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* Elastic Binary Trees - macros and structures for operations on pointer nodes.
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* (C) 2002-2007 - Willy Tarreau <w@1wt.eu>
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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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* 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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* 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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#ifndef _COMMON_EBPTTREE_H
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#define _COMMON_EBPTTREE_H
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/* Return the structure of type <type> whose member <member> points to <ptr> */
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#define ebpt_entry(ptr, type, member) container_of(ptr, type, member)
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#define EBPT_ROOT EB_ROOT
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#define EBPT_TREE_HEAD EB_TREE_HEAD
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/* on *almost* all platforms, a pointer can be cast into a size_t which is unsigned */
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#define PTR_INT_TYPE size_t
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typedef PTR_INT_TYPE ptr_t;
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/* This structure carries a node, a leaf, and a key. It must start with the
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* eb_node so that it can be cast into an eb_node. We could also have put some
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* sort of transparent union here to reduce the indirection level, but the fact
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* is, the end user is not meant to manipulate internals, so this is pointless.
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struct eb_node node; /* the tree node, must be at the beginning */
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* Exported functions and macros.
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* Many of them are always inlined because they are extremely small, and
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* are generally called at most once or twice in a program.
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/* Return leftmost node in the tree, or NULL if none */
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static inline struct ebpt_node *ebpt_first(struct eb_root *root)
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return ebpt_entry(eb_first(root), struct ebpt_node, node);
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/* Return rightmost node in the tree, or NULL if none */
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static inline struct ebpt_node *ebpt_last(struct eb_root *root)
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return ebpt_entry(eb_last(root), struct ebpt_node, node);
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/* Return next node in the tree, or NULL if none */
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static inline struct ebpt_node *ebpt_next(struct ebpt_node *ebpt)
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return ebpt_entry(eb_next(&ebpt->node), struct ebpt_node, node);
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/* Return previous node in the tree, or NULL if none */
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static inline struct ebpt_node *ebpt_prev(struct ebpt_node *ebpt)
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return ebpt_entry(eb_prev(&ebpt->node), struct ebpt_node, node);
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/* Return next node in the tree, skipping duplicates, or NULL if none */
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static inline struct ebpt_node *ebpt_next_unique(struct ebpt_node *ebpt)
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return ebpt_entry(eb_next_unique(&ebpt->node), struct ebpt_node, node);
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/* Return previous node in the tree, skipping duplicates, or NULL if none */
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static inline struct ebpt_node *ebpt_prev_unique(struct ebpt_node *ebpt)
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return ebpt_entry(eb_prev_unique(&ebpt->node), struct ebpt_node, node);
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/* Delete node from the tree if it was linked in. Mark the node unused. Note
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* that this function relies on a non-inlined generic function: eb_delete.
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static inline void ebpt_delete(struct ebpt_node *ebpt)
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eb_delete(&ebpt->node);
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* The following functions are not inlined by default. They are declared
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* in ebpttree.c, which simply relies on their inline version.
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REGPRM2 struct ebpt_node *ebpt_lookup(struct eb_root *root, void *x);
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REGPRM2 struct ebpt_node *ebpt_insert(struct eb_root *root, struct ebpt_node *new);
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* The following functions are less likely to be used directly, because their
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* code is larger. The non-inlined version is preferred.
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/* Delete node from the tree if it was linked in. Mark the node unused. */
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static inline void __ebpt_delete(struct ebpt_node *ebpt)
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__eb_delete(&ebpt->node);
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* Find the first occurence of a key in the tree <root>. If none can be
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* found, return NULL.
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static inline struct ebpt_node *__ebpt_lookup(struct eb_root *root, void *x)
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struct ebpt_node *node;
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troot = root->b[EB_LEFT];
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if (unlikely(troot == NULL))
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if ((eb_gettag(troot) == EB_LEAF)) {
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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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node = container_of(eb_untag(troot, EB_NODE),
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struct ebpt_node, node.branches);
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if (x == node->key) {
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/* Either we found the node which holds the key, or
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* we have a dup tree. In the later case, we have to
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* walk it down left to get the first entry.
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if (node->node.bit < 0) {
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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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node = container_of(eb_untag(troot, EB_LEAF),
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struct ebpt_node, node.branches);
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troot = node->node.branches.b[((ptr_t)x >> node->node.bit) & EB_NODE_BRANCH_MASK];
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/* Insert ebpt_node <new> into subtree starting at node root <root>.
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* Only new->key needs be set with the key. The ebpt_node is returned.
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static inline struct ebpt_node *
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__ebpt_insert(struct eb_root *root, struct ebpt_node *new) {
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struct ebpt_node *old;
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void *newkey; /* caching the key saves approximately one cycle */
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troot = root->b[EB_LEFT];
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if (unlikely(troot == NULL)) {
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/* Tree is empty, insert the leaf part below the left branch */
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root->b[EB_LEFT] = eb_dotag(&new->node.branches, EB_LEAF);
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new->node.leaf_p = eb_dotag(root, EB_LEFT);
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new->node.node_p = NULL; /* node part unused */
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/* The tree descent is fairly easy :
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* - first, check if we have reached a leaf node
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* - second, check if we have gone too far
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* Everywhere, we use <new> for the node node we are inserting, <root>
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* for the node we attach it to, and <old> for the node we are
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* displacing below <new>. <troot> will always point to the future node
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* (tagged with its type). <side> carries the side the node <new> is
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* attached to below its parent, which is also where previous node
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* was attached. <newkey> carries the key being inserted.
