208 lines
6.8 KiB
C
208 lines
6.8 KiB
C
/*
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* Elastic Binary Trees - exported functions for operations on pointer nodes.
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* (C) 2002-2007 - Willy Tarreau <w@1wt.eu>
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
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*/
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/* Consult ebpttree.h for more details about those functions */
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#include "ebpttree.h"
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REGPRM2 struct ebpt_node *ebpt_insert(struct eb_root *root, struct ebpt_node *new)
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{
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return __ebpt_insert(root, new);
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}
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REGPRM2 struct ebpt_node *ebpt_lookup(struct eb_root *root, void *x)
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{
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return __ebpt_lookup(root, x);
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}
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/*
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* Find the last occurrence of the highest key in the tree <root>, which is
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* equal to or less than <x>. NULL is returned is no key matches.
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*/
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REGPRM2 struct ebpt_node *ebpt_lookup_le(struct eb_root *root, void *x)
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{
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struct ebpt_node *node;
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eb_troot_t *troot;
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troot = root->b[EB_LEFT];
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if (unlikely(troot == NULL))
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return NULL;
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while (1) {
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if ((eb_gettag(troot) == EB_LEAF)) {
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/* We reached a leaf, which means that the whole upper
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* parts were common. We will return either the current
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* node or its next one if the former is too small.
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*/
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node = container_of(eb_untag(troot, EB_LEAF),
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struct ebpt_node, node.branches);
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if (node->key <= x)
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return node;
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/* return prev */
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troot = node->node.leaf_p;
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break;
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}
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node = container_of(eb_untag(troot, EB_NODE),
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struct ebpt_node, node.branches);
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if (node->node.bit < 0) {
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/* We're at the top of a dup tree. Either we got a
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* matching value and we return the rightmost node, or
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* we don't and we skip the whole subtree to return the
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* prev node before the subtree. Note that since we're
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* at the top of the dup tree, we can simply return the
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* prev node without first trying to escape from the
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* tree.
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*/
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if (node->key <= x) {
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troot = node->node.branches.b[EB_RGHT];
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while (eb_gettag(troot) != EB_LEAF)
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troot = (eb_untag(troot, EB_NODE))->b[EB_RGHT];
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return container_of(eb_untag(troot, EB_LEAF),
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struct ebpt_node, node.branches);
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}
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/* return prev */
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troot = node->node.node_p;
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break;
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}
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if ((((ptr_t)x ^ (ptr_t)node->key) >> node->node.bit) >= EB_NODE_BRANCHES) {
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/* No more common bits at all. Either this node is too
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* small and we need to get its highest value, or it is
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* too large, and we need to get the prev value.
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*/
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if (((ptr_t)node->key >> node->node.bit) > ((ptr_t)x >> node->node.bit)) {
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troot = node->node.branches.b[EB_RGHT];
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return ebpt_entry(eb_walk_down(troot, EB_RGHT), struct ebpt_node, node);
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}
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/* Further values will be too high here, so return the prev
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* unique node (if it exists).
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*/
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troot = node->node.node_p;
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break;
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}
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troot = node->node.branches.b[((ptr_t)x >> node->node.bit) & EB_NODE_BRANCH_MASK];
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}
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/* If we get here, it means we want to report previous node before the
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* current one which is not above. <troot> is already initialised to
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* the parent's branches.
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*/
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while (eb_gettag(troot) == EB_LEFT) {
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/* Walking up from left branch. We must ensure that we never
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* walk beyond root.
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*/
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if (unlikely(eb_clrtag((eb_untag(troot, EB_LEFT))->b[EB_RGHT]) == NULL))
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return NULL;
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troot = (eb_root_to_node(eb_untag(troot, EB_LEFT)))->node_p;
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}
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/* Note that <troot> cannot be NULL at this stage */
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troot = (eb_untag(troot, EB_RGHT))->b[EB_LEFT];
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node = ebpt_entry(eb_walk_down(troot, EB_RGHT), struct ebpt_node, node);
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return node;
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}
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/*
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* Find the first occurrence of the lowest key in the tree <root>, which is
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* equal to or greater than <x>. NULL is returned is no key matches.
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*/
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REGPRM2 struct ebpt_node *ebpt_lookup_ge(struct eb_root *root, void *x)
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{
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struct ebpt_node *node;
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eb_troot_t *troot;
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troot = root->b[EB_LEFT];
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if (unlikely(troot == NULL))
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return NULL;
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while (1) {
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if ((eb_gettag(troot) == EB_LEAF)) {
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/* We reached a leaf, which means that the whole upper
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* parts were common. We will return either the current
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* node or its next one if the former is too small.
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*/
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node = container_of(eb_untag(troot, EB_LEAF),
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struct ebpt_node, node.branches);
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if (node->key >= x)
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return node;
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/* return next */
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troot = node->node.leaf_p;
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break;
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}
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node = container_of(eb_untag(troot, EB_NODE),
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struct ebpt_node, node.branches);
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if (node->node.bit < 0) {
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/* We're at the top of a dup tree. Either we got a
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* matching value and we return the leftmost node, or
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* we don't and we skip the whole subtree to return the
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* next node after the subtree. Note that since we're
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* at the top of the dup tree, we can simply return the
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* next node without first trying to escape from the
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* tree.
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*/
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if (node->key >= x) {
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troot = node->node.branches.b[EB_LEFT];
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while (eb_gettag(troot) != EB_LEAF)
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troot = (eb_untag(troot, EB_NODE))->b[EB_LEFT];
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return container_of(eb_untag(troot, EB_LEAF),
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struct ebpt_node, node.branches);
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}
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/* return next */
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troot = node->node.node_p;
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break;
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}
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if ((((ptr_t)x ^ (ptr_t)node->key) >> node->node.bit) >= EB_NODE_BRANCHES) {
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/* No more common bits at all. Either this node is too
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* large and we need to get its lowest value, or it is too
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* small, and we need to get the next value.
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*/
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if (((ptr_t)node->key >> node->node.bit) > ((ptr_t)x >> node->node.bit)) {
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troot = node->node.branches.b[EB_LEFT];
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return ebpt_entry(eb_walk_down(troot, EB_LEFT), struct ebpt_node, node);
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}
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/* Further values will be too low here, so return the next
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* unique node (if it exists).
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*/
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troot = node->node.node_p;
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break;
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}
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troot = node->node.branches.b[((ptr_t)x >> node->node.bit) & EB_NODE_BRANCH_MASK];
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}
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/* If we get here, it means we want to report next node after the
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* current one which is not below. <troot> is already initialised
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* to the parent's branches.
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*/
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while (eb_gettag(troot) != EB_LEFT)
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/* Walking up from right branch, so we cannot be below root */
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troot = (eb_root_to_node(eb_untag(troot, EB_RGHT)))->node_p;
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/* Note that <troot> cannot be NULL at this stage */
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troot = (eb_untag(troot, EB_LEFT))->b[EB_RGHT];
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if (eb_clrtag(troot) == NULL)
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return NULL;
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node = ebpt_entry(eb_walk_down(troot, EB_LEFT), struct ebpt_node, node);
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return node;
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}
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