Merge branch 'split'

Makefile

@@ -1,7 +1,7 @@
 CFLAGS=		-g -Wall -O2 -Wc++-compat #-Wextra
 CPPFLAGS=	-DHAVE_KALLOC
 INCLUDES=
-OBJS=		kthread.o kalloc.o misc.o bseq.o sketch.o sdust.o options.o index.o chain.o align.o hit.o map.o format.o pe.o esterr.o ksw2_ll_sse.o
+OBJS=		kthread.o kalloc.o misc.o bseq.o sketch.o sdust.o options.o index.o chain.o align.o hit.o map.o format.o pe.o esterr.o splitidx.o ksw2_ll_sse.o
 PROG=		minimap2
 PROG_EXTRA=	sdust minimap2-lite
 LIBS=		-lm -lz -lpthread

align.c

@@ -199,12 +199,12 @@ static void mm_append_cigar(mm_reg1_t *r, uint32_t n_cigar, uint32_t *cigar) //
 	mm_extra_t *p;
 	if (n_cigar == 0) return;
 	if (r->p == 0) {
-		uint32_t capacity = n_cigar + sizeof(mm_extra_t); // TODO: should this be "n_cigar + sizeof(mm_extra_t)/4" instead?
+		uint32_t capacity = n_cigar + sizeof(mm_extra_t)/4;
 		kroundup32(capacity);
 		r->p = (mm_extra_t*)calloc(capacity, 4);
 		r->p->capacity = capacity;
-	} else if (r->p->n_cigar + n_cigar + sizeof(mm_extra_t) > r->p->capacity) {
+	} else if (r->p->n_cigar + n_cigar + sizeof(mm_extra_t)/4 > r->p->capacity) {
-		r->p->capacity = r->p->n_cigar + n_cigar + sizeof(mm_extra_t);
+		r->p->capacity = r->p->n_cigar + n_cigar + sizeof(mm_extra_t)/4;
 		kroundup32(r->p->capacity);
 		r->p = (mm_extra_t*)realloc(r->p, r->p->capacity * 4);
 	}
@@ -878,6 +878,6 @@ mm_reg1_t *mm_align_skeleton(void *km, const mm_mapopt_t *opt, const mm_idx_t *m
 	kfree(km, qseq0[0]);
 	kfree(km, ez.cigar);
 	mm_filter_regs(opt, qlen, n_regs_, regs);
-	mm_hit_sort_by_dp(km, n_regs_, regs);
+	mm_hit_sort(km, n_regs_, regs);
 	return regs;
 }

hit.c

@@ -164,9 +164,9 @@ set_parent_test:
 	kfree(km, w);
 }
 
-void mm_hit_sort_by_dp(void *km, int *n_regs, mm_reg1_t *r)
+void mm_hit_sort(void *km, int *n_regs, mm_reg1_t *r)
 {
-	int32_t i, n_aux, n = *n_regs;
+	int32_t i, n_aux, n = *n_regs, has_cigar = 0, no_cigar = 0;
 	mm128_t *aux;
 	mm_reg1_t *t;
 
@@ -175,14 +175,20 @@ void mm_hit_sort_by_dp(void *km, int *n_regs, mm_reg1_t *r)
 	t = (mm_reg1_t*)kmalloc(km, n * sizeof(mm_reg1_t));
 	for (i = n_aux = 0; i < n; ++i) {
 		if (r[i].inv || r[i].cnt > 0) { // squeeze out elements with cnt==0 (soft deleted)
-			assert(r[i].p);
+			if (r[i].p) {
 				aux[n_aux].x = (uint64_t)r[i].p->dp_max << 32 | r[i].hash;
+				has_cigar = 1;
+			} else {
+				aux[n_aux].x = (uint64_t)r[i].score << 32 | r[i].hash;
+				no_cigar = 1;
+			}
 			aux[n_aux++].y = i;
 		} else if (r[i].p) {
 			free(r[i].p);
 			r[i].p = 0;
 		}
 	}
+	assert(has_cigar + no_cigar == 1);
 	radix_sort_128x(aux, aux + n_aux);
 	for (i = n_aux - 1; i >= 0; --i)
 		t[n_aux - 1 - i] = r[aux[i].y];