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if (unlikely(eb_gettag(troot) == EB_LEAF)) {
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eb_troot_t *new_left, *new_rght;
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eb_troot_t *new_leaf, *old_leaf;
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old = container_of(eb_untag(troot, EB_LEAF),
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struct ebpt_node, node.branches);
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new_left = eb_dotag(&new->node.branches, EB_LEFT);
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new_rght = eb_dotag(&new->node.branches, EB_RGHT);
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new_leaf = eb_dotag(&new->node.branches, EB_LEAF);
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old_leaf = eb_dotag(&old->node.branches, EB_LEAF);
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new->node.node_p = old->node.leaf_p;
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/* Right here, we have 3 possibilities :
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- the tree does not contain the key, and we have
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new->key < old->key. We insert new above old, on
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- the tree does not contain the key, and we have
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new->key > old->key. We insert new above old, on
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- the tree does contain the key, which implies it
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is alone. We add the new key next to it as a
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The last two cases can easily be partially merged.
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if (new->key < old->key) {
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new->node.leaf_p = new_left;
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old->node.leaf_p = new_rght;
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new->node.branches.b[EB_LEFT] = new_leaf;
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new->node.branches.b[EB_RGHT] = old_leaf;
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/* new->key >= old->key, new goes the right */
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old->node.leaf_p = new_left;
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new->node.leaf_p = new_rght;
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new->node.branches.b[EB_LEFT] = old_leaf;
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new->node.branches.b[EB_RGHT] = new_leaf;
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if (new->key == old->key) {
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root->b[side] = eb_dotag(&new->node.branches, EB_NODE);
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/* OK we're walking down this link */
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old = container_of(eb_untag(troot, EB_NODE),
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struct ebpt_node, node.branches);
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/* Stop going down when we don't have common bits anymore. We
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* also stop in front of a duplicates tree because it means we
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* have to insert above.
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if ((old->node.bit < 0) || /* we're above a duplicate tree, stop here */
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((((ptr_t)new->key ^ (ptr_t)old->key) >> old->node.bit) >= EB_NODE_BRANCHES)) {
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/* The tree did not contain the key, so we insert <new> before the node
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* <old>, and set ->bit to designate the lowest bit position in <new>
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* which applies to ->branches.b[].
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eb_troot_t *new_left, *new_rght;
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eb_troot_t *new_leaf, *old_node;
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new_left = eb_dotag(&new->node.branches, EB_LEFT);
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new_rght = eb_dotag(&new->node.branches, EB_RGHT);
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new_leaf = eb_dotag(&new->node.branches, EB_LEAF);
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old_node = eb_dotag(&old->node.branches, EB_NODE);
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new->node.node_p = old->node.node_p;
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if (new->key < old->key) {
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new->node.leaf_p = new_left;
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old->node.node_p = new_rght;
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new->node.branches.b[EB_LEFT] = new_leaf;
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new->node.branches.b[EB_RGHT] = old_node;
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else if (new->key > old->key) {
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old->node.node_p = new_left;
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new->node.leaf_p = new_rght;
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new->node.branches.b[EB_LEFT] = old_node;
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new->node.branches.b[EB_RGHT] = new_leaf;
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ret = eb_insert_dup(&old->node, &new->node);
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return container_of(ret, struct ebpt_node, node);
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root = &old->node.branches;
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side = ((ptr_t)newkey >> old->node.bit) & EB_NODE_BRANCH_MASK;
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troot = root->b[side];
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/* Ok, now we are inserting <new> between <root> and <old>. <old>'s
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* parent is already set to <new>, and the <root>'s branch is still in
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* <side>. Update the root's leaf till we have it. Note that we can also
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* find the side by checking the side of new->node.node_p.
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/* We need the common higher bits between new->key and old->key.
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* What differences are there between new->key and the node here ?
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* NOTE that bit(new) is always < bit(root) because highest
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* bit of new->key and old->key are identical here (otherwise they
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* would sit on different branches).
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// note that if EB_NODE_BITS > 1, we should check that it's still >= 0
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/* let the compiler choose the best branch based on the pointer size */
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if (sizeof(ptr_t) == 4)
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new->node.bit = flsnz((ptr_t)new->key ^ (ptr_t)old->key) - EB_NODE_BITS;
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new->node.bit = fls64((ptr_t)new->key ^ (ptr_t)old->key) - EB_NODE_BITS;
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root->b[side] = eb_dotag(&new->node.branches, EB_NODE);
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#endif /* _COMMON_EBPTTREE_H */
added
removed
include/common/ebpttree.h
