(void*,int,int), void *data, int n);
-	worker_t w;
 	mem_pestat_t pes[4];
 	double ctime, rtime;
-	int i;
 
 	ctime = cputime(); rtime = realtime();
-	global_bns = bns;
-	w.regs = malloc(n * sizeof(mem_alnreg_v));
-	w.opt = opt; w.bwt = bwt; w.bns = bns; w.pac = pac;
-	w.seqs = seqs; w.n_processed = n_processed;
-	w.pes = &pes[0]; w.fmt = fmt;
-	w.aux = malloc(opt->n_threads * sizeof(smem_aux_t));
-	for (i = 0; i < opt->n_threads; ++i)
-		w.aux[i] = smem_aux_init();
-	kt_for(opt->n_threads, worker1, &w, (opt->flag&MEM_F_PE)? n>>1 : n); // find mapping positions
-	for (i = 0; i < opt->n_threads; ++i)
-		smem_aux_destroy(w.aux[i]);
-	free(w.aux);
+	global_bns = w->bns;
+
+	if (w->n < n) {
+		w->n = n;
+		w->regs = realloc(w->regs, n * sizeof(mem_alnreg_v));
+	}
+	w->seqs = seqs; w->n_processed = n_processed;
+	w->pes = &pes[0];
+
+#ifdef SHOW_PERF
+	int64_t tmp_time = realtime_msec();
+#endif
+	kt_for(opt->n_threads, worker1, w, (opt->flag&MEM_F_PE)? n>>1 : n); // find mapping positions
+#ifdef SHOW_PERF
+	tmp_time = realtime_msec() - tmp_time;
+	__sync_fetch_and_add(&time_work1, tmp_time);
+	tmp_time = realtime_msec();
+#endif
+
 	if (opt->flag&MEM_F_PE) { // infer insert sizes if not provided
 		if (pes0) memcpy(pes, pes0, 4 * sizeof(mem_pestat_t)); // if pes0 != NULL, set the insert-size distribution as pes0
-		else mem_pestat(opt, bns->l_pac, n, w.regs, pes); // otherwise, infer the insert size distribution from data
+		else mem_pestat(opt, w->bns->l_pac, n, w->regs, pes); // otherwise, infer the insert size distribution from data
 	}
-	kt_for(opt->n_threads, worker2, &w, (opt->flag&MEM_F_PE)? n>>1 : n); // generate alignment
-	free(w.regs);
+	kt_for(opt->n_threads, worker2, w, (opt->flag&MEM_F_PE)? n>>1 : n); // generate alignment
+#ifdef SHOW_PERF
+	tmp_time = realtime_msec() - tmp_time;
+	__sync_fetch_and_add(&time_work2, tmp_time);
+#endif
+	//free(w.regs);
 	if (bwa_verbose >= 3)
 		fprintf(stderr, "[M::%s] Processed %d reads in %.3f CPU sec, %.3f real sec\n", __func__, n, cputime() - ctime, realtime() - rtime);
 }
diff --git a/bwamem.h b/bwamem.h
index 6f92c5e..4a615c0 100644
--- a/bwamem.h
+++ b/bwamem.h
@@ -31,6 +31,7 @@
 #include "bntseq.h"
 #include "bwa.h"
 #include "fmt_idx.h"
+#include "utils.h"
 
 #define MEM_MAPQ_COEF 30.0
 #define MEM_MAPQ_MAX  60
@@ -124,9 +125,46 @@ typedef struct { // This struct is only used for the convenience of API.
 	int score, sub, alt_sc;
 } mem_aln_t;
 
+typedef struct {
+	int64_t rbeg;
+	int32_t qbeg, len;
+	int score;
+} mem_seed_t; // unaligned memory
+
+typedef struct {
+	int n, m, first, rid;
+	uint32_t w:29, kept:2, is_alt:1;
+	float frac_rep;
+	int64_t pos;
+	mem_seed_t *seeds;
+} mem_chain_t;
+
+typedef struct { size_t n, m; mem_chain_t *a;  } mem_chain_v;
+
+typedef struct {
+	bwtintv_v mem, mem1, *tmpv[2];
+	buf_t *sw_buf, *seq_buf;
+} smem_aux_t;
+
+typedef struct {
+	const mem_opt_t *opt;
+	const bwt_t *bwt;
+	const FMTIndex *fmt;
+	const bntseq_t *bns;
+	const uint8_t *pac;
+	const mem_pestat_t *pes;
+	smem_aux_t **aux;
+	bseq1_t *seqs;
+	mem_alnreg_v *regs;
+	int64_t n_processed;
+	int64_t n;
+} mem_worker_t;
+
+
 #ifdef __cplusplus
 extern "C" {
 #endif
+	mem_worker_t *init_mem_worker(const mem_opt_t *opt, const FMTIndex *fmt, const bntseq_t *bns, const uint8_t *pac);
 
 	smem_i *smem_itr_init(const bwt_t *bwt);
 	void smem_itr_destroy(smem_i *itr);
@@ -159,7 +197,7 @@ extern "C" {
 	 * @param pes0   insert-size info; if NULL, infer from data; if not NULL, it should be an array with 4 elements,
 	 *               corresponding to each FF, FR, RF and RR orientation. See mem_pestat() for more info.
 	 */
-	void mem_process_seqs(const mem_opt_t *opt, const bwt_t *bwt, const FMTIndex *fmt, const bntseq_t *bns, const uint8_t *pac, int64_t n_processed, int n, bseq1_t *seqs, const mem_pestat_t *pes0);
+	void mem_process_seqs(const mem_opt_t *opt, mem_worker_t *w, int64_t n_processed, int n, bseq1_t *seqs, const mem_pestat_t *pes0);
 
 	/**
 	 * Find the aligned regions for one query sequence
diff --git a/bwamem_pair.c b/bwamem_pair.c
index ef79521..bba5c2b 100644
--- a/bwamem_pair.c
+++ b/bwamem_pair.c
@@ -377,12 +377,12 @@ int mem_sam_pe(const mem_opt_t *opt, const bntseq_t *bns, const uint8_t *pac, co
 				aa[i][n_aa[i]++] = g[i];
 			}
 		}
+		s[0].sam.l = 0;
 		for (i = 0; i < n_aa[0]; ++i)
-			mem_aln2sam(opt, bns, &str, &s[0], n_aa[0], aa[0], i, &h[1]); // write read1 hits
-		s[0].sam = strdup(str.s); str.l = 0;
+			mem_aln2sam(opt, bns, &s[0].sam, &s[0], n_aa[0], aa[0], i, &h[1]); // write read1 hits
+		s[1].sam.l = 0;
 		for (i = 0; i < n_aa[1]; ++i)
-			mem_aln2sam(opt, bns, &str, &s[1], n_aa[1], aa[1], i, &h[0]); // write read2 hits
-		s[1].sam = str.s;
+			mem_aln2sam(opt, bns, &s[1].sam, &s[1], n_aa[1], aa[1], i, &h[0]); // write read2 hits
 		if (strcmp(s[0].name, s[1].name) != 0) err_fatal(__func__, "paired reads have different names: \"%s\", \"%s\"\n", s[0].name, s[1].name);
 		// free
 		for (i = 0; i < 2; ++i) {
diff --git a/bwtsw2_aux.c b/bwtsw2_aux.c
index d225187..5a996d4 100644
--- a/bwtsw2_aux.c
+++ b/bwtsw2_aux.c
@@ -130,7 +130,7 @@ void bsw2_extend_left(const bsw2opt_t *opt, bwtsw2_t *b, uint8_t *_query, int lq
 		for (k = p->k - 1, j = 0; k > 0 && j < lt; --k) // FIXME: k=0 not considered!
 			target[j++] = pac[k>>2] >> (~k&3)*2 & 0x3;
 		lt = j;
-		score = ksw_extend(p->beg, &query[lq - p->beg], lt, target, 5, mat, opt->q, opt->r, opt->bw, 0, -1, p->G, &qle, &tle, 0, 0, 0);
+		score = ksw_extend(p->beg, &query[lq - p->beg], lt, target, 5, mat, opt->q, opt->r, opt->bw, 0, -1, p->G, &qle, &tle, 0, 0, 0, 0);
 		if (score > p->G) { // extensible
 			p->G = score;
 			p->k -= tle;
@@ -158,7 +158,7 @@ void bsw2_extend_rght(const bsw2opt_t *opt, bwtsw2_t *b, uint8_t *query, int lq,
 		for (k = p->k, j = 0; k < p->k + lt && k < l_pac; ++k)
 			target[j++] = pac[k>>2] >> (~k&3)*2 & 0x3;
 		lt = j;
-		score = ksw_extend(lq - p->beg, &query[p->beg], lt, target, 5, mat, opt->q, opt->r, opt->bw, 0, -1, 1, &qle, &tle, 0, 0, 0) - 1;
+		score = ksw_extend(lq - p->beg, &query[p->beg], lt, target, 5, mat, opt->q, opt->r, opt->bw, 0, -1, 1, &qle, &tle, 0, 0, 0, 0) - 1;
 //		if (score < p->G) fprintf(stderr, "[bsw2_extend_hits] %d < %d\n", score, p->G);
 		if (score >= p->G) {
 			p->G = score;
@@ -728,10 +728,11 @@ void bsw2_aln(const bsw2opt_t *opt, const bntseq_t *bns, bwt_t * const target, c
 {
 	gzFile fp, fp2;
 	kseq_t *ks, *ks2;
-	int l, is_pe = 0, i, n;
+	int l, is_pe = 0, i, n, m = 0;
+	int64_t seq_size = 0;
 	uint8_t *pac;
 	bsw2seq_t *_seq;
-	bseq1_t *bseq;
+	bseq1_t *bseq = 0;
 
 	pac = calloc(bns->l_pac/4+1, 1);
 	for (l = 0; l < bns->n_seqs; ++l)
@@ -745,7 +746,8 @@ void bsw2_aln(const bsw2opt_t *opt, const bntseq_t *bns, bwt_t * const target, c
 		ks2 = kseq_init(fp2);
 		is_pe = 1;
 	} else fp2 = 0, ks2 = 0, is_pe = 0;
-	while ((bseq = bseq_read(opt->chunk_size * opt->n_threads, &n, ks, ks2)) != 0) {
+	bseq_read(opt->chunk_size * opt->n_threads, &n, ks, ks2, 1, &seq_size, &m, &bseq);
+	while (n > 0) {
 		int size = 0;
 		if (n > _seq->max) {
 			_seq->max = n;
@@ -761,10 +763,11 @@ void bsw2_aln(const bsw2opt_t *opt, const bntseq_t *bns, bwt_t * const target, c
 			size += p->l;
 		}
 		fprintf(stderr, "[bsw2_aln] read %d sequences/pairs (%d bp) ...\n", n, size);
-		free(bseq);
 		process_seqs(_seq, opt, bns, pac, target, is_pe);
+		bseq_read(opt->chunk_size * opt->n_threads, &n, ks, ks2, 1, &seq_size, &m, &bseq);
 	}
 	// free
+	if (bseq) free(bseq);
 	free(pac);
 	free(_seq->seq); free(_seq);
 	kseq_destroy(ks);
diff --git a/fastmap.c b/fastmap.c
index 6a3aa35..ea0ca56 100644
--- a/fastmap.c
+++ b/fastmap.c
@@ -56,7 +56,10 @@ int64_t time_ksw_extend2 = 0,
 		time_bwt_occ4 = 0,
 		time_bwt_sa = 0,
 		time_bwt_sa_read = 0,
-		time_bns = 0;
+		time_bns = 0,
+		time_work1 = 0,
+		time_work2 = 0,
+		time_flt_chain = 0;
 
 int64_t dn = 0, n16 = 0, n17 = 0, n18 = 0, n19 = 0, nall = 0, num_sa = 0;
 int64_t s1n = 0, s2n = 0, s3n = 0, s1l = 0, s2l = 0, s3l = 0;
@@ -71,6 +74,12 @@ void *kopen(const char *fn, int *_fd);
 int kclose(void *a);
 void kt_pipeline(int n_threads, void *(*func)(void*, int, void*), void *shared_data, int n_steps);
 
