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/* wmem_interval_tree.c
* Implements an augmented interval tree
* Based on the red-black tree implementation in epan/wmem.*
* Copyright 2015, Matthieu coudron <matthieu.coudron@lip6.fr>
*
* Wireshark - Network traffic analyzer
* By Gerald Combs <gerald@wireshark.org>
* Copyright 1998 Gerald Combs
*
* SPDX-License-Identifier: GPL-2.0-or-later
*/
#include "config.h"
#include <string.h>
#include <stdio.h>
#include <glib.h>
#include "wmem-int.h"
#include "wmem_core.h"
#include "wmem_tree-int.h"
#include "wmem_strutl.h"
#include "wmem_interval_tree.h"
#include "wmem_user_cb.h"
static void
print_range(const void *value)
{
const wmem_range_t *range = (const wmem_range_t *)value;
if(!value) {
return;
}
printf("Range: low=%" G_GUINT64_FORMAT " high=%" G_GUINT64_FORMAT " max_edge=%" G_GUINT64_FORMAT "\n", range->low, range->high, range->max_edge);
}
/**
* In an augmented interval tree, each node saves the maximum edge of its child subtrees
* This function compares the children max_edge with the current max_edge
* and propagates any change to the parent nodes.
*/
static void
update_max_edge(wmem_tree_node_t *node)
{
wmem_range_t *range;
const wmem_range_t *range_l;
const wmem_range_t *range_r;
guint64 maxEdge = 0;
if(!node) {
return ;
}
range = (wmem_range_t *)node->key;
range_l = (node->left) ? (const wmem_range_t *) (node->left->key) : NULL;
range_r = (node->right) ? (const wmem_range_t *) (node->right->key) : NULL;
maxEdge = range->high;
if(range_r) {
maxEdge = MAX(maxEdge, range_r->max_edge) ;
}
if(range_l) {
maxEdge = MAX(maxEdge, range_l->max_edge) ;
}
/* update the parent nodes only if a change happened (optimization) */
if(range->max_edge != maxEdge) {
range->max_edge = maxEdge;
update_max_edge(node->parent);
}
}
gboolean
wmem_itree_range_overlap(const wmem_range_t *r1, const wmem_range_t *r2)
{
return (r1->low <= r2->high && r2->low <= r1->high);
}
/* after a rotation, some of the children nodes might (dis)appear, thus we need
* to refresh children max_edge. Changes will propagate to parents */
static void update_edges_after_rotation(wmem_tree_node_t *node) {
if(node->left) update_max_edge(node->left);
if(node->right) update_max_edge(node->right);
}
wmem_itree_t *
wmem_itree_new(wmem_allocator_t *allocator)
{
wmem_itree_t *tree = wmem_tree_new(allocator);
tree->post_rotation_cb = &update_edges_after_rotation;
return tree;
}
gboolean
wmem_itree_is_empty(wmem_itree_t *tree)
{
return wmem_tree_is_empty(tree);
}
static int
wmem_tree_compare_ranges(const wmem_range_t *ra, const wmem_range_t *rb)
{
if( ra->low == rb->low) {
return 0;
}
else if(ra->low < rb->low) {
return -1;
}
else {
return 1;
}
}
void
wmem_itree_insert(wmem_itree_t *tree, const guint64 low, const guint64 high, void *data)
{
wmem_tree_node_t *node;
wmem_range_t *range = (wmem_range_t *)wmem_new(tree->data_allocator, wmem_range_t);
ASSERT(low <= high);
range->low = low;
range->high = high;
range->max_edge = 0;
node = wmem_tree_insert(tree, range, data, (compare_func)wmem_tree_compare_ranges);
/* in absence of rotation, we still need to update max_edge */
update_max_edge(node);
}
static void
wmem_itree_find_intervals_in_subtree(wmem_tree_node_t *node, wmem_range_t requested, wmem_list_t *results)
{
const wmem_range_t* current;
if(!node) {
return;
}
current = (wmem_range_t*)node->key;
/* there is no child that can possibly match */
if(requested.low > current->max_edge) {
return;
}
if(wmem_itree_range_overlap(current, &requested)) {
wmem_list_prepend(results, node->data);
}
wmem_itree_find_intervals_in_subtree(node->left, requested, results);
wmem_itree_find_intervals_in_subtree(node->right, requested, results);
}
wmem_list_t *
wmem_itree_find_intervals(wmem_itree_t *tree, wmem_allocator_t *allocator, guint64 low, guint64 high)
{
wmem_list_t *results = NULL;
wmem_range_t requested = { low, high, 0 };
results = wmem_list_new(allocator);
wmem_itree_find_intervals_in_subtree(tree->root, requested, results);
return results;
}
void
wmem_print_itree(wmem_tree_t *tree)
{
wmem_print_tree(tree, &print_range, NULL);
}
/*
* Editor modelines - https://www.wireshark.org/tools/modelines.html
*
* Local variables:
* c-basic-offset: 4
* tab-width: 8
* indent-tabs-mode: nil
* End:
*
* vi: set shiftwidth=4 tabstop=8 expandtab:
* :indentSize=4:tabSize=8:noTabs=true:
*/
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