index.c

@@ -48,11 +48,13 @@ void mm_idx_destroy(mm_idx_t *mi)
 	uint32_t i;
 	if (mi == 0) return;
 	if (mi->h) kh_destroy(str, (khash_t(str)*)mi->h);
+	if (mi->B) {
 		for (i = 0; i < 1U<<mi->b; ++i) {
 			free(mi->B[i].p);
 			free(mi->B[i].a.a);
 			kh_destroy(idx, (idxhash_t*)mi->B[i].h);
 		}
+	}
 	if (!mi->km) {
 		for (i = 0; i < mi->n_seq; ++i)
 			free(mi->seq[i].name);
@@ -563,7 +565,7 @@ mm_idx_t *mm_idx_reader_read(mm_idx_reader_t *r, int n_threads)
 		mi = mm_idx_gen(r->fp.seq, r->opt.w, r->opt.k, r->opt.bucket_bits, r->opt.flag, r->opt.mini_batch_size, n_threads, r->opt.batch_size);
 	if (mi) {
 		if (r->fp_out) mm_idx_dump(r->fp_out, mi);
-		++r->n_parts;
+		mi->index = r->n_parts++;
 	}
 	return mi;
 }

main.c

@@ -10,7 +10,7 @@
 #include "getopt.h"
 #endif
 
-#define MM_VERSION "2.11-r797"
+#define MM_VERSION "2.11-r815-dirty"
 
 #ifdef __linux__
 #include <sys/resource.h>
@@ -61,6 +61,7 @@ static struct option long_options[] = {
 	{ "score-N",        required_argument, 0, 0 },   // 31
 	{ "eqx",            no_argument,       0, 0 },   // 32
 	{ "paf-no-hit",     no_argument,       0, 0 },   // 33
+	{ "split-prefix",   required_argument, 0, 0 },   // 34
 	{ "help",           no_argument,       0, 'h' },
 	{ "max-intron-len", required_argument, 0, 'G' },
 	{ "version",        no_argument,       0, 'V' },
@@ -101,7 +102,7 @@ int main(int argc, char *argv[])
 	const char *opt_str = "2aSDw:k:K:t:r:f:Vv:g:G:I:d:XT:s:x:Hcp:M:n:z:A:B:O:E:m:N:Qu:R:hF:LC:yY";
 	mm_mapopt_t opt;
 	mm_idxopt_t ipt;
-	int i, c, n_threads = 3, long_idx;
+	int i, c, n_threads = 3, n_parts, long_idx;
 	char *fnw = 0, *rg = 0, *s;
 	FILE *fp_help = stderr;
 	mm_idx_reader_t *idx_rdr;
@@ -181,6 +182,7 @@ int main(int argc, char *argv[])
 		else if (c == 0 && long_idx ==31) opt.sc_ambi = atoi(optarg); // --score-N
 		else if (c == 0 && long_idx ==32) opt.flag |= MM_F_EQX; // --eqx
 		else if (c == 0 && long_idx ==33) opt.flag |= MM_F_PAF_NO_HIT; // --paf-no-hit
+		else if (c == 0 && long_idx ==34) opt.split_prefix = optarg; // --split-prefix
 		else if (c == 0 && long_idx == 14) { // --frag
 			yes_or_no(&opt, MM_F_FRAG_MODE, long_idx, optarg, 1);
 		} else if (c == 0 && long_idx == 15) { // --secondary
@@ -327,8 +329,8 @@ int main(int argc, char *argv[])
 				mm_write_sam_hdr(mi, rg, MM_VERSION, argc, argv);
 			} else {
 				mm_write_sam_hdr(0, rg, MM_VERSION, argc, argv);
-				if (mm_verbose >= 2)
+				if (opt.split_prefix == 0 && mm_verbose >= 2)
-					fprintf(stderr, "[WARNING]\033[1;31m For a multi-part index, no @SQ lines will be outputted.\033[0m\n");
+					fprintf(stderr, "[WARNING]\033[1;31m For a multi-part index, no @SQ lines will be outputted. Please use --split-prefix.\033[0m\n");
 			}
 		}
 		if (mm_verbose >= 3)
@@ -344,8 +346,12 @@ int main(int argc, char *argv[])
 		}
 		mm_idx_destroy(mi);
 	}
+	n_parts = idx_rdr->n_parts;
 	mm_idx_reader_close(idx_rdr);
 