+typedef struct {
+	int n_seqs;
+	int m_seqs;
+	bseq1_t *seqs;
+} ktp_data_t;
+
 typedef struct {
 	kseq_t *ks, *ks2;
 	mem_opt_t *opt;
@@ -78,40 +87,30 @@ typedef struct {
 	int64_t n_processed;
 	int copy_comment, actual_chunk_size;
 	bwaidx_t *idx;
+	mem_worker_t *w;
+	int data_idx; // pingpong buffer index
+	ktp_data_t *data;
 } ktp_aux_t;
 
-typedef struct {
-	ktp_aux_t *aux;
-	int n_seqs;
-	bseq1_t *seqs;
-} ktp_data_t;
-
 static void *process(void *shared, int step, void *_data)
 {
 	ktp_aux_t *aux = (ktp_aux_t*)shared;
 	ktp_data_t *data = (ktp_data_t*)_data;
 	int i;
 	if (step == 0) {
-		ktp_data_t *ret;
+		ktp_data_t *ret = aux->data + aux->data_idx;
+		aux->data_idx = !aux->data_idx;
 		int64_t size = 0;
-		ret = calloc(1, sizeof(ktp_data_t));
-		ret->seqs = bseq_read(aux->actual_chunk_size, &ret->n_seqs, aux->ks, aux->ks2);
-		if (ret->seqs == 0) {
-			free(ret);
+		bseq_read(aux->actual_chunk_size, &ret->n_seqs, aux->ks, aux->ks2, aux->copy_comment, &size, &ret->m_seqs, &ret->seqs);
+		if (ret->n_seqs == 0) {
 			return 0;
 		}
-		if (!aux->copy_comment)
-			for (i = 0; i < ret->n_seqs; ++i) {
-				free(ret->seqs[i].comment);
-				ret->seqs[i].comment = 0;
-			}
-		for (i = 0; i < ret->n_seqs; ++i) size += ret->seqs[i].l_seq;
 		if (bwa_verbose >= 3)
 			fprintf(stderr, "[M::%s] read %d sequences (%ld bp)...\n", __func__, ret->n_seqs, (long)size);
 		return ret;
 	} else if (step == 1) {
 		const mem_opt_t *opt = aux->opt;
-		const bwaidx_t *idx = aux->idx;
+		// const bwaidx_t *idx = aux->idx;
 		if (opt->flag & MEM_F_SMARTPE) {
 			bseq1_t *sep[2];
 			int n_sep[2];
@@ -121,28 +120,25 @@ static void *process(void *shared, int step, void *_data)
 				fprintf(stderr, "[M::%s] %d single-end sequences; %d paired-end sequences\n", __func__, n_sep[0], n_sep[1]);
 			if (n_sep[0]) {
 				tmp_opt.flag &= ~MEM_F_PE;
-				mem_process_seqs(&tmp_opt, idx->bwt, idx->fmt, idx->bns, idx->pac, aux->n_processed, n_sep[0], sep[0], 0);
+				mem_process_seqs(&tmp_opt, aux->w, aux->n_processed, n_sep[0], sep[0], 0);
 				for (i = 0; i < n_sep[0]; ++i)
 					data->seqs[sep[0][i].id].sam = sep[0][i].sam;
 			}
 			if (n_sep[1]) {
 				tmp_opt.flag |= MEM_F_PE;
-				mem_process_seqs(&tmp_opt, idx->bwt, idx->fmt, idx->bns, idx->pac, aux->n_processed + n_sep[0], n_sep[1], sep[1], aux->pes0);
+				mem_process_seqs(&tmp_opt, aux->w, aux->n_processed + n_sep[0], n_sep[1], sep[1], aux->pes0);
 				for (i = 0; i < n_sep[1]; ++i)
 					data->seqs[sep[1][i].id].sam = sep[1][i].sam;
 			}
 			free(sep[0]); free(sep[1]);
 		} else
-			mem_process_seqs(opt, idx->bwt, idx->fmt, idx->bns, idx->pac, aux->n_processed, data->n_seqs, data->seqs, aux->pes0);
+			mem_process_seqs(opt, aux->w, aux->n_processed, data->n_seqs, data->seqs, aux->pes0);
 		aux->n_processed += data->n_seqs;
 		return data;
 	} else if (step == 2) {
 		for (i = 0; i < data->n_seqs; ++i) {
-			if (data->seqs[i].sam) err_fputs(data->seqs[i].sam, stdout);
-			free(data->seqs[i].name); free(data->seqs[i].comment);
-			free(data->seqs[i].seq); free(data->seqs[i].qual); free(data->seqs[i].sam);
+			if (data->seqs[i].sam.l) err_fputs(data->seqs[i].sam.s, stdout);
 		}
-		free(data->seqs); free(data);
 		return 0;
 	}
 	return 0;
@@ -166,8 +162,9 @@ static void update_a(mem_opt_t *opt, const mem_opt_t *opt0)
 
 int main_mem(int argc, char *argv[])
 {
+#ifdef SHOW_PERF
 	fp1 = fopen("./test_out.txt", "w");
-
+#endif
 	mem_opt_t *opt, opt0;
 	int fd, fd2, i, c, ignore_alt = 0, no_mt_io = 0;
 	int fixed_chunk_size = -1;
@@ -418,6 +415,8 @@ int main_mem(int argc, char *argv[])
 		}
 	}
 	
+	aux.w = init_mem_worker(opt, aux.idx->fmt, aux.idx->bns, aux.idx->pac);
+	aux.data = calloc(2, sizeof(ktp_data_t));
 
 	bwa_print_sam_hdr(aux.idx->bns, hdr_line);
 	aux.actual_chunk_size = fixed_chunk_size > 0? fixed_chunk_size : opt->chunk_size * opt->n_threads;
@@ -434,20 +433,14 @@ int main_mem(int argc, char *argv[])
 
 #ifdef SHOW_PERF
 	fprintf(stderr, "\n");
+	fprintf(stderr, "time_work1: %f s\n", time_work1 / 1000.0 / 1);
+	fprintf(stderr, "time_work2: %f s\n", time_work2 / 1000.0 / 1);
+	fprintf(stderr, "time_flt_chain: %f s\n", time_flt_chain / 1000.0 / opt->n_threads);
 	fprintf(stderr, "time_seed_1: %f s\n", time_seed_1 / 1000.0 / opt->n_threads);
 	fprintf(stderr, "time_seed_2: %f s\n", time_seed_2 / 1000.0 / opt->n_threads);
 	fprintf(stderr, "time_seed_3: %f s\n", time_seed_3 / 1000.0 / opt->n_threads);
 	fprintf(stderr, "time_bwt_sa: %f s\n", time_bwt_sa / 1000.0 / opt->n_threads);
 	fprintf(stderr, "time_ksw_extend2: %f s\n", time_ksw_extend2 / 1000.0 / opt->n_threads);
-	fprintf(stderr, "time_bns: %f s\n", time_bns / 1000.0 / opt->n_threads);
-	fprintf(stderr, "s1 num: %ld\n", s1n);
-	fprintf(stderr, "s2 num: %ld\n", s2n);
-	fprintf(stderr, "s3 num: %ld\n", s3n);
-	fprintf(stderr, "s1 len: %ld\n", s1l / s1n);
-	fprintf(stderr, "s2 len: %ld\n", s2l / s2n);
-	fprintf(stderr, "s3 len: %ld\n", s3l / s3n);
-	fprintf(stderr, "get sa num: %ld\n", num_sa);
-	fprintf(stderr, "seed 2 num: %ld\n", g_num_smem2);
 	fprintf(stderr, "\n");
 
 	fclose(fp1);
diff --git a/fmt_idx.c b/fmt_idx.c
index 95578b4..c7b3f4e 100644
--- a/fmt_idx.c
+++ b/fmt_idx.c
@@ -565,19 +565,19 @@ int fmt_smem(const FMTIndex *fmt, int len, const uint8_t *q, int x, int min_intv
         if (q[i] < 4 && q[i + 1] < 4)
         {
             fmt_extend2(fmt, &ik, &ok1, &ok2, 0, 3 - q[i], 3 - q[i + 1]);
-//            __builtin_prefetch(fmt_occ_intv(fmt, ok2.x[1] - 1), 0, 2);
-//            __builtin_prefetch(fmt_occ_intv(fmt, ok2.x[1] - 1 + ok2.x[2]), 0, 2);
+            __builtin_prefetch(fmt_occ_intv(fmt, ok2.x[1] - 1), 0, 2);
+            __builtin_prefetch(fmt_occ_intv(fmt, ok2.x[1] - 1 + ok2.x[2]), 0, 2);
             CHECK_INTV_CHANGE(ik, ok1, i + 1);
             CHECK_INTV_CHANGE(ik, ok2, i + 2);
             // 在这里进行判断是否只有一个候选了
-            //if (min_intv == 1 && ok2.x[2] == min_intv)
-            //{
-            //    direct_extend(fmt, len, q, x, i + 2, ok2.x[0], &mt);
-            //    kv_push(bwtintv_t, *mem, mt);
-            //    ret = (uint32_t)mt.info;
-            //    if (only_forward || mt.rm[0].qs == 0 || q[mt.rm[0].qs - 1] > 3) goto fmt_smem_end;
-            //    goto backward_search;
-            //}
+            if (min_intv == 1 && ok2.x[2] == min_intv)
+            {
+                direct_extend(fmt, len, q, x, i + 2, ok2.x[0], &mt);
+                kv_push(bwtintv_t, *mem, mt);
+                ret = (uint32_t)mt.info;
+                if (only_forward || mt.rm[0].qs == 0 || q[mt.rm[0].qs - 1] > 3) goto fmt_smem_end;
+                goto backward_search;
+            }
         } else if (q[i] < 4) // q[i+1] >= 4
         {
             fmt_extend1(fmt, &ik, &ok1, 0, 3 - q[i]);
@@ -639,8 +639,8 @@ backward_search:
             if (q[i] < 4 && q[i - 1] < 4) // 两个都可以扩展
             {
                 fmt_extend2(fmt, p, &ok1, &ok2, 1, q[i], q[i - 1]);
-//                __builtin_prefetch(fmt_occ_intv(fmt, ok2.x[0] - 1), 0, 2);
-//                __builtin_prefetch(fmt_occ_intv(fmt, ok2.x[0] - 1 + ok2.x[2]), 0, 2);
+                __builtin_prefetch(fmt_occ_intv(fmt, ok2.x[0] - 1), 0, 2);
+                __builtin_prefetch(fmt_occ_intv(fmt, ok2.x[0] - 1 + ok2.x[2]), 0, 2);
                 CHECK_INTV_ADD_MEM(ok1, i + 1, *p, mem);
                 ok1.info = p->info;
                 CHECK_INTV_ADD_MEM(ok2, i, ok1, mem);
@@ -694,9 +694,6 @@ int fmt_seed_strategy1(const FMTIndex *fmt, int len, const uint8_t *q, int x, in
     bwt_kmer_get(&fmt->kmer_hash, &ik, qbit, kmer_len-1); // 初始碱基位置
     ik.info = x + kmer_len;
 
