-void btr_add_output_pool(struct btr_pool *btrp, char *buf, size_t size,
+void btr_add_output_pool(struct btr_pool *btrp, size_t size,
+ struct btr_node *btrn);
+size_t btr_pool_unused(struct btr_pool *btrp);
+void btr_copy(const void *src, size_t n, struct btr_pool *btrp,