tree_desc
static void gen_bitlen (deflate_state *s, tree_desc *desc);
static void build_tree (deflate_state *s, tree_desc *desc);
tree_desc *desc /* the tree descriptor */
tree_desc *desc /* the tree descriptor */
gen_bitlen(s, (tree_desc *)desc);
build_tree(s, (tree_desc *)(&(s->bl_desc)));
build_tree(s, (tree_desc *)(&(s->l_desc)));
build_tree(s, (tree_desc *)(&(s->d_desc)));