+	if (opt.split_prefix)
+		mm_split_merge(argc - (optind + 1), (const char**)&argv[optind + 1], &opt, n_parts);
+
 	if (fflush(stdout) == EOF) {
 		fprintf(stderr, "[ERROR] failed to write the results\n");
 		exit(EXIT_FAILURE);

map.c

@@ -11,6 +11,7 @@
 
 struct mm_tbuf_s {
 	void *km;
+	int rep_len, frag_gap;
 };
 
 mm_tbuf_t *mm_tbuf_init(void)
@@ -330,6 +331,8 @@ void mm_map_frag(const mm_idx_t *mi, int n_segs, const int *qlens, const char **
 			a = mm_chain_dp(max_chain_gap_ref, max_chain_gap_qry, opt->bw, opt->max_chain_skip, opt->min_cnt, opt->min_chain_score, is_splice, n_segs, n_a, a, &n_regs0, &u, b->km);
 		}
 	}
+	b->frag_gap = max_chain_gap_ref;
+	b->rep_len = rep_len;
 
 	regs0 = mm_gen_regs(b->km, hash, qlen_sum, n_regs0, u, a);
 
@@ -394,13 +397,17 @@ typedef struct {
 	mm_bseq_file_t **fp;
 	const mm_idx_t *mi;
 	kstring_t str;
+
+	int n_parts;
+	uint32_t *rid_shift;
+	FILE *fp_split, **fp_parts;
 } pipeline_t;
 
 typedef struct {
 	const pipeline_t *p;
     int n_seq, n_frag;
 	mm_bseq1_t *seq;
-	int *n_reg, *seg_off, *n_seg;
+	int *n_reg, *seg_off, *n_seg, *rep_len, *frag_gap;
 	mm_reg1_t **reg;
 	mm_tbuf_t **buf;
 } step_t;
@@ -421,10 +428,17 @@ static void worker_for(void *_data, long i, int tid) // kt_for() callback
 		qseqs[j] = s->seq[off + j].seq;
 	}
 	if (s->p->opt->flag & MM_F_INDEPEND_SEG) {
-		for (j = 0; j < s->n_seg[i]; ++j)
+		for (j = 0; j < s->n_seg[i]; ++j) {
 			mm_map_frag(s->p->mi, 1, &qlens[j], &qseqs[j], &s->n_reg[off+j], &s->reg[off+j], b, s->p->opt, s->seq[off+j].name);
+			s->rep_len[off + j] = b->rep_len;
+			s->frag_gap[off + j] = b->frag_gap;
+		}
 	} else {
 		mm_map_frag(s->p->mi, s->n_seg[i], qlens, qseqs, &s->n_reg[off], &s->reg[off], b, s->p->opt, s->seq[off].name);
+		for (j = 0; j < s->n_seg[i]; ++j) {
+			s->rep_len[off + j] = b->rep_len;
+			s->frag_gap[off + j] = b->frag_gap;
+		}
 	}
 	for (j = 0; j < s->n_seg[i]; ++j) // flip the query strand and coordinate to the original read strand
 		if (s->n_seg[i] == 2 && ((j == 0 && (pe_ori>>1&1)) || (j == 1 && (pe_ori&1)))) {
@@ -440,6 +454,63 @@ static void worker_for(void *_data, long i, int tid) // kt_for() callback
 		}
 }
 
