Function rn_inithead_internal

freebsd/net/radix.c:1090–1106

* Initialize an empty tree. This has 3 nodes, which are passed * via base_nodes (in the order ) and are * marked RNF_ROOT so they cannot be freed. * The leaves have all-zero and all-one keys, with significant * bits starting at 'off'. */

 * bits starting at 'off'.
 */
void
rn_inithead_internal(struct radix_head *rh, struct radix_node *base_nodes, int off)
{
	struct radix_node *t, *tt, *ttt;

	t = rn_newpair(rn_zeros, off, base_nodes);
	ttt = base_nodes + 2;
	t->rn_right = ttt;
	t->rn_parent = t;
	tt = t->rn_left;	/* ... which in turn is base_nodes */
	tt->rn_flags = t->rn_flags = RNF_ROOT | RNF_ACTIVE;
	tt->rn_bit = -1 - off;
	*ttt = *tt;
	ttt->rn_key = rn_ones;

	rh->rnh_treetop = t;
}

static void
rn_detachhead_internal(struct radix_head *head)