-    //fmt_set_intv(fmt, q[x], ik);
-    //ik.info = x + 1;
-
 //    __builtin_prefetch(fmt_occ_intv(fmt, ik.x[1] - 1), 0, 2);
 //    __builtin_prefetch(fmt_occ_intv(fmt, ik.x[1] - 1 + ik.x[2]), 0, 2);
 
@@ -713,8 +710,8 @@ int fmt_seed_strategy1(const FMTIndex *fmt, int len, const uint8_t *q, int x, in
         if (q[i] < 4 && q[i + 1] < 4)
         {
             fmt_extend2(fmt, &ik, &ok1, &ok2, 0, 3 - q[i], 3 - q[i + 1]);
-//            __builtin_prefetch(fmt_occ_intv(fmt, ok2.x[1] - 1), 0, 2);
-//            __builtin_prefetch(fmt_occ_intv(fmt, ok2.x[1] - 1 + ok2.x[2]), 0, 2);
+            __builtin_prefetch(fmt_occ_intv(fmt, ok2.x[1] - 1), 0, 2);
+            __builtin_prefetch(fmt_occ_intv(fmt, ok2.x[1] - 1 + ok2.x[2]), 0, 2);
             COND_SET_RETURN(ok1, *mem, x, i, max_intv, min_len);
             COND_SET_RETURN(ok2, *mem, x, i + 1, max_intv, min_len);
             ik = ok2;
diff --git a/fmt_idx.h b/fmt_idx.h
index bc55b74..3b3c628 100644
--- a/fmt_idx.h
+++ b/fmt_idx.h
@@ -32,9 +32,11 @@ Date : 2023/12/24
 #elif FMT_MID_INTERVAL == 16
 #define fmt_occ_intv(b, k) ((b)->bwt + (k) / FMT_OCC_INTERVAL * (FMT_OCC_INTERVAL / 8 + 80))
 #elif FMT_MID_INTERVAL == 32
-#define fmt_occ_intv(b, k) ((b)->bwt + (k) / FMT_OCC_INTERVAL * (FMT_OCC_INTERVAL / 8 + 48))
+//#define fmt_occ_intv(b, k) ((b)->bwt + (k) / FMT_OCC_INTERVAL * (FMT_OCC_INTERVAL / 8 + 48))
+#define fmt_occ_intv(b, k) ((b)->bwt + ((k) >> 8) * 80)
 #elif FMT_MID_INTERVAL == 64
-#define fmt_occ_intv(b, k) ((b)->bwt + (k) / FMT_OCC_INTERVAL * (FMT_OCC_INTERVAL / 8 + 32))
+//#define fmt_occ_intv(b, k) ((b)->bwt + (k) / FMT_OCC_INTERVAL * (FMT_OCC_INTERVAL / 8 + 32))
+#define fmt_occ_intv(b, k) ((b)->bwt + ((k) >> 8 << 6))
 #elif FMT_MID_INTERVAL == 128
 #define fmt_occ_intv(b, k) ((b)->bwt + (k) / FMT_OCC_INTERVAL * (FMT_OCC_INTERVAL / 8 + 24))
 #else
diff --git a/ksw.c b/ksw.c
index 1e584e9..21fb7e8 100644
--- a/ksw.c
+++ b/ksw.c
@@ -413,15 +413,24 @@ typedef struct {
 	int32_t h, e;
 } eh_t;
 
-int ksw_extend2(int qlen, const uint8_t *query, int tlen, const uint8_t *target, int m, const int8_t *mat, int o_del, int e_del, int o_ins, int e_ins, int w, int end_bonus, int zdrop, int h0, int *_qle, int *_tle, int *_gtle, int *_gscore, int *_max_off)
+int ksw_extend2(int qlen, const uint8_t *query, int tlen, const uint8_t *target, int m, const int8_t *mat, int o_del, int e_del, int o_ins, int e_ins, int w, int end_bonus, int zdrop, int h0, int *_qle, int *_tle, int *_gtle, int *_gscore, int *_max_off, buf_t *buf)
 {
 	eh_t *eh; // score array
 	int8_t *qp; // query profile
 	int i, j, k, oe_del = o_del + e_del, oe_ins = o_ins + e_ins, beg, end, max, max_i, max_j, max_ins, max_del, max_ie, gscore, max_off;
+	int mem_size = qlen * m + (qlen + 1) * 8;
 	assert(h0 > 0);
 	// allocate memory
-	qp = malloc(qlen * m);
-	eh = calloc(qlen + 1, 8);
+	if (mem_size > buf->m) {
+		buf->m = mem_size;
+		buf->addr = realloc(buf->addr, mem_size);
+	}
+	//qp = malloc(qlen * m);
+	//eh = calloc(qlen + 1, 8);
+	qp = (int8_t*)buf->addr;
+	eh = (eh_t*)(buf->addr + qlen * m);
+	memset(eh, 0, (qlen + 1) * 8);
+
 	// generate the query profile
 	for (k = i = 0; k < m; ++k) {
 		const int8_t *p = &mat[k * m];
@@ -505,7 +514,7 @@ int ksw_extend2(int qlen, const uint8_t *query, int tlen, const uint8_t *target,
 		end = j + 2 < qlen? j + 2 : qlen;
 		//beg = 0; end = qlen; // uncomment this line for debugging
 	}
-	free(eh); free(qp);
+	// free(eh); free(qp);
 	if (_qle) *_qle = max_j + 1;
 	if (_tle) *_tle = max_i + 1;
 	if (_gtle) *_gtle = max_ie + 1;
@@ -514,9 +523,12 @@ int ksw_extend2(int qlen, const uint8_t *query, int tlen, const uint8_t *target,
 	return max;
 }
 
-int ksw_extend(int qlen, const uint8_t *query, int tlen, const uint8_t *target, int m, const int8_t *mat, int gapo, int gape, int w, int end_bonus, int zdrop, int h0, int *qle, int *tle, int *gtle, int *gscore, int *max_off)
+int ksw_extend(int qlen, const uint8_t *query, int tlen, const uint8_t *target, int m, const int8_t *mat, int gapo, int gape, int w, int end_bonus, int zdrop, int h0, int *qle, int *tle, int *gtle, int *gscore, int *max_off, buf_t *buf)
 {
-	return ksw_extend2(qlen, query, tlen, target, m, mat, gapo, gape, gapo, gape, w, end_bonus, zdrop, h0, qle, tle, gtle, gscore, max_off);
+	if (buf == 0) buf = calloc(1, sizeof(buf_t));
+	return ksw_extend2(qlen, query, tlen, target, m, mat, gapo, gape, gapo, gape, w, end_bonus, zdrop, h0, qle, tle, gtle, gscore, max_off, buf);
+	free(buf->addr);
+	free(buf);
 }
 
 /********************
diff --git a/ksw.h b/ksw.h
index 5d45a67..c14caa8 100644
--- a/ksw.h
+++ b/ksw.h
@@ -2,6 +2,7 @@
 #define __AC_KSW_H
 
 #include <stdint.h>
+#include "utils.h"
 
 #define KSW_XBYTE  0x10000
 #define KSW_XSTOP  0x20000
@@ -104,8 +105,10 @@ extern "C" {
 	 *
 	 * @return        best semi-local alignment score
 	 */
-	int ksw_extend(int qlen, const uint8_t *query, int tlen, const uint8_t *target, int m, const int8_t *mat, int gapo, int gape, int w, int end_bonus, int zdrop, int h0, int *qle, int *tle, int *gtle, int *gscore, int *max_off);
-	int ksw_extend2(int qlen, const uint8_t *query, int tlen, const uint8_t *target, int m, const int8_t *mat, int o_del, int e_del, int o_ins, int e_ins, int w, int end_bonus, int zdrop, int h0, int *qle, int *tle, int *gtle, int *gscore, int *max_off);
+	int ksw_extend(int qlen, const uint8_t *query, int tlen, const uint8_t *target, int m, const int8_t *mat, int gapo, int gape, int w, int end_bonus, int zdrop, int h0, int *qle, int *tle, int *gtle, int *gscore, int *max_off, buf_t *buf);
+	int ksw_extend2(int qlen, const uint8_t *query, int tlen, const uint8_t *target, int m, const int8_t *mat, int o_del, int e_del, int o_ins, int e_ins, int w, int end_bonus, int zdrop, int h0, int *qle, int *tle, int *gtle, int *gscore, int *max_off, buf_t *buf);
+	int ksw_extend2_avx2(int qlen, const uint8_t *query, int tlen, const uint8_t *target, int is_left, int m, const int8_t *mat, int o_del, int e_del,
+						 int o_ins, int e_ins, int a, int b, int w, int end_bonus, int zdrop, int h0, int *_qle, int *_tle, int *_gtle, int *_gscore, int *_max_off, buf_t *buf);
 
