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Commit | Line | Data |
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1da177e4 LT |
1 | /* |
2 | Red Black Trees | |
3 | (C) 1999 Andrea Arcangeli <andrea@suse.de> | |
4 | (C) 2002 David Woodhouse <dwmw2@infradead.org> | |
5 | ||
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. | |
10 | ||
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. | |
15 | ||
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 | |
19 | ||
20 | linux/lib/rbtree.c | |
21 | */ | |
22 | ||
23 | #include <linux/rbtree.h> | |
8bc3bcc9 | 24 | #include <linux/export.h> |
1da177e4 | 25 | |
bf7ad8ee ML |
26 | #define RB_RED 0 |
27 | #define RB_BLACK 1 | |
28 | ||
29 | #define rb_color(r) ((r)->__rb_parent_color & 1) | |
30 | #define rb_is_red(r) (!rb_color(r)) | |
31 | #define rb_is_black(r) rb_color(r) | |
32 | #define rb_set_red(r) do { (r)->__rb_parent_color &= ~1; } while (0) | |
33 | #define rb_set_black(r) do { (r)->__rb_parent_color |= 1; } while (0) | |
34 | ||
35 | static inline void rb_set_parent(struct rb_node *rb, struct rb_node *p) | |
36 | { | |
37 | rb->__rb_parent_color = rb_color(rb) | (unsigned long)p; | |
38 | } | |
39 | static inline void rb_set_color(struct rb_node *rb, int color) | |
40 | { | |
41 | rb->__rb_parent_color = (rb->__rb_parent_color & ~1) | color; | |
42 | } | |
43 | ||
1da177e4 LT |
44 | static void __rb_rotate_left(struct rb_node *node, struct rb_root *root) |
45 | { | |
46 | struct rb_node *right = node->rb_right; | |
55a98102 | 47 | struct rb_node *parent = rb_parent(node); |
1da177e4 LT |
48 | |
49 | if ((node->rb_right = right->rb_left)) | |
55a98102 | 50 | rb_set_parent(right->rb_left, node); |
1da177e4 LT |
51 | right->rb_left = node; |
52 | ||
55a98102 DW |
53 | rb_set_parent(right, parent); |
54 | ||
55 | if (parent) | |
1da177e4 | 56 | { |
55a98102 DW |
57 | if (node == parent->rb_left) |
58 | parent->rb_left = right; | |
1da177e4 | 59 | else |
55a98102 | 60 | parent->rb_right = right; |
1da177e4 LT |
61 | } |
62 | else | |
63 | root->rb_node = right; | |
55a98102 | 64 | rb_set_parent(node, right); |
1da177e4 LT |
65 | } |
66 | ||
67 | static void __rb_rotate_right(struct rb_node *node, struct rb_root *root) | |
68 | { | |
69 | struct rb_node *left = node->rb_left; | |
55a98102 | 70 | struct rb_node *parent = rb_parent(node); |
1da177e4 LT |
71 | |
72 | if ((node->rb_left = left->rb_right)) | |
55a98102 | 73 | rb_set_parent(left->rb_right, node); |
1da177e4 LT |
74 | left->rb_right = node; |
75 | ||
55a98102 DW |
76 | rb_set_parent(left, parent); |
77 | ||
78 | if (parent) | |
1da177e4 | 79 | { |
55a98102 DW |
80 | if (node == parent->rb_right) |
81 | parent->rb_right = left; | |
1da177e4 | 82 | else |
55a98102 | 83 | parent->rb_left = left; |
1da177e4 LT |
84 | } |
85 | else | |
86 | root->rb_node = left; | |
55a98102 | 87 | rb_set_parent(node, left); |
1da177e4 LT |
88 | } |
89 | ||
90 | void rb_insert_color(struct rb_node *node, struct rb_root *root) | |
91 | { | |
92 | struct rb_node *parent, *gparent; | |