+static void merge_hits(step_t *s)
+{
+	int f, i, k0, k, max_seg = 0, *n_reg_part, *rep_len_part, *frag_gap_part, *qlens;
+	void *km;
+	FILE **fp = s->p->fp_parts;
+	const mm_mapopt_t *opt = s->p->opt;
+
+	km = km_init();
+	for (f = 0; f < s->n_frag; ++f)
+		max_seg = max_seg > s->n_seg[f]? max_seg : s->n_seg[f];
+	qlens = CALLOC(int, max_seg + s->p->n_parts * 3);
+	n_reg_part = qlens + max_seg;
+	rep_len_part = n_reg_part + s->p->n_parts;
+	frag_gap_part = rep_len_part + s->p->n_parts;
+	for (f = 0, k = k0 = 0; f < s->n_frag; ++f) {
+		k0 = k;
+		for (i = 0; i < s->n_seg[f]; ++i, ++k) {
+			int j, l, t, rep_len = 0;
+			qlens[i] = s->seq[k].l_seq;
+			for (j = 0, s->n_reg[k] = 0; j < s->p->n_parts; ++j) {
+				mm_err_fread(&n_reg_part[j],    sizeof(int), 1, fp[j]);
+				mm_err_fread(&rep_len_part[j],  sizeof(int), 1, fp[j]);
+				mm_err_fread(&frag_gap_part[j], sizeof(int), 1, fp[j]);
+				s->n_reg[k] += n_reg_part[j];
+				if (rep_len < rep_len_part[j])
+					rep_len = rep_len_part[j];
+			}
+			s->reg[k] = CALLOC(mm_reg1_t, s->n_reg[k]);
+			for (j = 0, l = 0; j < s->p->n_parts; ++j) {
+				for (t = 0; t < n_reg_part[j]; ++t, ++l) {
+					mm_reg1_t *r = &s->reg[k][l];
+					uint32_t capacity;
+					mm_err_fread(r, sizeof(mm_reg1_t), 1, fp[j]);
+					r->rid += s->p->rid_shift[j];
+					if (opt->flag & MM_F_CIGAR) {
+						mm_err_fread(&capacity, 4, 1, fp[j]);
+						r->p = (mm_extra_t*)calloc(capacity, 4);
+						r->p->capacity = capacity;
+						mm_err_fread(r->p, r->p->capacity, 4, fp[j]);
+					}
+				}
+			}
+			mm_hit_sort(km, &s->n_reg[k], s->reg[k]);
+			mm_set_parent(km, opt->mask_level, s->n_reg[k], s->reg[k], opt->a * 2 + opt->b);
+			if (!(opt->flag & MM_F_ALL_CHAINS)) {
+				mm_select_sub(km, opt->pri_ratio, s->p->mi->k*2, opt->best_n, &s->n_reg[k], s->reg[k]);
+				mm_set_sam_pri(s->n_reg[k], s->reg[k]);
+			}
+			mm_set_mapq(km, s->n_reg[k], s->reg[k], opt->min_chain_score, opt->a, rep_len, !!(opt->flag & MM_F_SR));
+		}
+		if (s->n_seg[f] == 2 && opt->pe_ori >= 0 && (opt->flag&MM_F_CIGAR))
+			mm_pair(km, frag_gap_part[0], opt->pe_bonus, opt->a * 2 + opt->b, opt->a, qlens, &s->n_reg[k0], &s->reg[k0]);
+	}
+	free(qlens);
+	km_destroy(km);
+}
+
 static void *worker_pipeline(void *shared, int step, void *in)
 {
 	int i, j, k;
@@ -459,9 +530,11 @@ static void *worker_pipeline(void *shared, int step, void *in)
 			s->buf = (mm_tbuf_t**)calloc(p->n_threads, sizeof(mm_tbuf_t*));
 			for (i = 0; i < p->n_threads; ++i)
 				s->buf[i] = mm_tbuf_init();
-			s->n_reg = (int*)calloc(3 * s->n_seq, sizeof(int));
+			s->n_reg = (int*)calloc(5 * s->n_seq, sizeof(int));
-			s->seg_off = s->n_reg + s->n_seq; // seg_off and n_seg are allocated together with n_reg
+			s->seg_off = s->n_reg + s->n_seq; // seg_off, n_seg, rep_len and frag_gap are allocated together with n_reg
 			s->n_seg = s->seg_off + s->n_seq;
+			s->rep_len = s->n_seg + s->n_seq;
+			s->frag_gap = s->rep_len + s->n_seq;
 			s->reg = (mm_reg1_t**)calloc(s->n_seq, sizeof(mm_reg1_t*));
 			for (i = 1, j = 0; i <= s->n_seq; ++i)
