+static void *worker(void *data)
+{
+ worker_t *w = (worker_t*)data;
+ char *name;
+ ks_mergesort(sort, w->buf_len, w->buf, 0);
+ name = (char*)calloc(strlen(w->prefix) + 20, 1);
+ sprintf(name, "%s.%.4d.bam", w->prefix, w->index);
+ write_buffer(name, "w1", w->buf_len, w->buf, w->h, 0);
+ free(name);
+ return 0;
+}
+
+static int sort_blocks(int n_files, size_t k, bam1_p *buf, const char *prefix, const bam_header_t *h, int n_threads)
+{
+ int i;
+ size_t rest;
+ bam1_p *b;
+ pthread_t *tid;
+ pthread_attr_t attr;
+ worker_t *w;
+
+ if (n_threads < 1) n_threads = 1;
+ if (k < n_threads * 64) n_threads = 1; // use a single thread if we only sort a small batch of records
+ pthread_attr_init(&attr);
+ pthread_attr_setdetachstate(&attr, PTHREAD_CREATE_JOINABLE);
+ w = calloc(n_threads, sizeof(worker_t));
+ tid = calloc(n_threads, sizeof(pthread_t));
+ b = buf; rest = k;
+ for (i = 0; i < n_threads; ++i) {
+ w[i].buf_len = rest / (n_threads - i);
+ w[i].buf = b;
+ w[i].prefix = prefix;
+ w[i].h = h;
+ w[i].index = n_files + i;
+ b += w[i].buf_len; rest -= w[i].buf_len;
+ pthread_create(&tid[i], &attr, worker, &w[i]);
+ }
+ for (i = 0; i < n_threads; ++i) pthread_join(tid[i], 0);
+ free(tid); free(w);
+ return n_files + n_threads;
+}
+
+/*!
+ @abstract Sort an unsorted BAM file based on the chromosome order
+ and the leftmost position of an alignment
+
+ @param is_by_qname whether to sort by query name
+ @param fn name of the file to be sorted
+ @param prefix prefix of the output and the temporary files; upon
+ sucessess, prefix.bam will be written.
+ @param max_mem approxiate maximum memory (very inaccurate)
+
+ @discussion It may create multiple temporary subalignment files
+ and then merge them by calling bam_merge_core(). This function is
+ NOT thread safe.
+ */
+void bam_sort_core_ext(int is_by_qname, const char *fn, const char *prefix, size_t _max_mem, int is_stdout, int n_threads, int level)