93 | ||
6d58452d ML |
94 | while (true) { |
95 | /* | |
96 | * Loop invariant: node is red | |
97 | * | |
98 | * If there is a black parent, we are done. | |
99 | * Otherwise, take some corrective action as we don't | |
100 | * want a red root or two consecutive red nodes. | |
101 | */ | |
102 | parent = rb_parent(node); | |
103 | if (!parent) { | |
104 | rb_set_black(node); | |
105 | break; | |
106 | } else if (rb_is_black(parent)) | |
107 | break; | |
108 | ||
55a98102 | 109 | gparent = rb_parent(parent); |
1da177e4 LT |
110 | |
111 | if (parent == gparent->rb_left) | |
112 | { | |
113 | { | |
114 | register struct rb_node *uncle = gparent->rb_right; | |
55a98102 | 115 | if (uncle && rb_is_red(uncle)) |
1da177e4 | 116 | { |
55a98102 DW |
117 | rb_set_black(uncle); |
118 | rb_set_black(parent); | |
119 | rb_set_red(gparent); | |
1da177e4 LT |
120 | node = gparent; |
121 | continue; | |
122 | } | |
123 | } | |
124 | ||
1f052865 | 125 | if (parent->rb_right == node) { |
1da177e4 | 126 | __rb_rotate_left(parent, root); |
1da177e4 | 127 | parent = node; |
1da177e4 LT |
128 | } |
129 | ||
55a98102 DW |
130 | rb_set_black(parent); |
131 | rb_set_red(gparent); | |
1da177e4 | 132 | __rb_rotate_right(gparent, root); |
1f052865 | 133 | break; |
1da177e4 LT |
134 | } else { |
135 | { | |
136 | register struct rb_node *uncle = gparent->rb_left; | |
55a98102 | 137 | if (uncle && rb_is_red(uncle)) |
1da177e4 | 138 | { |
55a98102 DW |
139 | rb_set_black(uncle); |
140 | rb_set_black(parent); | |
141 | rb_set_red(gparent); | |
1da177e4 LT |
142 | node = gparent; |
143 | continue; | |
144 | } | |
145 | } | |
146 | ||
1f052865 | 147 | if (parent->rb_left == node) { |
1da177e4 | 148 | __rb_rotate_right(parent, root); |
1da177e4 | 149 | parent = node; |
1da177e4 LT |
150 | } |
151 | ||
55a98102 DW |
152 | rb_set_black(parent); |
153 | rb_set_red(gparent); | |
1da177e4 | 154 | __rb_rotate_left(gparent, root); |
1f052865 | 155 | break; |
1da177e4 LT |
156 | } |
157 | } | |
1da177e4 LT |
158 | } |
159 | EXPORT_SYMBOL(rb_insert_color); | |
160 | ||
161 | static void __rb_erase_color(struct rb_node *node, struct rb_node *parent, | |
162 | struct rb_root *root) | |
163 | { | |
164 | struct rb_node *other; | |
165 | ||
55a98102 | 166 | while ((!node || rb_is_black(node)) && node != root->rb_node) |
1da177e4 LT |
167 | { |
168 | if (parent->rb_left == node) | |
169 | { | |
170 | other = parent->rb_right; | |
55a98102 | 171 | if (rb_is_red(other)) |
1da177e4 | 172 | { |
55a98102 DW |
173 | rb_set_black(other); |
174 | rb_set_red(parent); | |
1da177e4 LT |
175 | __rb_rotate_left(parent, root); |
176 | other = parent->rb_right; | |
177 | } | |
55a98102 DW |
178 | if ((!other->rb_left || rb_is_black(other->rb_left)) && |
179 | (!other->rb_right || rb_is_black(other->rb_right))) | |
1da177e4 | 180 | { |
55a98102 | 181 | rb_set_red(other); |
1da177e4 | 182 | node = parent; |
55a98102 | 183 | parent = rb_parent(node); |
1da177e4 LT |
184 | } |
185 | else | |
186 | { | |
55a98102 | 187 | if (!other->rb_right || rb_is_black(other->rb_right)) |