 				if (i == s->n_seq || !frag_mode || !mm_qname_same(s->seq[i-1].name, s->seq[i].name)) {
@@ -472,7 +545,8 @@ static void *worker_pipeline(void *shared, int step, void *in)
 			return s;
 		} else free(s);
     } else if (step == 1) { // step 1: map
-		kt_for(p->n_threads, worker_for, in, ((step_t*)in)->n_frag);
+		if (p->n_parts > 0) merge_hits((step_t*)in);
+		else kt_for(p->n_threads, worker_for, in, ((step_t*)in)->n_frag);
 		return in;
     } else if (step == 2) { // step 2: output
 		void *km = 0;
@@ -485,6 +559,19 @@ static void *worker_pipeline(void *shared, int step, void *in)
 			int seg_st = s->seg_off[k], seg_en = s->seg_off[k] + s->n_seg[k];
 			for (i = seg_st; i < seg_en; ++i) {
 				mm_bseq1_t *t = &s->seq[i];
+				if (p->opt->split_prefix && p->n_parts == 0) { // then write to temporary files
+					mm_err_fwrite(&s->n_reg[i],    sizeof(int), 1, p->fp_split);
+					mm_err_fwrite(&s->rep_len[i],  sizeof(int), 1, p->fp_split);
+					mm_err_fwrite(&s->frag_gap[i], sizeof(int), 1, p->fp_split);
+					for (j = 0; j < s->n_reg[i]; ++j) {
+						mm_reg1_t *r = &s->reg[i][j];
+						mm_err_fwrite(r, sizeof(mm_reg1_t), 1, p->fp_split);
+						if (p->opt->flag & MM_F_CIGAR) {
+							mm_err_fwrite(&r->p->capacity, 4, 1, p->fp_split);
+							mm_err_fwrite(r->p, r->p->capacity, 4, p->fp_split);
+						}
+					}
+				} else if (s->n_reg[i] > 0) { // the query has at least one hit
 					for (j = 0; j < s->n_reg[i]; ++j) {
 						mm_reg1_t *r = &s->reg[i][j];
 						assert(!r->sam_pri || r->id == r->parent);
@@ -496,16 +583,14 @@ static void *worker_pipeline(void *shared, int step, void *in)
 							mm_write_paf(&p->str, mi, t, r, km, p->opt->flag);
 						mm_err_puts(p->str.s);
 					}
-				if (s->n_reg[i] == 0) {
+				} else if (p->opt->flag & (MM_F_OUT_SAM|MM_F_PAF_NO_HIT)) { // output an empty hit, if requested
-					if (p->opt->flag & MM_F_OUT_SAM) {
+					if (p->opt->flag & MM_F_OUT_SAM)
 						mm_write_sam2(&p->str, mi, t, i - seg_st, -1, s->n_seg[k], &s->n_reg[seg_st], (const mm_reg1_t*const*)&s->reg[seg_st], km, p->opt->flag);
-						mm_err_puts(p->str.s);
+					else
-					} else if (p->opt->flag & MM_F_PAF_NO_HIT) {
 						mm_write_paf(&p->str, mi, t, 0, 0, p->opt->flag);
 					mm_err_puts(p->str.s);
 				}
 			}
-			}
 			for (i = seg_st; i < seg_en; ++i) {
 				for (j = 0; j < s->n_reg[i]; ++j) free(s->reg[i][j].p);
 				free(s->reg[i]);
@@ -513,7 +598,7 @@ static void *worker_pipeline(void *shared, int step, void *in)
 				if (s->seq[i].qual) free(s->seq[i].qual);
 			}
 		}
-		free(s->reg); free(s->n_reg); free(s->seq); // seg_off and n_seg were allocated with reg; no memory leak here
+		free(s->reg); free(s->n_reg); free(s->seq); // seg_off, n_seg, rep_len and frag_gap were allocated with reg; no memory leak here
 		km_destroy(km);
 		if (mm_verbose >= 3)
 			fprintf(stderr, "[M::%s::%.3f*%.2f] mapped %d sequences\n", __func__, realtime() - mm_realtime0, cputime() / (realtime() - mm_realtime0), s->n_seq);
@@ -522,32 +607,44 @@ static void *worker_pipeline(void *shared, int step, void *in)
     return 0;
 }
 
