3 (C) 1999 Andrea Arcangeli <andrea@suse.de>
4 (C) 2002 David Woodhouse <dwmw2@infradead.org>
6 This program is free software; you can redistribute it and/or modify
7 it under the terms of the GNU General Public License as published by
8 the Free Software Foundation; either version 2 of the License, or
9 (at your option) any later version.
11 This program is distributed in the hope that it will be useful,
12 but WITHOUT ANY WARRANTY; without even the implied warranty of
13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 GNU General Public License for more details.
16 You should have received a copy of the GNU General Public License
17 along with this program; if not, write to the Free Software
18 Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
23 #include <linux/rbtree.h>
24 #include <linux/module.h>
26 static void __rb_rotate_left(struct rb_node *node, struct rb_root *root)
28 struct rb_node *right = node->rb_right;
29 struct rb_node *parent = rb_parent(node);
31 if ((node->rb_right = right->rb_left))
32 rb_set_parent(right->rb_left, node);
33 right->rb_left = node;
35 rb_set_parent(right, parent);
39 if (node == parent->rb_left)
40 parent->rb_left = right;
42 parent->rb_right = right;
45 root->rb_node = right;
46 rb_set_parent(node, right);
49 static void __rb_rotate_right(struct rb_node *node, struct rb_root *root)
51 struct rb_node *left = node->rb_left;
52 struct rb_node *parent = rb_parent(node);
54 if ((node->rb_left = left->rb_right))
55 rb_set_parent(left->rb_right, node);
56 left->rb_right = node;
58 rb_set_parent(left, parent);
62 if (node == parent->rb_right)
63 parent->rb_right = left;
65 parent->rb_left = left;
69 rb_set_parent(node, left);
72 void rb_insert_color(struct rb_node *node, struct rb_root *root)
74 struct rb_node *parent, *gparent;
76 while ((parent = rb_parent(node)) && rb_is_red(parent))
78 gparent = rb_parent(parent);
80 if (parent == gparent->rb_left)
83 register struct rb_node *uncle = gparent->rb_right;
84 if (uncle && rb_is_red(uncle))
94 if (parent->rb_right == node)
96 register struct rb_node *tmp;
97 __rb_rotate_left(parent, root);
103 rb_set_black(parent);
105 __rb_rotate_right(gparent, root);
108 register struct rb_node *uncle = gparent->rb_left;
109 if (uncle && rb_is_red(uncle))
112 rb_set_black(parent);
119 if (parent->rb_left == node)
121 register struct rb_node *tmp;
122 __rb_rotate_right(parent, root);
128 rb_set_black(parent);
130 __rb_rotate_left(gparent, root);
134 rb_set_black(root->rb_node);
136 EXPORT_SYMBOL(rb_insert_color);
138 static void __rb_erase_color(struct rb_node *node, struct rb_node *parent,
139 struct rb_root *root)
141 struct rb_node *other;
143 while ((!node || rb_is_black(node)) && node != root->rb_node)
145 if (parent->rb_left == node)
147 other = parent->rb_right;
148 if (rb_is_red(other))
152 __rb_rotate_left(parent, root);
153 other = parent->rb_right;
155 if ((!other->rb_left || rb_is_black(other->rb_left)) &&
156 (!other->rb_right || rb_is_black(other->rb_right)))
160 parent = rb_parent(node);
164 if (!other->rb_right || rb_is_black(other->rb_right))
166 rb_set_black(other->rb_left);
168 __rb_rotate_right(other, root);
169 other = parent->rb_right;
171 rb_set_color(other, rb_color(parent));
172 rb_set_black(parent);
173 rb_set_black(other->rb_right);
174 __rb_rotate_left(parent, root);
175 node = root->rb_node;
181 other = parent->rb_left;
182 if (rb_is_red(other))
186 __rb_rotate_right(parent, root);
187 other = parent->rb_left;
189 if ((!other->rb_left || rb_is_black(other->rb_left)) &&
190 (!other->rb_right || rb_is_black(other->rb_right)))
194 parent = rb_parent(node);
198 if (!other->rb_left || rb_is_black(other->rb_left))
200 rb_set_black(other->rb_right);
202 __rb_rotate_left(other, root);
203 other = parent->rb_left;
205 rb_set_color(other, rb_color(parent));
206 rb_set_black(parent);
207 rb_set_black(other->rb_left);
208 __rb_rotate_right(parent, root);
209 node = root->rb_node;
218 void rb_erase(struct rb_node *node, struct rb_root *root)
220 struct rb_node *child, *parent;
224 child = node->rb_right;
225 else if (!node->rb_right)
226 child = node->rb_left;
229 struct rb_node *old = node, *left;
231 node = node->rb_right;
232 while ((left = node->rb_left) != NULL)