 #ifdef __cplusplus
 }
diff --git a/ksw_extend2_avx2.c b/ksw_extend2_avx2.c
new file mode 100644
index 0000000..dc4a8f1
--- /dev/null
+++ b/ksw_extend2_avx2.c
@@ -0,0 +1,504 @@
+#include <stdlib.h>
+#include <stdint.h>
+#include <assert.h>
+#include <emmintrin.h>
+#include <stdio.h>
+#include <immintrin.h>
+#include <emmintrin.h>
+
+#ifdef __GNUC__
+#define LIKELY(x) __builtin_expect((x),1)
+#define UNLIKELY(x) __builtin_expect((x),0)
+#else
+#define LIKELY(x) (x)
+#define UNLIKELY(x) (x)
+#endif
+
+#undef MAX
+#undef MIN
+#define MAX(x, y) ((x) > (y) ? (x) : (y))
+#define MIN(x, y) ((x) < (y) ? (x) : (y))
+#define SIMD_WIDTH 16
+
+typedef struct { size_t m; uint8_t *addr; } buf_t;
+
+extern int ksw_extend2_avx2_u8(int qlen, const uint8_t *query,  int tlen, const uint8_t *target, int is_left, int m,  const int8_t *mat,  int o_del,  int e_del,
+		int o_ins, int e_ins, int a, int b, int w, int end_bonus, int zdrop, int h0, int *_qle, int *_tle, int *_gtle, int *_gscore, int *_max_off, buf_t *buf);
+
+int ksw_extend2_origin(int qlen, const uint8_t *query,  int tlen, const uint8_t *target, int is_left, int m,  const int8_t *mat,  int o_del,  int e_del,
+		int o_ins, int e_ins, int w, int end_bonus, int zdrop, int h0, int *_qle, int *_tle, int *_gtle, int *_gscore, int *_max_off);
+
+
+static const uint16_t h_vec_int_mask[SIMD_WIDTH][SIMD_WIDTH] = {
+	{0xffff, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0},
+	{0xffff, 0xffff, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0},
+	{0xffff, 0xffff, 0xffff, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0},
+	{0xffff, 0xffff, 0xffff, 0xffff, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0},
+	{0xffff, 0xffff, 0xffff, 0xffff, 0xffff, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0},
+	{0xffff, 0xffff, 0xffff, 0xffff, 0xffff, 0xffff, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0},
+	{0xffff, 0xffff, 0xffff, 0xffff, 0xffff, 0xffff, 0xffff, 0, 0, 0, 0, 0, 0, 0, 0, 0},
+	{0xffff, 0xffff, 0xffff, 0xffff, 0xffff, 0xffff, 0xffff, 0xffff, 0, 0, 0, 0, 0, 0, 0, 0},
+	{0xffff, 0xffff, 0xffff, 0xffff, 0xffff, 0xffff, 0xffff, 0xffff, 0xffff, 0, 0, 0, 0, 0, 0, 0},
+	{0xffff, 0xffff, 0xffff, 0xffff, 0xffff, 0xffff, 0xffff, 0xffff, 0xffff, 0xffff, 0, 0, 0, 0, 0, 0},
+	{0xffff, 0xffff, 0xffff, 0xffff, 0xffff, 0xffff, 0xffff, 0xffff, 0xffff, 0xffff, 0xffff, 0, 0, 0, 0, 0},
+	{0xffff, 0xffff, 0xffff, 0xffff, 0xffff, 0xffff, 0xffff, 0xffff, 0xffff, 0xffff, 0xffff, 0xffff, 0, 0, 0, 0},
+	{0xffff, 0xffff, 0xffff, 0xffff, 0xffff, 0xffff, 0xffff, 0xffff, 0xffff, 0xffff, 0xffff, 0xffff, 0xffff, 0, 0, 0},
+	{0xffff, 0xffff, 0xffff, 0xffff, 0xffff, 0xffff, 0xffff, 0xffff, 0xffff, 0xffff, 0xffff, 0xffff, 0xffff, 0xffff, 0, 0},
+	{0xffff, 0xffff, 0xffff, 0xffff, 0xffff, 0xffff, 0xffff, 0xffff, 0xffff, 0xffff, 0xffff, 0xffff, 0xffff, 0xffff, 0xffff, 0},
+	{0xffff, 0xffff, 0xffff, 0xffff, 0xffff, 0xffff, 0xffff, 0xffff, 0xffff, 0xffff, 0xffff, 0xffff, 0xffff, 0xffff, 0xffff, 0xffff}
+};
+
+#define permute_mask _MM_SHUFFLE(0, 1, 2, 3)
+
+// 初始化变量
+#define SIMD_INIT \
+	int oe_del = o_del + e_del, oe_ins = o_ins + e_ins; \
+	__m256i zero_vec; \
+	__m256i max_vec; \
+	__m256i oe_del_vec; \
+	__m256i oe_ins_vec; \
+	__m256i e_del_vec; \
+	__m256i e_ins_vec; \
+	__m256i h_vec_mask[SIMD_WIDTH]; \
+	zero_vec = _mm256_setzero_si256(); \
+	oe_del_vec = _mm256_set1_epi16(-oe_del); \
+	oe_ins_vec = _mm256_set1_epi16(-oe_ins); \
+	e_del_vec = _mm256_set1_epi16(-e_del); \
+	e_ins_vec = _mm256_set1_epi16(-e_ins); \
+	__m256i match_sc_vec = _mm256_set1_epi16(a); \
+	__m256i mis_sc_vec = _mm256_set1_epi16(-b); \
+	__m256i amb_sc_vec = _mm256_set1_epi16(-1); \
+	__m256i amb_vec = _mm256_set1_epi16(4); \
+	for (i=0; i<SIMD_WIDTH; ++i) h_vec_mask[i] =  _mm256_loadu_si256((__m256i*) (&h_vec_int_mask[i]));
+
+/*
+ * e 表示当前ref的碱基被删除
+ * f 表示当前seq的碱基插入
+ * m 表示当前碱基匹配（可以相等，也可以不想等）
+ * h 表示最大值
+ */
+// load向量化数据
+#define SIMD_LOAD \
+	__m256i m1 = _mm256_loadu_si256((__m256i*) (&mA1[j])); \
+	__m256i e1 = _mm256_loadu_si256((__m256i*) (&eA1[j])); \
+	__m256i m1j1 = _mm256_loadu_si256((__m256i*) (&mA1[j-1])); \
+	__m256i f1j1 = _mm256_loadu_si256((__m256i*) (&fA1[j-1])); \
+	__m256i h0j1 = _mm256_loadu_si256((__m256i*) (&hA0[j-1])); \
+	__m256i qs_vec = _mm256_loadu_si256((__m256i*) (&seq[j-1])); \
+	__m256i ts_vec = _mm256_loadu_si256((__m256i*) (&ref[i]));
+
+// 比对ref和seq的序列，计算罚分
+#define SIMD_CMP_SEQ \
+	ts_vec = _mm256_permute4x64_epi64(ts_vec, permute_mask); \
+	ts_vec = _mm256_shufflelo_epi16(ts_vec, permute_mask); \
+	ts_vec = _mm256_shufflehi_epi16(ts_vec, permute_mask); \
+	__m256i match_mask_vec = _mm256_cmpeq_epi16(qs_vec, ts_vec); \
+	__m256i mis_score_vec  = _mm256_andnot_si256(match_mask_vec, mis_sc_vec); \
+	__m256i score_vec      = _mm256_and_si256(match_sc_vec, match_mask_vec); \
+	score_vec = _mm256_or_si256(score_vec, mis_score_vec); \
+	__m256i q_amb_mask_vec = _mm256_cmpeq_epi16(qs_vec, amb_vec); \
+	__m256i t_amb_mask_vec = _mm256_cmpeq_epi16(ts_vec, amb_vec); \
+	__m256i amb_mask_vec   = _mm256_or_si256(q_amb_mask_vec, t_amb_mask_vec); \
+	score_vec = _mm256_andnot_si256(amb_mask_vec, score_vec); \
+	__m256i amb_score_vec  = _mm256_and_si256(amb_mask_vec, amb_sc_vec); \
+	score_vec = _mm256_or_si256(score_vec, amb_score_vec);
+
+// 向量化计算h, e, f, m
+#define SIMD_COMPUTE \
+	__m256i en_vec0 = _mm256_add_epi16(m1, oe_del_vec); \
+	__m256i en_vec1 = _mm256_add_epi16(e1, e_del_vec); \
+	__m256i en_vec  = _mm256_max_epi16(en_vec0, en_vec1); \
+	__m256i fn_vec0 = _mm256_add_epi16(m1j1, oe_ins_vec); \
+	__m256i fn_vec1 = _mm256_add_epi16(f1j1, e_ins_vec); \
+	__m256i fn_vec  = _mm256_max_epi16(fn_vec0, fn_vec1); \
+	__m256i mn_vec0 = _mm256_add_epi16(h0j1, score_vec); \
+	__m256i mn_mask = _mm256_cmpgt_epi16(h0j1, zero_vec); \
+	__m256i mn_vec  = _mm256_and_si256(mn_vec0, mn_mask); \
+	__m256i hn_vec0 = _mm256_max_epi16(en_vec, fn_vec); \
+	__m256i hn_vec  = _mm256_max_epi16(hn_vec0, mn_vec); \
+	en_vec = _mm256_max_epi16(en_vec, zero_vec); \
+	fn_vec = _mm256_max_epi16(fn_vec, zero_vec); \
+	mn_vec = _mm256_max_epi16(mn_vec, zero_vec); \
+	hn_vec = _mm256_max_epi16(hn_vec, zero_vec); 
+
+// 存储向量化结果
+#define SIMD_STORE \
+	max_vec = _mm256_max_epi16(max_vec, hn_vec); \
+	_mm256_storeu_si256((__m256i*)&eA2[j], en_vec); \
+	_mm256_storeu_si256((__m256i*)&fA2[j], fn_vec); \
+	_mm256_storeu_si256((__m256i*)&mA2[j], mn_vec); \
+	_mm256_storeu_si256((__m256i*)&hA2[j], hn_vec);
+
+// 去除多余的部分
+#define SIMD_REMOVE_EXTRA \
+    en_vec = _mm256_and_si256(en_vec, h_vec_mask[end-j]); \
+    fn_vec = _mm256_and_si256(fn_vec, h_vec_mask[end-j]); \
+    mn_vec = _mm256_and_si256(mn_vec, h_vec_mask[end-j]); \
+    hn_vec = _mm256_and_si256(hn_vec, h_vec_mask[end-j]);
+
+// 找最大值和位置
+#define SIMD_FIND_MAX \
+	max_vec = _mm256_max_epu16(max_vec, _mm256_alignr_epi8(max_vec, max_vec, 2)); \
+	max_vec = _mm256_max_epu16(max_vec, _mm256_alignr_epi8(max_vec, max_vec, 4)); \
+	max_vec = _mm256_max_epu16(max_vec, _mm256_alignr_epi8(max_vec, max_vec, 6)); \
+	max_vec = _mm256_max_epu16(max_vec, _mm256_alignr_epi8(max_vec, max_vec, 8)); \
+	max_vec = _mm256_max_epu16(max_vec, _mm256_permute2x128_si256(max_vec, max_vec, 0x01)); \
+	int16_t *maxVal = (int16_t*)&max_vec; \
+    m = maxVal[0]; \
+    if (m > 0) { \
+        for(j=beg, i=iend; j<=end; j+=SIMD_WIDTH, i-=SIMD_WIDTH) { \
+            __m256i h2_vec = _mm256_loadu_si256((__m256i*) (&hA2[j])); \
+            __m256i vcmp = _mm256_cmpeq_epi16(h2_vec, max_vec); \
+            uint32_t mask = _mm256_movemask_epi8(vcmp); \
+            if (mask > 0) { \
+                int pos = SIMD_WIDTH - 1 - (( __builtin_clz(mask)) >> 1); \
+                mj = j - 1 + pos; \
+                mi = i - 1 - pos; \
+            } \
+        } \
+    }
+
+// 每轮迭代后，交换数组
+#define SWAP_DATA_POINTER \
+	int16_t * tmp=hA0; \
+	hA0 = hA1; hA1 = hA2; hA2 = tmp; \
+	tmp = eA1; eA1 = eA2; eA2 = tmp; \
+	tmp = fA1; fA1 = fA2; fA2 = tmp; \
+	tmp = mA1; mA1 = mA2; mA2 = tmp;
+
+
+int ksw_extend2_avx2(int qlen, // query length  待匹配段碱基的query长度
+		const uint8_t *query, // read碱基序列
+		int tlen, // target length reference的长度
+		const uint8_t *target, // reference序列
+		int is_left, // 是不是向左扩展
+		int m, // 碱基种类 (5)
+		const int8_t *mat, // 每个位置的query和target的匹配得分 m*m
+		int o_del, // deletion 错配开始的惩罚系数
+		int e_del, // deletion extension的惩罚系数
+		int o_ins, // insertion 错配开始的惩罚系数
+		int e_ins, // insertion extension的惩罚系数SIMD_BTYES
+		int a, // 碱基match时的分数