+static mm_bseq_file_t **open_bseqs(int n, const char **fn)
+{
+	mm_bseq_file_t **fp;
+	int i, j;
+	fp = (mm_bseq_file_t**)calloc(n, sizeof(mm_bseq_file_t*));
+	for (i = 0; i < n; ++i) {
+		if ((fp[i] = mm_bseq_open(fn[i])) == 0) {
+			if (mm_verbose >= 1)
+				fprintf(stderr, "ERROR: failed to open file '%s'\n", fn[i]);
+			for (j = 0; j < i; ++j)
+				mm_bseq_close(fp[j]);
+			free(fp);
+			return 0;
+		}
+	}
+	return fp;
+}
+
 int mm_map_file_frag(const mm_idx_t *idx, int n_segs, const char **fn, const mm_mapopt_t *opt, int n_threads)
 {
-	int i, j, pl_threads;
+	int i, pl_threads;
 	pipeline_t pl;
 	if (n_segs < 1) return -1;
 	memset(&pl, 0, sizeof(pipeline_t));
 	pl.n_fp = n_segs;
-	pl.fp = (mm_bseq_file_t**)calloc(n_segs, sizeof(mm_bseq_file_t*));
+	pl.fp = open_bseqs(pl.n_fp, fn);
-	for (i = 0; i < n_segs; ++i) {
+	if (pl.fp == 0) return -1;
-		pl.fp[i] = mm_bseq_open(fn[i]);
-		if (pl.fp[i] == 0) {
-			if (mm_verbose >= 1)
-				fprintf(stderr, "ERROR: failed to open file '%s'\n", fn[i]);
-			for (j = 0; j < i; ++j)
-				mm_bseq_close(pl.fp[j]);
-			free(pl.fp);
-			return -1;
-		}
-	}
 	pl.opt = opt, pl.mi = idx;
 	pl.n_threads = n_threads > 1? n_threads : 1;
 	pl.mini_batch_size = opt->mini_batch_size;
+	if (opt->split_prefix)
+		pl.fp_split = mm_split_init(opt->split_prefix, idx);
 	pl_threads = n_threads == 1? 1 : (opt->flag&MM_F_2_IO_THREADS)? 3 : 2;
 	kt_pipeline(pl_threads, worker_pipeline, &pl, 3);
+
 	free(pl.str.s);
-	for (i = 0; i < n_segs; ++i)
+	if (pl.fp_split) fclose(pl.fp_split);
+	for (i = 0; i < pl.n_fp; ++i)
 		mm_bseq_close(pl.fp[i]);
 	free(pl.fp);
 	return 0;
@@ -557,3 +654,48 @@ int mm_map_file(const mm_idx_t *idx, const char *fn, const mm_mapopt_t *opt, int
 {
 	return mm_map_file_frag(idx, 1, &fn, opt, n_threads);
 }
+
+int mm_split_merge(int n_segs, const char **fn, const mm_mapopt_t *opt, int n_split_idx)
+{
+	int i;
+	pipeline_t pl;
+	mm_idx_t *mi;
+	if (n_segs < 1 || n_split_idx < 1) return -1;
+	memset(&pl, 0, sizeof(pipeline_t));
+	pl.n_fp = n_segs;
+	pl.fp = open_bseqs(pl.n_fp, fn);
+	if (pl.fp == 0) return -1;
+	pl.opt = opt;
+	pl.mini_batch_size = opt->mini_batch_size;
+
+	pl.n_parts = n_split_idx;
+	pl.fp_parts  = CALLOC(FILE*, pl.n_parts);
+	pl.rid_shift = CALLOC(uint32_t, pl.n_parts);
+	pl.mi = mi = mm_split_merge_prep(opt->split_prefix, n_split_idx, pl.fp_parts, pl.rid_shift);
+	if (pl.mi == 0) {
+		free(pl.fp_parts);
+		free(pl.rid_shift);
+		return -1;
+	}
+	for (i = n_split_idx - 1; i > 0; --i)
+		pl.rid_shift[i] = pl.rid_shift[i - 1];
+	for (pl.rid_shift[0] = 0, i = 1; i < n_split_idx; ++i)
+		pl.rid_shift[i] += pl.rid_shift[i - 1];
+	if (opt->flag & MM_F_OUT_SAM)
+		for (i = 0; i < pl.mi->n_seq; ++i)
+			printf("@SQ\tSN:%s\tLN:%d\n", pl.mi->seq[i].name, pl.mi->seq[i].len);
+
+	kt_pipeline(2, worker_pipeline, &pl, 3);
+
+	free(pl.str.s);
+	mm_idx_destroy(mi);
+	free(pl.rid_shift);
+	for (i = 0; i < n_split_idx; ++i)
+		fclose(pl.fp_parts[i]);
+	free(pl.fp_parts);
+	for (i = 0; i < pl.n_fp; ++i)
+		mm_bseq_close(pl.fp[i]);
+	free(pl.fp);
+	mm_split_rm_tmp(opt->split_prefix, n_split_idx);
+	return 0;
+}