235 if (rb_parent(old)) {
236 if (rb_parent(old)->rb_left == old)
237 rb_parent(old)->rb_left = node;
239 rb_parent(old)->rb_right = node;
241 root->rb_node = node;
243 child = node->rb_right;
244 parent = rb_parent(node);
245 color = rb_color(node);
251 rb_set_parent(child, parent);
252 parent->rb_left = child;
254 node->rb_right = old->rb_right;
255 rb_set_parent(old->rb_right, node);
258 node->rb_parent_color = old->rb_parent_color;
259 node->rb_left = old->rb_left;
260 rb_set_parent(old->rb_left, node);
265 parent = rb_parent(node);
266 color = rb_color(node);
269 rb_set_parent(child, parent);
272 if (parent->rb_left == node)
273 parent->rb_left = child;
275 parent->rb_right = child;
278 root->rb_node = child;
281 if (color == RB_BLACK)
282 __rb_erase_color(child, parent, root);
284 EXPORT_SYMBOL(rb_erase);
286 static void rb_augment_path(struct rb_node *node, rb_augment_f func, void *data)
288 struct rb_node *parent;
292 parent = rb_parent(node);
296 if (node == parent->rb_left && parent->rb_right)
297 func(parent->rb_right, data);
298 else if (parent->rb_left)
299 func(parent->rb_left, data);
306 * after inserting @node into the tree, update the tree to account for
307 * both the new entry and any damage done by rebalance
309 void rb_augment_insert(struct rb_node *node, rb_augment_f func, void *data)
312 node = node->rb_left;
313 else if (node->rb_right)
314 node = node->rb_right;
316 rb_augment_path(node, func, data);
320 * before removing the node, find the deepest node on the rebalance path
321 * that will still be there after @node gets removed
323 struct rb_node *rb_augment_erase_begin(struct rb_node *node)
325 struct rb_node *deepest;
327 if (!node->rb_right && !node->rb_left)
328 deepest = rb_parent(node);
329 else if (!node->rb_right)
330 deepest = node->rb_left;
331 else if (!node->rb_left)
332 deepest = node->rb_right;
334 deepest = rb_next(node);
335 if (deepest->rb_right)
336 deepest = deepest->rb_right;
337 else if (rb_parent(deepest) != node)
338 deepest = rb_parent(deepest);
345 * after removal, update the tree to account for the removed entry
346 * and any rebalance damage.
348 void rb_augment_erase_end(struct rb_node *node, rb_augment_f func, void *data)
351 rb_augment_path(node, func, data);
355 * This function returns the first node (in sort order) of the tree.
357 struct rb_node *rb_first(const struct rb_root *root)
368 EXPORT_SYMBOL(rb_first);
370 struct rb_node *rb_last(const struct rb_root *root)
381 EXPORT_SYMBOL(rb_last);
383 struct rb_node *rb_next(const struct rb_node *node)
385 struct rb_node *parent;
387 if (rb_parent(node) == node)
390 /* If we have a right-hand child, go down and then left as far
392 if (node->rb_right) {
393 node = node->rb_right;
394 while (node->rb_left)
396 return (struct rb_node *)node;
399 /* No right-hand children. Everything down and left is
400 smaller than us, so any 'next' node must be in the general
401 direction of our parent. Go up the tree; any time the
402 ancestor is a right-hand child of its parent, keep going
403 up. First time it's a left-hand child of its parent, said
404 parent is our 'next' node. */
405 while ((parent = rb_parent(node)) && node == parent->rb_right)
410 EXPORT_SYMBOL(rb_next);
412 struct rb_node *rb_prev(const struct rb_node *node)
414 struct rb_node *parent;
416 if (rb_parent(node) == node)
419 /* If we have a left-hand child, go down and then right as far
422 node = node->rb_left;
423 while (node->rb_right)
425 return (struct rb_node *)node;
428 /* No left-hand children. Go up till we find an ancestor which
429 is a right-hand child of its parent */
430 while ((parent = rb_parent(node)) && node == parent->rb_left)
435 EXPORT_SYMBOL(rb_prev);
437 void rb_replace_node(struct rb_node *victim, struct rb_node *new,
438 struct rb_root *root)
440 struct rb_node *parent = rb_parent(victim);
442 /* Set the surrounding nodes to point to the replacement */
444 if (victim == parent->rb_left)
445 parent->rb_left = new;
447 parent->rb_right = new;
452 rb_set_parent(victim->rb_left, new);
453 if (victim->rb_right)
454 rb_set_parent(victim->rb_right, new);
456 /* Copy the pointers/colour from the victim to the replacement */
459 EXPORT_SYMBOL(rb_replace_node);