+		int b, // 碱基mismatch时的惩罚分数（正数）
+		int w, // 提前剪枝系数，w =100   匹配位置和beg的最大距离 
+		int end_bonus,
+		int zdrop,
+		int h0, // 该seed的初始得分（完全匹配query的碱基数）
+		int *_qle, // 匹配得到全局最大得分的碱基在query的位置
+		int *_tle, // 匹配得到全局最大得分的碱基在reference的位置
+		int *_gtle, // query全部匹配上的target的长度
+		int *_gscore, // query的端到端匹配得分
+		int *_max_off, // 取得最大得分时在query和reference上位置差的 最大值
+		buf_t *buf) // 之前已经开辟过的缓存
+{
+	//return ksw_extend2_origin(qlen, query, tlen, target, is_left, m, mat, o_del, e_del, o_ins, e_ins, w, end_bonus, zdrop, h0, _qle, _tle, _gtle, _gscore, _max_off);
+//    fprintf(stderr, "qlen: %d, tlen: %d\n", qlen, tlen);
+    
+	if (qlen * a + h0 < 255) return ksw_extend2_avx2_u8(qlen, query, tlen, target, is_left, m, mat, o_del, e_del, o_ins, e_ins, a, b, w, end_bonus, zdrop, h0, _qle, _tle, _gtle, _gscore, _max_off, buf);
+
+	int16_t *mA,*hA, *eA, *fA, *mA1, *mA2, *hA0, *hA1, *eA1, *fA1, *hA2, *eA2, *fA2; // hA0保存上上个col的H，其他的保存上个H E F M
+	int16_t *seq, *ref;
+	uint8_t *mem;
+	int16_t *qtmem, *vmem;
+	int seq_size = qlen + SIMD_WIDTH, ref_size = tlen + SIMD_WIDTH;
+	int i, iStart, D, j, k, beg, end, max, max_i, max_j, max_ins, max_del, max_ie, gscore, max_off;
+	int Dloop = tlen + qlen; // 循环跳出条件
+	int span, beg1, end1; // 边界条件计算
+	int col_size = qlen + 2 + SIMD_WIDTH;
+	int val_mem_size = (col_size * 9 * 2 + 31) >> 5 << 5; // 32字节的整数倍
+	int mem_size = (seq_size + ref_size) * 2 + val_mem_size;
+
+	SIMD_INIT; // 初始化simd用的数据
+
+	assert(h0 > 0);
+
+	// allocate memory
+	//mem = malloc(mem_size);
+
+	if (buf->m < mem_size) {
+		buf->m = mem_size;
+		buf->addr = realloc(buf->addr, mem_size);
+	}
+	mem = buf->addr;
+
+	qtmem = (int16_t *)&mem[0];
+	seq=&qtmem[0]; ref=&qtmem[seq_size];
+	if (is_left) {
+		for (i=0; i<qlen; ++i) seq[i] = query[qlen - 1 - i];
+		for (i=0; i<tlen; ++i) ref[i+SIMD_WIDTH] = target[tlen - 1 - i];
+	} else {
+		for (i=0; i<qlen; ++i) seq[i] = query[i];
+		for (i=0; i<tlen; ++i) ref[i+SIMD_WIDTH] = target[i];
+	}
+
+	vmem = &ref[ref_size];
+	for (i=0; i<(val_mem_size>>1); i+=SIMD_WIDTH) {
+		_mm256_storeu_si256((__m256i*)&vmem[i], zero_vec);
+	}
+	hA = &vmem[0];
+	mA = &vmem[col_size * 3];
+	eA = &vmem[col_size * 5];
+	fA = &vmem[col_size * 7];
+
+	hA0 = &hA[0]; hA1 = &hA[col_size]; hA2 = &hA1[col_size];
+	mA1 = &mA[0]; mA2 = &mA[col_size];
+	eA1 = &eA[0]; eA2 = &eA[col_size];
+	fA1 = &fA[0]; fA2 = &fA[col_size];
+
+	// adjust $w if it is too large
+	k = m * m;
+	// get the max score
+	for (i = 0, max = 0; i < k; ++i) max = max > mat[i]? max : mat[i];
+	max_ins = (int)((double)(qlen * max + end_bonus - o_ins) / e_ins + 1.);
+	max_ins = max_ins > 1? max_ins : 1;
+	w = w < max_ins? w : max_ins;
+	max_del = (int)((double)(qlen * max + end_bonus - o_del) / e_del + 1.);
+	max_del = max_del > 1? max_del : 1;
+	w = w < max_del? w : max_del; // TODO: is this necessary?
+	if (tlen < qlen) w = MIN(tlen - 1, w);
+
+	// DP loop
+	max = h0, max_i = max_j = -1; max_ie = -1, gscore = -1;;
+	max_off = 0;
+	beg = 1; end = qlen;
+	// init h0
+	hA0[0] = h0; // 左上角
+
+	if (qlen == 0 || tlen == 0) Dloop = 0; // 防止意外情况
+    if (w >= qlen) { max_ie = 0; gscore = 0; }
+
+	int m_last=0;
+    int iend;
+
+	for (D = 1; LIKELY(D < Dloop); ++D) {
+		// 边界条件一定要注意！ tlen 大于，等于，小于 qlen时的情况
+		if (D > tlen) {
+			span = MIN(Dloop-D, w);
+			beg1 = MAX(D-tlen+1, ((D-w) / 2) + 1);
+		} else {
+			span = MIN(D-1, w);
+			beg1 = MAX(1, ((D-w) / 2) + 1);
+		}
+		end1 = MIN(qlen, beg1+span);
+
+		if (beg < beg1) beg = beg1;
+		if (end > end1) end = end1;
+		if (beg > end) break; // 不用计算了，直接跳出，否则hA2没有被赋值，里边是上一轮hA0的值，会出bug
+
+        iend = D - (beg - 1); // ref开始计算的位置，倒序
+		span = end - beg;
+		iStart = iend - span - 1; // 0开始的ref索引位置
+
+		// 每一轮需要记录的数据
+		int m = 0, mj = -1, mi = -1;
+	    max_vec = zero_vec;
+
+		// 要处理边界
+		// 左边界 处理f (insert)
+		if (iStart == 0) { hA1[end] = MAX(0, h0 - (o_ins + e_ins * end)); }
+		// 上边界
+		if (beg == 1) { hA1[0] = MAX(0, h0 - (o_del + e_del * iend)); } 
+        else { hA1[beg-1] = 0; eA1[beg-1] = 0; }
+
+		for (j=beg, i=iend; j<=end+1-SIMD_WIDTH; j+=SIMD_WIDTH, i-=SIMD_WIDTH) {
+			// 取数据
+			SIMD_LOAD;
+			// 比对seq，计算罚分
+			SIMD_CMP_SEQ;
+			// 计算
+			SIMD_COMPUTE;
+			// 存储结果
+			SIMD_STORE;
+		}
+		// 剩下的计算单元
+		if (j <= end) {
+			// 取数据
+			SIMD_LOAD;
+			// 比对seq，计算罚分
+			SIMD_CMP_SEQ;
+			// 计算
+			SIMD_COMPUTE;
+			// 去除多余计算的部分
+            SIMD_REMOVE_EXTRA;
+			// 存储结果
+			SIMD_STORE;
+		}
+
+		SIMD_FIND_MAX;
+
+		// 注意最后跳出循环j的值
+		j = end + 1;
+
+		if (j == qlen + 1) {
+			max_ie = gscore > hA2[qlen] ? max_ie : iStart;
+			gscore = gscore > hA2[qlen] ? gscore : hA2[qlen];
+		}
+		if (m == 0 && m_last==0) break; // 一定要注意，斜对角遍历和按列遍历的不同点
+		if (m > max) {
+			max = m, max_i = mi, max_j = mj;
+			max_off = max_off > abs(mj - mi)? max_off : abs(mj - mi);
+		}
+		else if (zdrop > 0) {
+			if (mi - max_i > mj - max_j) {
+				if (max - m - ((mi - max_i) - (mj - max_j)) * e_del > zdrop) break;
+			} else {
+				if (max - m - ((mj - max_j) - (mi - max_i)) * e_ins > zdrop) break;
+			}
+		}
+
+		// 调整计算的边界
+		for (j = beg; LIKELY(j <= end); ++j) { int has_val = hA1[j-1] | hA2[j]; if (has_val) break; }
+        beg = j;
+		for (j = end+1; LIKELY(j >= beg); --j) { int has_val = hA1[j-1] | hA2[j]; if (has_val) break; else hA0[j-1]=0; }
+		end = j + 1 <= qlen? j + 1 : qlen;
+
+        m_last = m;
+		// swap m, h, e, f
+		SWAP_DATA_POINTER;
+	}
+
+//	free(mem);
+    if (_qle) *_qle = max_j + 1;
+    if (_tle) *_tle = max_i + 1;
+    if (_gtle) *_gtle = max_ie + 1;
+    if (_gscore) *_gscore = gscore;
+    if (_max_off) *_max_off = max_off;
+	return max;
+}
+
+typedef struct {
+	int32_t h, e;
+} eh_t;
+
+int ksw_extend2_origin(int qlen, // query length  待匹配段碱基的query长度
+                const uint8_t *query, // read碱基序列
+                int tlen, // target length reference的长度
+                const uint8_t *target, // reference序列
+				int is_left, // 是不是向左扩展
+                int m, // 碱基种类 (5)
+                const int8_t *mat, // 每个位置的query和target的匹配得分 m*m
+                int o_del, // deletion 错配开始的惩罚系数
+                int e_del, // deletion extension的惩罚系数
+                int o_ins, // insertion 错配开始的惩罚系数
+                int e_ins, // insertion extension的惩罚系数
+                int w, // 提前剪枝系数，w =100   匹配位置和beg的最大距离 
+                int end_bonus, 
+                int zdrop, 
+                int h0, // 该seed的初始得分（完全匹配query的碱基数）
+                int *_qle, // 匹配得到全局最大得分的碱基在query的位置
+                int *_tle, // 匹配得到全局最大得分的碱基在reference的位置
+                int *_gtle, // query全部匹配上的target的长度
+                int *_gscore, // query的端到端匹配得分
+                int *_max_off) // 取得最大得分时在query和reference上位置差的 最大值
+{
+	eh_t *eh; // score array
+	int8_t *qp; // query profile
+	int i, j, k, oe_del = o_del + e_del, oe_ins = o_ins + e_ins, beg, end, max, max_i, max_j, max_ins, max_del, max_ie, gscore, max_off;
+	uint8_t *qmem, *ref, *seq;
+	assert(h0 > 0);
+	// allocate memory
+	qp = malloc(qlen * m);
+	eh = calloc(qlen + 1, 8);
+	qmem = malloc(qlen + tlen);
+	seq=(uint8_t*)&qmem[0]; ref=(uint8_t*)&qmem[qlen];
+	if (is_left) {
+		for (i=0; i<qlen; ++i) seq[i] = query[qlen - 1 - i];
+		for (i=0; i<tlen; ++i) ref[i] = target[tlen - 1 - i];
+	} else {
+		for (i=0; i<qlen; ++i) seq[i] = query[i];
+		for (i=0; i<tlen; ++i) ref[i] = target[i];
+	}
+	// generate the query profile
+	for (k = i = 0; k < m; ++k) {
+		const int8_t *p = &mat[k * m];
+		for (j = 0; j < qlen; ++j) qp[i++] = p[seq[j]];
+	}
+	// fill the first row
+	eh[0].h = h0; eh[1].h = h0 > oe_ins? h0 - oe_ins : 0;
+	for (j = 2; j <= qlen && eh[j-1].h > e_ins; ++j)
+		eh[j].h = eh[j-1].h - e_ins;
+	// adjust $w if it is too large
+	k = m * m;
+	for (i = 0, max = 0; i < k; ++i) // get the max score
+		max = max > mat[i]? max : mat[i];
+	max_ins = (int)((double)(qlen * max + end_bonus - o_ins) / e_ins + 1.);
+	max_ins = max_ins > 1? max_ins : 1;
+	w = w < max_ins? w : max_ins;
+	max_del = (int)((double)(qlen * max + end_bonus - o_del) / e_del + 1.);
+	max_del = max_del > 1? max_del : 1;
+	w = w < max_del? w : max_del; // TODO: is this necessary?
+//    printf("%d\n", w);
+	// DP loop
+	max = h0, max_i = max_j = -1; max_ie = -1, gscore = -1;
+	max_off = 0;
+	beg = 0, end = qlen;
+
+	for (i = 0; LIKELY(i < tlen); ++i) {
+		int t, f = 0, h1, m = 0, mj = -1;
+		int8_t *q = &qp[ref[i] * qlen];
+		// apply the band and the constraint (if provided)
+		if (beg < i - w) beg = i - w;
+		if (end > i + w + 1) end = i + w + 1;
