+
+void *btr_context(struct btr_node *btrn)
+{
+ return btrn->context;
+}
+
+/**
+ * Merge the first two input buffers into one.
+ *
+ * This is a quite expensive operation.
+ *
+ * \return The number of buffers that have been available (zero, one or two).
+ */
+int btr_merge(struct btr_node *btrn)
+{
+ struct btr_buffer_reference *brs[2], *br;
+ char *bufs[2], *buf;
+ size_t szs[2], sz;
+ int i;
+
+ if (list_empty(&btrn->input_queue))
+ return 0;
+ if (list_is_singular(&btrn->input_queue))
+ return 1;
+ i = 0;
+ /* get references to the first two buffers */
+ FOR_EACH_BUFFER_REF(br, btrn) {
+ brs[i] = br;
+ szs[i] = btr_get_buffer_by_reference(brs[i], bufs + i);
+ i++;
+ if (i == 2)
+ break;
+ }
+ /* make a new btrb that combines the two buffers and a br to it. */
+ sz = szs[0] + szs[1];
+ //PARA_CRIT_LOG("merging input buffers: (%zu, %zu) -> %zu\n",
+ // szs[0], szs[1], sz);
+ buf = para_malloc(sz);
+ /* TODO: Avoid this memcopy by introducing btr buffer pool. */
+ memcpy(buf, bufs[0], szs[0]);
+ memcpy(buf + szs[0], bufs[1], szs[1]);
+
+ br = para_malloc(sizeof(*br));
+ br->btrb = new_btrb(buf, sz);
+ br->btrb->refcount = 1;
+ br->consumed = 0;
+
+ /* replace the first two refs by the new one */
+ btr_drop_buffer_reference(brs[0]);
+ btr_drop_buffer_reference(brs[1]);
+ para_list_add(&br->node, &btrn->input_queue);
+ return 2;
+}
+
+void btr_merge_to(struct btr_node *btrn, size_t dest_size)
+{
+ for (;;) {
+ char *buf;
+ size_t len = btr_next_buffer(btrn, &buf);
+ if (len >= dest_size)
+ return;
+ if (btr_merge(btrn) < 2)
+ return;
+ }
+}