12 static void trap(void)
18 static void validate_subtree(const struct quadtree *node)
25 printf("Attempted to validate a null pointer\n");
30 for (i = 0; i < 4; i++) {
34 if (node->child[i]->parent != node) {
35 printf("%s:%d Fatal! Tree inconsistency detected at "
36 "child %d %p in node %p, incorrent parent %p\n",
37 __func__, __LINE__, i, node->child[i], node,
38 node->child[i]->parent);
44 if (node->child[i] == node->parent) {
45 printf("%s:%d Fatal! Tree loop detected "
46 "at child %d in node %p\n",
47 __func__, __LINE__, i, node);
53 children += node->child[i]->children + 1;
55 validate_subtree(node->child[i]);
58 if (node->depth < 0) {
59 printf("%s:%d Tree statistics inconsistency detected! "
60 "Negative depth: %ld\n",
61 __func__, __LINE__, node->depth);
64 if (node->children != children) {
65 printf("%s:%d Tree statistics inconsistency detected! "
66 "child count mismatch. Expected %ld, got %ld\n",
67 __func__, __LINE__, children, node->children);
72 for (i = 0; i < 4 && node->children; i++) {
76 if (node->depth == node->child[i]->depth + 1)
79 if (node->child[i]->depth > node->depth) {
80 printf("%s:%d Tree statistics inconsistency detected! "
81 "child depth mismatch %ld > %ld\n",
82 __func__, __LINE__, node->child[i]->depth,
88 printf("%s:%d Tree statistics inconsistency detected! "
89 "child depth mismatch.",
96 static void validate_tree(const struct quadtree *node)
99 validate_subtree(quadtree_find_parent(node));
102 static int quadtree_compare(struct quadtree *a, struct quadtree *b)
106 up = b->pos.y < a->pos.y;
107 left = b->pos.x < a->pos.x;
119 * quadtree_add - add a node to a quadtree
120 * @parent: parent node
121 * @new: the new node to be added
123 * Add a node to a quadtree. The tree is kept in order, the new node
124 * is placed in the end of appropriate branch.
126 * The case of nodes sharing identical coordinates is not taken into
130 struct quadtree *quadtree_add(struct quadtree *parent, struct quadtree *new,
131 struct quadtree_ops *ops)
137 validate_tree(parent);
139 ret = quadtree_compare(parent, new);
141 if (ret < 0 || ret >= 4) {
142 printf("Invalid comparison result of %d\n", ret);
146 if (parent->child[ret])
147 return quadtree_add(parent->child[ret], new, ops);
149 parent->child[ret] = new;
150 new->parent = parent;
151 for (i = 0; i < 4; i++)
155 printf("adding node %p to parent %p\n", new, parent);
159 quadtree_recalculate_parent_stats(new, ops);
167 * _qt_optimal_del - Delete nodes from a detached subtree in optimal order
169 * All nodes are moved under the new parent node
171 static void _qt_optimal_del(struct quadtree *parent, struct quadtree *node,
172 struct quadtree_ops *ops, int parents)
174 struct quadtree *child[4] = {0};
175 int i, children = 0, max_c, max_i;
177 for (i = 0; i < 4; i++) {
178 if (!node->child[i]) {
183 child[children] = node->child[i];
184 node->child[i] = NULL;
189 * Try to remove the nodes in such order that the node which
190 * has child number one quarter of the parent's child numer
191 * gets deleted first.
194 if (node->children <= parents / 4) {
196 printf("%d: Moving node %p away from parent %p\n",
197 __LINE__, node, parent);
200 validate_tree(parent);
201 quadtree_add(parent, node, ops);
209 for (i = 0; i < 4; i++) {
213 if (max_c < child[i]->children) {
214 max_c = child[i]->children;
219 _qt_optimal_del(parent, child[max_i], ops, parents / 4);
225 validate_tree(parent);
227 printf("%d: Moving node %p away from parent %p\n",
228 __LINE__, node, parent);
231 quadtree_add(parent, node, ops);
236 * quadtree_del - Detach a node from the tree
238 * Return value: The new root node of the tree. If we are detaching
239 * anything but the root node of the entire tree, the returned root
240 * value will be the original root of the tree.
242 struct quadtree *quadtree_del(struct quadtree *node,
243 struct quadtree_ops *ops)
245 struct quadtree *parent = 0;
249 printf("Deleting node %p under parent %p\n",
254 * We are deleting the root node. This means we have to select
255 * a new root node and reconstruct the entire tree under it
259 for (i = 0; i < 4; i++) {
264 parent = node->child[i];
268 _qt_optimal_del(parent, node->child[i], ops,
277 * We are not deleting the parent. Detach the node from the
278 * parent abd relocate the children. The node will be then
279 * detached from the tree.
282 for (i = 0; i < 4; i++) {
283 if (node->parent->child[i] == node) {
284 node->parent->child[i] = 0;
291 parent = node->parent;
294 * The sub branch is now detached from the main tree. Fix the
297 quadtree_recalculate_parent_stats(node->parent, ops);
299 parent = quadtree_find_parent(parent);
301 if (node->children) {
302 for (i = 0; i < 4; i++) {
306 _qt_optimal_del(parent, node->child[i], ops,
311 validate_tree(parent);
316 static int _walk_tree(struct quadtree *head, const struct quadtree_iterator *it)
318 int direction, count = 0;
320 direction = it->direction(head, (struct quadtree_iterator *)it);
322 if ((direction & QUADTREE_UPLEFT) && head->child[0])
323 count += _walk_tree(head->child[0], it);
325 if ((direction & QUADTREE_UPRIGHT) && head->child[1])
326 count += _walk_tree(head->child[1], it);
328 if ((direction & QUADTREE_DOWNLEFT) && head->child[2])
329 count += _walk_tree(head->child[2], it);
331 if ((direction & QUADTREE_DOWNRIGHT) && head->child[3])
332 count += _walk_tree(head->child[3], it);
334 if ((direction & QUADTREE_SELF) && it->callback) {
335 it->callback(head, (struct quadtree_iterator *)it);
342 int walk_quadtree(const struct quadtree_iterator *it)
344 return _walk_tree(it->head, it);