+		//if (end > qlen) end = qlen; 没用
+		// compute the first column
+		if (beg == 0) {
+			h1 = h0 - (o_del + e_del * (i + 1));
+			if (h1 < 0) h1 = 0;
+		} else h1 = 0;
+		for (j = beg; LIKELY(j < end); ++j) {
+			// At the beginning of the loop: eh[j] = { H(i-1,j-1), E(i,j) }, f = F(i,j) and h1 = H(i,j-1)
+			// Similar to SSE2-SW, cells are computed in the following order:
+			//   H(i,j)   = max{H(i-1,j-1)+S(i,j), E(i,j), F(i,j)}
+			//   E(i+1,j) = max{H(i,j)-gapo, E(i,j)} - gape
+			//   F(i,j+1) = max{H(i,j)-gapo, F(i,j)} - gape
+			eh_t *p = &eh[j];
+			int h, M = p->h, e = p->e; // get H(i-1,j-1) and E(i-1,j)
+			p->h = h1;          // set H(i,j-1) for the next row
+			M = M? M + q[j] : 0;// separating H and M to disallow a cigar like "100M3I3D20M"
+			h = M > e? M : e;   // e and f are guaranteed to be non-negative, so h>=0 even if M<0
+			h = h > f? h : f;
+			h1 = h;             // save H(i,j) to h1 for the next column
+			mj = m > h? mj : j; // record the position where max score is achieved
+			m = m > h? m : h;   // m is stored at eh[mj+1]
+			t = M - oe_del;
+			t = t > 0? t : 0;
+			e -= e_del;
+			e = e > t? e : t;   // computed E(i+1,j)
+			p->e = e;           // save E(i+1,j) for the next row
+			t = M - oe_ins;
+			t = t > 0? t : 0;
+			f -= e_ins;
+			f = f > t? f : t;   // computed F(i,j+1)
+		}
+		eh[end].h = h1; eh[end].e = 0;
+		if (j == qlen) {
+			max_ie = gscore > h1? max_ie : i;
+			gscore = gscore > h1? gscore : h1;
+		}
+		if (m == 0) break;
+		if (m > max) {
+			max = m, max_i = i, max_j = mj;
+			max_off = max_off > abs(mj - i)? max_off : abs(mj - i);
+		} else if (zdrop > 0) {
+			if (i - max_i > mj - max_j) {
+				if (max - m - ((i - max_i) - (mj - max_j)) * e_del > zdrop) break;
+			} else {
+				if (max - m - ((mj - max_j) - (i - max_i)) * e_ins > zdrop) break;
+			}
+		}
+		// update beg and end for the next round
+		for (j = beg; LIKELY(j < end) && eh[j].h == 0 && eh[j].e == 0; ++j);
+		beg = j;
+		for (j = end; LIKELY(j >= beg) && eh[j].h == 0 && eh[j].e == 0; --j);
+		end = j + 2 < qlen? j + 2 : qlen;
+		//beg = 0; end = qlen; // uncomment this line for debugging
+	}
+
+	free(eh); free(qp); free(qmem);
+	if (_qle) *_qle = max_j + 1;
+	if (_tle) *_tle = max_i + 1;
+	if (_gtle) *_gtle = max_ie + 1;
+	if (_gscore) *_gscore = gscore;
+	if (_max_off) *_max_off = max_off;
+	return max;
+}
diff --git a/ksw_extend2_avx2_u8.c b/ksw_extend2_avx2_u8.c
new file mode 100644
index 0000000..7c0d49a
--- /dev/null
+++ b/ksw_extend2_avx2_u8.c
@@ -0,0 +1,379 @@
+#include <stdlib.h>
+#include <stdint.h>
+#include <assert.h>
+#include <emmintrin.h>
+#include <stdio.h>
+#include <immintrin.h>
+#include <emmintrin.h>
+
+#ifdef __GNUC__
+#define LIKELY(x) __builtin_expect((x),1)
+#define UNLIKELY(x) __builtin_expect((x),0)
+#else
+#define LIKELY(x) (x)
+#define UNLIKELY(x) (x)
+#endif
+
+#undef MAX
+#undef MIN
+#define MAX(x, y) ((x) > (y) ? (x) : (y))
+#define MIN(x, y) ((x) < (y) ? (x) : (y))
+#define SIMD_WIDTH 32
+
+typedef struct { size_t m; uint8_t *addr; } buf_t;
+
+static const uint8_t h_vec_int_mask[SIMD_WIDTH][SIMD_WIDTH] = {
+	{0xff, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0},
+	{0xff, 0xff, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0},
+	{0xff, 0xff, 0xff, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0},
+	{0xff, 0xff, 0xff, 0xff, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0},
+	{0xff, 0xff, 0xff, 0xff, 0xff, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0},
+	{0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0},
+	{0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0},
+	{0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0},
+	{0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0},
+	{0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0},
+	{0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0},
+	{0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0},
+	{0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0},
+	{0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0},
+	{0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0},
+	{0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0},
+	{0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0},
+	{0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0},
+	{0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0},
+	{0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0},
+	{0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0},
+	{0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0},
+	{0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0, 0, 0, 0, 0, 0, 0, 0, 0},
+	{0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0, 0, 0, 0, 0, 0, 0, 0},
+	{0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0, 0, 0, 0, 0, 0, 0},
+	{0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0, 0, 0, 0, 0, 0},
+	{0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0, 0, 0, 0, 0},
+	{0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0, 0, 0, 0},
+	{0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0, 0, 0},
+	{0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0, 0},
+	{0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0},
+	{0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff}
+};
+
+//static const uint8_t reverse_mask[SIMD_WIDTH] = {1, 0, 3, 2, 5, 4, 7, 6, 9, 8, 11, 10, 13, 12, 15, 14, 1, 0, 3, 2, 5, 4, 7, 6, 9, 8, 11, 10, 13, 12, 15, 14};
+static const uint8_t reverse_mask[SIMD_WIDTH] = {7,6,5,4,3,2,1,0,15,14,13,12,11,10,9,8,7,6,5,4,3,2,1,0,15,14,13,12,11,10,9,8};
+#define permute_mask _MM_SHUFFLE(0, 1, 2, 3)
+//const int permute_mask = _MM_SHUFFLE(0, 1, 2, 3);
+// 初始化变量
+#define SIMD_INIT \
+	int oe_del = o_del + e_del, oe_ins = o_ins + e_ins; \
+	__m256i zero_vec; \
+	__m256i max_vec; \
+	__m256i oe_del_vec; \
+	__m256i oe_ins_vec; \
+	__m256i e_del_vec; \
+	__m256i e_ins_vec; \
+	__m256i h_vec_mask[SIMD_WIDTH]; \
+    __m256i reverse_mask_vec; \
+	zero_vec = _mm256_setzero_si256(); \
+	oe_del_vec = _mm256_set1_epi8(oe_del); \
+	oe_ins_vec = _mm256_set1_epi8(oe_ins); \
+	e_del_vec = _mm256_set1_epi8(e_del); \
+	e_ins_vec = _mm256_set1_epi8(e_ins); \
+	__m256i match_sc_vec = _mm256_set1_epi8(a); \
+	__m256i mis_sc_vec = _mm256_set1_epi8(b); \
+	__m256i amb_sc_vec = _mm256_set1_epi8(1); \
+	__m256i amb_vec = _mm256_set1_epi8(4); \
+    reverse_mask_vec = _mm256_loadu_si256((__m256i*) (reverse_mask)); \
+	for (i=0; i<SIMD_WIDTH; ++i) h_vec_mask[i] =  _mm256_loadu_si256((__m256i*) (&h_vec_int_mask[i]));
+
+/*
+ * e 表示当前ref的碱基被删除
+ * f 表示当前seq的碱基插入
+ * m 表示当前碱基匹配（可以相等，也可以不想等）
+ * h 表示最大值
+ */
+// load向量化数据
+#define SIMD_LOAD \
+	__m256i m1 = _mm256_loadu_si256((__m256i*) (&mA1[j])); \
+	__m256i e1 = _mm256_loadu_si256((__m256i*) (&eA1[j])); \
+	__m256i m1j1 = _mm256_loadu_si256((__m256i*) (&mA1[j-1])); \
+	__m256i f1j1 = _mm256_loadu_si256((__m256i*) (&fA1[j-1])); \
+	__m256i h0j1 = _mm256_loadu_si256((__m256i*) (&hA0[j-1])); \
+	__m256i qs_vec = _mm256_loadu_si256((__m256i*) (&seq[j-1])); \
+	__m256i ts_vec = _mm256_loadu_si256((__m256i*) (&ref[i]));
+
+// 比对ref和seq的序列，计算罚分
+#define SIMD_CMP_SEQ \
+	ts_vec = _mm256_permute4x64_epi64(ts_vec, permute_mask); \
+    ts_vec = _mm256_shuffle_epi8(ts_vec, reverse_mask_vec); \
+	__m256i match_mask_vec = _mm256_cmpeq_epi8(qs_vec, ts_vec); \
+	__m256i mis_score_vec  = _mm256_andnot_si256(match_mask_vec, mis_sc_vec); \
+	__m256i match_score_vec   = _mm256_and_si256(match_sc_vec, match_mask_vec); \
+	__m256i q_amb_mask_vec = _mm256_cmpeq_epi8(qs_vec, amb_vec); \
+	__m256i t_amb_mask_vec = _mm256_cmpeq_epi8(ts_vec, amb_vec); \
+	__m256i amb_mask_vec   = _mm256_or_si256(q_amb_mask_vec, t_amb_mask_vec); \
+	__m256i amb_score_vec  = _mm256_and_si256(amb_mask_vec, amb_sc_vec); \
+    mis_score_vec = _mm256_andnot_si256(amb_mask_vec, mis_score_vec); \
+    mis_score_vec = _mm256_or_si256(amb_score_vec, mis_score_vec); \
+    match_score_vec = _mm256_andnot_si256(amb_mask_vec, match_score_vec);
+
+// 向量化计算h, e, f, m
+#define SIMD_COMPUTE \
+	__m256i en_vec0 = _mm256_max_epu8(m1, oe_del_vec); \
+    en_vec0 = _mm256_subs_epu8(en_vec0, oe_del_vec); \
+	__m256i en_vec1 = _mm256_max_epu8(e1, e_del_vec); \
+    en_vec1 = _mm256_subs_epu8(en_vec1, e_del_vec); \
+	__m256i en_vec  = _mm256_max_epu8(en_vec0, en_vec1); \
+	__m256i fn_vec0 = _mm256_max_epu8(m1j1, oe_ins_vec); \
+    fn_vec0 = _mm256_subs_epu8(fn_vec0, oe_ins_vec); \
+	__m256i fn_vec1 = _mm256_max_epu8(f1j1, e_ins_vec); \