minimap.h

@@ -60,6 +60,7 @@ typedef struct {
 typedef struct {
 	int32_t b, w, k, flag;
 	uint32_t n_seq;            // number of reference sequences
+	int32_t index;
 	mm_idx_seq_t *seq;         // sequence name, length and offset
 	uint32_t *S;               // 4-bit packed sequence
 	struct mm_idx_bucket_s *B; // index (hidden)
@@ -136,6 +137,8 @@ typedef struct {
 	int32_t mid_occ;     // ignore seeds with occurrences above this threshold
 	int32_t max_occ;
 	int mini_batch_size; // size of a batch of query bases to process in parallel
+
+	const char *split_prefix;
 } mm_mapopt_t;
 
 // index reader

minimap2.1

@@ -239,7 +239,7 @@ Disable the long gap patching heuristic. When this option is applied, the
 maximum alignment gap is mostly controlled by
 .BR -r .
 .TP
-.B --lj-min-ratio \ FLOAT
+.BI --lj-min-ratio \ FLOAT
 Fraction of query sequence length required to bridge a long gap [0.5]. A
 smaller value helps to recover longer gaps, at the cost of more false gaps.
 .TP
@@ -252,6 +252,9 @@ applies a second round of chaining with a higher minimizer occurrence threshold
 if no good chain is found. In addition, minimap2 attempts to patch gaps between
 seeds with ungapped alignment.
 .TP
+.BI --split-prefix \ STR
+Prefix to create temporary files. Typically used for a multi-part index.
+.TP
 .BR --frag = no | yes
 Whether to enable the fragment mode [no]
 .TP

misc.c

@@ -131,6 +131,26 @@ void mm_err_puts(const char *str)
 	}
 }
 
+void mm_err_fwrite(const void *p, size_t size, size_t nitems, FILE *fp)
+{
+	int ret;
+	ret = fwrite(p, size, nitems, fp);
+	if (ret == EOF) {
+		fprintf(stderr, "[ERROR] failed to write data\n");
+		exit(EXIT_FAILURE);
+	}
+}
+
+void mm_err_fread(void *p, size_t size, size_t nitems, FILE *fp)
+{
+	int ret;
+	ret = fread(p, size, nitems, fp);
+	if (ret == EOF) {
+		fprintf(stderr, "[ERROR] failed to read data\n");
+		exit(EXIT_FAILURE);
+	}
+}
+
 #include "ksort.h"
 
 #define sort_key_128x(a) ((a).x)

mmpriv.h

@@ -28,6 +28,9 @@
 #define mm_seq4_set(s, i, c) ((s)[(i)>>3] |= (uint32_t)(c) << (((i)&7)<<2))
 #define mm_seq4_get(s, i)    ((s)[(i)>>3] >> (((i)&7)<<2) & 0xf)
 
+#define MALLOC(type, len) ((type*)malloc((len) * sizeof(type)))
+#define CALLOC(type, len) ((type*)calloc((len), sizeof(type)))
+
 #ifdef __cplusplus
 extern "C" {
 #endif
@@ -77,7 +80,7 @@ void mm_select_sub(void *km, float pri_ratio, int min_diff, int best_n, int *n_,
 void mm_select_sub_multi(void *km, float pri_ratio, float pri1, float pri2, int max_gap_ref, int min_diff, int best_n, int n_segs, const int *qlens, int *n_, mm_reg1_t *r);
 void mm_filter_regs(const mm_mapopt_t *opt, int qlen, int *n_regs, mm_reg1_t *regs);
 void mm_join_long(void *km, const mm_mapopt_t *opt, int qlen, int *n_regs, mm_reg1_t *regs, mm128_t *a);
-void mm_hit_sort_by_dp(void *km, int *n_regs, mm_reg1_t *r);
+void mm_hit_sort(void *km, int *n_regs, mm_reg1_t *r);
 void mm_set_mapq(void *km, int n_regs, mm_reg1_t *regs, int min_chain_sc, int match_sc, int rep_len, int is_sr);
 
 void mm_est_err(const mm_idx_t *mi, int qlen, int n_regs, mm_reg1_t *regs, const mm128_t *a, int32_t n, const uint64_t *mini_pos);
@@ -86,7 +89,14 @@ mm_seg_t *mm_seg_gen(void *km, uint32_t hash, int n_segs, const int *qlens, int
 void mm_seg_free(void *km, int n_segs, mm_seg_t *segs);
 void mm_pair(void *km, int max_gap_ref, int dp_bonus, int sub_diff, int match_sc, const int *qlens, int *n_regs, mm_reg1_t **regs);
 