+    fn_vec1 = _mm256_subs_epu8(fn_vec1, e_ins_vec); \
+	__m256i fn_vec  = _mm256_max_epu8(fn_vec0, fn_vec1); \
+	__m256i mn_vec0 = _mm256_adds_epu8(h0j1, match_score_vec); \
+    mn_vec0 = _mm256_max_epu8(mn_vec0, mis_score_vec); \
+    mn_vec0 = _mm256_subs_epu8(mn_vec0, mis_score_vec); \
+	__m256i mn_mask = _mm256_cmpeq_epi8(h0j1, zero_vec); \
+	__m256i mn_vec  = _mm256_andnot_si256(mn_mask, mn_vec0); \
+	__m256i hn_vec0 = _mm256_max_epu8(en_vec, fn_vec); \
+	__m256i hn_vec  = _mm256_max_epu8(hn_vec0, mn_vec); 
+
+// 存储向量化结果
+#define SIMD_STORE \
+	max_vec = _mm256_max_epu8(max_vec, hn_vec); \
+	_mm256_storeu_si256((__m256i*)&eA2[j], en_vec); \
+	_mm256_storeu_si256((__m256i*)&fA2[j], fn_vec); \
+	_mm256_storeu_si256((__m256i*)&mA2[j], mn_vec); \
+	_mm256_storeu_si256((__m256i*)&hA2[j], hn_vec);
+
+// 去除多余的部分
+#define SIMD_REMOVE_EXTRA \
+    en_vec = _mm256_and_si256(en_vec, h_vec_mask[end-j]); \
+    fn_vec = _mm256_and_si256(fn_vec, h_vec_mask[end-j]); \
+    mn_vec = _mm256_and_si256(mn_vec, h_vec_mask[end-j]); \
+    hn_vec = _mm256_and_si256(hn_vec, h_vec_mask[end-j]);
+
+// 找最大值和位置
+#define SIMD_FIND_MAX \
+	uint8_t *maxVal = (uint8_t*)&max_vec; \
+	max_vec = _mm256_max_epu8(max_vec, _mm256_alignr_epi8(max_vec, max_vec, 1)); \
+	max_vec = _mm256_max_epu8(max_vec, _mm256_alignr_epi8(max_vec, max_vec, 2)); \
+	max_vec = _mm256_max_epu8(max_vec, _mm256_alignr_epi8(max_vec, max_vec, 3)); \
+	max_vec = _mm256_max_epu8(max_vec, _mm256_alignr_epi8(max_vec, max_vec, 4)); \
+	max_vec = _mm256_max_epu8(max_vec, _mm256_alignr_epi8(max_vec, max_vec, 5)); \
+	max_vec = _mm256_max_epu8(max_vec, _mm256_alignr_epi8(max_vec, max_vec, 6)); \
+	max_vec = _mm256_max_epu8(max_vec, _mm256_alignr_epi8(max_vec, max_vec, 7)); \
+	max_vec = _mm256_max_epu8(max_vec, _mm256_alignr_epi8(max_vec, max_vec, 8)); \
+	max_vec = _mm256_max_epu8(max_vec, _mm256_permute2x128_si256(max_vec, max_vec, 0x01)); \
+    m = maxVal[0]; \
+    if (m > 0) { \
+        for(j=beg, i=iend; j<=end; j+=SIMD_WIDTH, i-=SIMD_WIDTH) { \
+            __m256i h2_vec = _mm256_loadu_si256((__m256i*) (&hA2[j])); \
+            __m256i vcmp = _mm256_cmpeq_epi8(h2_vec, max_vec); \
+            uint32_t mask = _mm256_movemask_epi8(vcmp); \
+            if (mask > 0) { \
+                int pos = SIMD_WIDTH - 1 - __builtin_clz(mask); \
+                mj = j - 1 + pos; \
+                mi = i - 1 - pos; \
+            } \
+        } \
+    }
+
+// 每轮迭代后，交换数组
+#define SWAP_DATA_POINTER \
+	uint8_t * tmp=hA0; \
+	hA0 = hA1; hA1 = hA2; hA2 = tmp; \
+	tmp = eA1; eA1 = eA2; eA2 = tmp; \
+	tmp = fA1; fA1 = fA2; fA2 = tmp; \
+	tmp = mA1; mA1 = mA2; mA2 = tmp;
+
+
+int ksw_extend2_avx2_u8(int qlen, // query length  待匹配段碱基的query长度
+		const uint8_t *query, // read碱基序列
+		int tlen, // target length reference的长度
+		const uint8_t *target, // reference序列
+		int is_left, // 是不是向左扩展
+		int m, // 碱基种类 (5)
+		const int8_t *mat, // 每个位置的query和target的匹配得分 m*m
+		int o_del, // deletion 错配开始的惩罚系数
+		int e_del, // deletion extension的惩罚系数
+		int o_ins, // insertion 错配开始的惩罚系数
+		int e_ins, // insertion extension的惩罚系数
+		int a, // 碱基match时的分数
+		int b, // 碱基mismatch时的惩罚分数（正数）
+		int w, // 提前剪枝系数，w =100   匹配位置和beg的最大距离 
+		int end_bonus, 
+		int zdrop, 
+		int h0, // 该seed的初始得分（完全匹配query的碱基数）
+		int *_qle, // 匹配得到全局最大得分的碱基在query的位置
+		int *_tle, // 匹配得到全局最大得分的碱基在reference的位置
+		int *_gtle, // query全部匹配上的target的长度
+		int *_gscore, // query的端到端匹配得分
+		int *_max_off, // 取得最大得分时在query和reference上位置差的 最大值
+		buf_t *buf) // 之前已经开辟过的缓存
+{
+	uint8_t *mA,*hA, *eA, *fA, *mA1, *mA2, *hA0, *hA1, *eA1, *fA1, *hA2, *eA2, *fA2; // hA0保存上上个col的H，其他的保存上个H E F M
+	uint8_t *seq, *ref;
+	uint8_t *mem, *qtmem, *vmem;
+	int seq_size = qlen + SIMD_WIDTH, ref_size = tlen + SIMD_WIDTH;
+	int i, iStart, D, j, k, beg, end, max, max_i, max_j, max_ins, max_del, max_ie, gscore, max_off;
+	int Dloop = tlen + qlen; // 循环跳出条件
+	int span, beg1, end1; // 边界条件计算
+	int col_size = qlen + 2 + SIMD_WIDTH;
+	int val_mem_size = (col_size * 9 + 31) >> 5 << 5; // 32字节的整数倍
+	int mem_size = seq_size + ref_size + val_mem_size;
+
+	SIMD_INIT; // 初始化simd用的数据
+
+	assert(h0 > 0);
+
+	// allocate memory
+	//mem = malloc(mem_size);
+	if (buf->m < mem_size) {
+		buf->m = mem_size;
+		buf->addr = realloc(buf->addr, mem_size);
+	}
+	mem = buf->addr;
+
+	qtmem = &mem[0];
+	seq=(uint8_t*)&qtmem[0]; ref=(uint8_t*)&qtmem[seq_size];
+	if (is_left) {
+		for (i=0; i<qlen; ++i) seq[i] = query[qlen - 1 - i];
+		for (i=0; i<tlen; ++i) ref[i+SIMD_WIDTH] = target[tlen - 1 - i];
+	} else {
+		for (i=0; i<qlen; ++i) seq[i] = query[i];
+		for (i=0; i<tlen; ++i) ref[i+SIMD_WIDTH] = target[i];
+	}
+
+	vmem = &ref[ref_size];
+	for (i=0; i<val_mem_size; i+=SIMD_WIDTH) {
+		_mm256_storeu_si256((__m256i*)&vmem[i], zero_vec);
+	}
+
+	hA = &vmem[0];
+	mA = &vmem[col_size * 3];
+	eA = &vmem[col_size * 5];
+	fA = &vmem[col_size * 7];
+
+	hA0 = &hA[0]; hA1 = &hA[col_size]; hA2 = &hA1[col_size];
+	mA1 = &mA[0]; mA2 = &mA[col_size];
+	eA1 = &eA[0]; eA2 = &eA[col_size];
+	fA1 = &fA[0]; fA2 = &fA[col_size];
+
+	// adjust $w if it is too large
+	k = m * m;
+	// get the max score
+	for (i = 0, max = 0; i < k; ++i) max = max > mat[i]? max : mat[i];
+	max_ins = (int)((double)(qlen * max + end_bonus - o_ins) / e_ins + 1.);
+	max_ins = max_ins > 1? max_ins : 1;
+	w = w < max_ins? w : max_ins;
+	max_del = (int)((double)(qlen * max + end_bonus - o_del) / e_del + 1.);
+	max_del = max_del > 1? max_del : 1;
+	w = w < max_del? w : max_del; // TODO: is this necessary?
+	if (tlen < qlen) w = MIN(tlen - 1, w);
+
+	// DP loop
+	max = h0, max_i = max_j = -1; max_ie = -1, gscore = -1;;
+	max_off = 0;
+	beg = 1; end = qlen;
+	// init h0
+	hA0[0] = h0; // 左上角
+
+	if (qlen == 0 || tlen == 0) Dloop = 0; // 防止意外情况
+    if (w >= qlen) { max_ie = 0; gscore = 0; }
+
+	int m_last=0;
+    int iend;
+
+	for (D = 1; LIKELY(D < Dloop); ++D) {
+		// 边界条件一定要注意！ tlen 大于，等于，小于 qlen时的情况
+		if (D > tlen) {
+			span = MIN(Dloop-D, w);
+			beg1 = MAX(D-tlen+1, ((D-w) / 2) + 1);
+		} else {
+			span = MIN(D-1, w);
+			beg1 = MAX(1, ((D-w) / 2) + 1);
+		}
+		end1 = MIN(qlen, beg1+span);
+
+		if (beg < beg1) beg = beg1;
+		if (end > end1) end = end1;
+		if (beg > end) break; // 不用计算了，直接跳出，否则hA2没有被赋值，里边是上一轮hA0的值，会出bug
+
+        iend = D - (beg - 1); // ref开始计算的位置，倒序
+		span = end - beg;
+		iStart = iend - span - 1; // 0开始的ref索引位置
+
+		// 每一轮需要记录的数据
+		int m = 0, mj = -1, mi = -1;
+	    max_vec = zero_vec;
+
+		// 要处理边界
+		// 左边界 处理f (insert)
+		if (iStart == 0) { hA1[end] = MAX(0, h0 - (o_ins + e_ins * end)); }
+		// 上边界
+		if (beg == 1) { hA1[0] = MAX(0, h0 - (o_del + e_del * iend)); } 
+        else { hA1[beg-1] = 0; eA1[beg-1] = 0; }
+
+		for (j=beg, i=iend; j<=end+1-SIMD_WIDTH; j+=SIMD_WIDTH, i-=SIMD_WIDTH) {
+			// 取数据
+			SIMD_LOAD;
+			// 比对seq，计算罚分
+			SIMD_CMP_SEQ;
+			// 计算
+			SIMD_COMPUTE;
+			// 存储结果
+			SIMD_STORE;
+		}
+		// 剩下的计算单元
+		if (j <= end) {
+			// 取数据
+			SIMD_LOAD;
+			// 比对seq，计算罚分
+			SIMD_CMP_SEQ;
+			// 计算
+			SIMD_COMPUTE;
+			// 去除多余计算的部分
+            SIMD_REMOVE_EXTRA;
+			// 存储结果
+			SIMD_STORE;
+		}
+
+		SIMD_FIND_MAX;
+
+		// 注意最后跳出循环j的值
+		j = end + 1;
+
+		if (j == qlen + 1) {
+			max_ie = gscore > hA2[qlen] ? max_ie : iStart;
+			gscore = gscore > hA2[qlen] ? gscore : hA2[qlen];
+		}
+		if (m == 0 && m_last==0) break; // 一定要注意，斜对角遍历和按列遍历的不同点
+		if (m > max) {
+			max = m, max_i = mi, max_j = mj;
+			max_off = max_off > abs(mj - mi)? max_off : abs(mj - mi);
+		}
+		else if (zdrop > 0) {
+			if (mi - max_i > mj - max_j) {
+				if (max - m - ((mi - max_i) - (mj - max_j)) * e_del > zdrop) break;
+			} else {
+				if (max - m - ((mj - max_j) - (mi - max_i)) * e_ins > zdrop) break;
+			}
+		}
+
+		// 调整计算的边界
+		for (j = beg; LIKELY(j <= end); ++j) { int has_val = hA1[j-1] | hA2[j]; if (has_val) break; }
+        beg = j;
+		for (j = end+1; LIKELY(j >= beg); --j) { int has_val = hA1[j-1] | hA2[j]; if (has_val) break; else hA0[j-1]=0; }
+		end = j + 1 <= qlen? j + 1 : qlen;
+
+        m_last = m;
+		// swap m, h, e, f
+		SWAP_DATA_POINTER;
+	}
+
+//	free(mem);
+    if (_qle) *_qle = max_j + 1;
+    if (_tle) *_tle = max_i + 1;
+    if (_gtle) *_gtle = max_ie + 1;
+    if (_gscore) *_gscore = gscore;
+    if (_max_off) *_max_off = max_off;
+	return max;
+}
diff --git a/pemerge.c b/pemerge.c
index 725885f..197e87f 100644
--- a/pemerge.c
+++ b/pemerge.c
@@ -216,9 +216,9 @@ static void process_seqs(const pem_opt_t *opt, int n_, bseq1_t *seqs, int64_t cn
 
 int main_pemerge(int argc, char *argv[])
 {
-	int c, flag = 0, i, n, min_ovlp = 10;
-	int64_t cnt[MAX_ERR+1];
-	bseq1_t *bseq;
+	int c, flag = 0, i, n, m = 0, min_ovlp = 10;
+	int64_t cnt[MAX_ERR + 1], seq_size = 0;
+	bseq1_t *bseq = 0;
 	gzFile fp, fp2 = 0;
 	kseq_t *ks, *ks2 = 0;
 	pem_opt_t *opt;
@@ -269,10 +269,12 @@ int main_pemerge(int argc, char *argv[])
 	}
 
 	memset(cnt, 0, 8 * (MAX_ERR+1));
-	while ((bseq = bseq_read(opt->n_threads * opt->chunk_size, &n, ks, ks2)) != 0) {
+	bseq_read(opt->n_threads * opt->chunk_size, &n, ks, ks2, 1, &seq_size, &m, &bseq);
+	while (n > 0) {
 		process_seqs(opt, n, bseq, cnt);
-		free(bseq);
+		bseq_read(opt->n_threads * opt->chunk_size, &n, ks, ks2, 1, &seq_size, &m, &bseq);
 	}
+	if (bseq != 0) free(bseq);
 
 	fprintf(stderr, "%12ld %s\n", (long)cnt[0], err_msg[0]);
 	for (i = 1; i <= MAX_ERR; ++i)
diff --git a/run.sh b/run.sh
index 961dc81..b4c21f7 100755
--- a/run.sh
+++ b/run.sh
@@ -6,8 +6,10 @@ thread=1
 #reference=~/data/reference/human_g1k_v37_decoy.fasta
 #n_r1=~/fastq/sn_r1.fq
 #n_r2=~/fastq/sn_r2.fq
-n_r1=~/fastq/ssn_r1.fq
-n_r2=~/fastq/ssn_r2.fq
+#n_r1=~/fastq/ssn_r1.fq
+#n_r2=~/fastq/ssn_r2.fq
+n_r1=~/fastq/ERR194147_1_120w.fastq
+n_r2=~/fastq/ERR194147_2_120w.fastq
 #n_r1=~/fastq/tiny_n_r1.fq
 #n_r2=~/fastq/tiny_n_r2.fq
 #n_r1=~/fastq/diff_r1.fq
@@ -15,9 +17,10 @@ n_r2=~/fastq/ssn_r2.fq
 #n_r1=~/fastq/d_r1.fq
 #n_r2=~/fastq/d_r2.fq
 reference=~/reference/human_g1k_v37_decoy.fasta
-out=./ssn.sam
+#out=./all.sam
+#out=./ssn.sam
 #out=./out.sam
-#out=/dev/null
+out=/dev/null
 #time ./bwa mem -t 12 -M -R @RG\\tID:normal\\tSM:normal\\tPL:illumina\\tLB:normal\\tPG:bwa \
 #    /home/zzh/data/reference/human_g1k_v37_decoy.fasta \
 #    /home/zzh/data/fastq/nm1.fq \
diff --git a/utils.h b/utils.h
index 5722787..52107cc 100644
--- a/utils.h
+++ b/utils.h
@@ -45,7 +45,10 @@ extern int64_t time_ksw_extend2,
 	time_bwt_occ4,
 	time_bwt_sa,
 	time_bwt_sa_read,
-	time_bns;
+	time_bns,
+	time_work1,
+	time_work2,
+	time_flt_chain;
 
 extern int64_t dn, n16, n17, n18, n19, nall, num_sa;
 extern int64_t s1n, s2n, s3n, s1l, s2l, s3l;
@@ -54,6 +57,11 @@ extern FILE *fp1;
 
 #endif
 
+#undef MAX
+#undef MIN
+#define MAX(x, y) ((x) > (y) ? (x) : (y))
+#define MIN(x, y) ((x) < (y) ? (x) : (y))
+
 #ifdef __GNUC__
 // Tell GCC to validate printf format string and args
 #define ATTRIBUTE(list) __attribute__ (list)
@@ -77,6 +85,8 @@ typedef struct {
 typedef struct { size_t n, m; uint64_t *a; } uint64_v;
 typedef struct { size_t n, m; pair64_t *a; } pair64_v;
 
+typedef struct { size_t m; uint8_t *addr; } buf_t;
+
 #ifdef __cplusplus
 extern "C" {
 #endif