+FILE *mm_split_init(const char *prefix, const mm_idx_t *mi);
+mm_idx_t *mm_split_merge_prep(const char *prefix, int n_splits, FILE **fp, uint32_t *n_seq_part);
+int mm_split_merge(int n_segs, const char **fn, const mm_mapopt_t *opt, int n_split_idx);
+void mm_split_rm_tmp(const char *prefix, int n_splits);
+
 void mm_err_puts(const char *str);
+void mm_err_fwrite(const void *p, size_t size, size_t nitems, FILE *fp);
+void mm_err_fread(void *p, size_t size, size_t nitems, FILE *fp);
 
 #ifdef __cplusplus
 }

splitidx.c

@@ -0,0 +1,80 @@
+#include <string.h>
+#include <assert.h>
+#include <stdlib.h>
+#include <stdio.h>
+#include "mmpriv.h"
+
+FILE *mm_split_init(const char *prefix, const mm_idx_t *mi)
+{
+	char *fn;
+	FILE *fp;
+	uint32_t i, k = mi->k;
+	fn = (char*)calloc(strlen(prefix) + 10, 1);
+	sprintf(fn, "%s.%.4d.tmp", prefix, mi->index);
+	fp = fopen(fn, "wb");
+	assert(fp);
+	mm_err_fwrite(&k, 4, 1, fp);
+	mm_err_fwrite(&mi->n_seq, 4, 1, fp);
+	for (i = 0; i < mi->n_seq; ++i) {
+		uint8_t l;
+		l = strlen(mi->seq[i].name);
+		mm_err_fwrite(&l, 1, 1, fp);
+		mm_err_fwrite(mi->seq[i].name, 1, l, fp);
+		mm_err_fwrite(&mi->seq[i].len, 4, 1, fp);
+	}
+	free(fn);
+	return fp;
+}
+
+mm_idx_t *mm_split_merge_prep(const char *prefix, int n_splits, FILE **fp, uint32_t *n_seq_part)
+{
+	mm_idx_t *mi = 0;
+	char *fn;
+	int i, j;
+
+	if (n_splits < 1) return 0;
+	fn = CALLOC(char, strlen(prefix) + 10);
+	for (i = 0; i < n_splits; ++i) {
+		sprintf(fn, "%s.%.4d.tmp", prefix, i);
+		if ((fp[i] = fopen(fn, "rb")) == 0) {
+			if (mm_verbose >= 1)
+				fprintf(stderr, "ERROR: failed to open temporary file '%s'\n", fn);
+			for (j = 0; j < i; ++j)
+				fclose(fp[j]);
+			free(fn);
+			return 0;
+		}
+	}
+	free(fn);
+
+	mi = CALLOC(mm_idx_t, 1);
+	for (i = 0; i < n_splits; ++i) {
+		mm_err_fread(&mi->k, 4, 1, fp[i]); // TODO: check if k is all the same
+		mm_err_fread(&n_seq_part[i], 4, 1, fp[i]);
+		mi->n_seq += n_seq_part[i];
+	}
+	mi->seq = CALLOC(mm_idx_seq_t, mi->n_seq);
+	for (i = j = 0; i < n_splits; ++i) {
+		uint32_t k;
+		for (k = 0; k < n_seq_part[i]; ++k, ++j) {
+			uint8_t l;
+			mm_err_fread(&l, 1, 1, fp[i]);
+			mi->seq[j].name = (char*)calloc(l + 1, 1);
+			mm_err_fread(mi->seq[j].name, 1, l, fp[i]);
+			mm_err_fread(&mi->seq[j].len, 4, 1, fp[i]);
+		}
+	}
+	return mi;
+}
+
+void mm_split_rm_tmp(const char *prefix, int n_splits)
+{
+	int i;
+	char *fn;
+	fn = CALLOC(char, strlen(prefix) + 10);
+	for (i = 0; i < n_splits; ++i) {
+		sprintf(fn, "%s.%.4d.tmp", prefix, i);
+		remove(fn);
+	}
+	free(fn);
+}