1da177e4 | 188 | { |
55a63998 | 189 | rb_set_black(other->rb_left); |
55a98102 | 190 | rb_set_red(other); |
1da177e4 LT |
191 | __rb_rotate_right(other, root); |
192 | other = parent->rb_right; | |
193 | } | |
2f3243ae | 194 | rb_set_color(other, rb_color(parent)); |
55a98102 | 195 | rb_set_black(parent); |
55a63998 | 196 | rb_set_black(other->rb_right); |
1da177e4 LT |
197 | __rb_rotate_left(parent, root); |
198 | node = root->rb_node; | |
199 | break; | |
200 | } | |
201 | } | |
202 | else | |
203 | { | |
204 | other = parent->rb_left; | |
55a98102 | 205 | if (rb_is_red(other)) |
1da177e4 | 206 | { |
55a98102 DW |
207 | rb_set_black(other); |
208 | rb_set_red(parent); | |
1da177e4 LT |
209 | __rb_rotate_right(parent, root); |
210 | other = parent->rb_left; | |
211 | } | |
55a98102 DW |
212 | if ((!other->rb_left || rb_is_black(other->rb_left)) && |
213 | (!other->rb_right || rb_is_black(other->rb_right))) | |
1da177e4 | 214 | { |
55a98102 | 215 | rb_set_red(other); |
1da177e4 | 216 | node = parent; |
55a98102 | 217 | parent = rb_parent(node); |
1da177e4 LT |
218 | } |
219 | else | |
220 | { | |
55a98102 | 221 | if (!other->rb_left || rb_is_black(other->rb_left)) |
1da177e4 | 222 | { |
55a63998 | 223 | rb_set_black(other->rb_right); |
55a98102 | 224 | rb_set_red(other); |
1da177e4 LT |
225 | __rb_rotate_left(other, root); |
226 | other = parent->rb_left; | |
227 | } | |
2f3243ae | 228 | rb_set_color(other, rb_color(parent)); |
55a98102 | 229 | rb_set_black(parent); |
55a63998 | 230 | rb_set_black(other->rb_left); |
1da177e4 LT |
231 | __rb_rotate_right(parent, root); |
232 | node = root->rb_node; | |
233 | break; | |
234 | } | |
235 | } | |
236 | } | |
237 | if (node) | |
55a98102 | 238 | rb_set_black(node); |
1da177e4 LT |
239 | } |
240 | ||
241 | void rb_erase(struct rb_node *node, struct rb_root *root) | |
242 | { | |
243 | struct rb_node *child, *parent; | |
244 | int color; | |
245 | ||
246 | if (!node->rb_left) | |
247 | child = node->rb_right; | |
248 | else if (!node->rb_right) | |
249 | child = node->rb_left; | |
250 | else | |
251 | { | |
252 | struct rb_node *old = node, *left; | |
253 | ||
254 | node = node->rb_right; | |
255 | while ((left = node->rb_left) != NULL) | |
256 | node = left; | |
16c047ad WS |
257 | |
258 | if (rb_parent(old)) { | |
259 | if (rb_parent(old)->rb_left == old) | |
260 | rb_parent(old)->rb_left = node; | |
261 | else | |
262 | rb_parent(old)->rb_right = node; | |
263 | } else | |
264 | root->rb_node = node; | |
265 | ||
1da177e4 | 266 | child = node->rb_right; |
55a98102 | 267 | parent = rb_parent(node); |
2f3243ae | 268 | color = rb_color(node); |
1da177e4 | 269 | |
55a98102 | 270 | if (parent == old) { |
1da177e4 | 271 | parent = node; |
4c601178 WS |
272 | } else { |
273 | if (child) | |
274 | rb_set_parent(child, parent); | |
1975e593 | 275 | parent->rb_left = child; |
4b324126 WS |
276 | |
277 | node->rb_right = old->rb_right; | |
278 | rb_set_parent(old->rb_right, node); | |
4c601178 | 279 | } |
1975e593 | 280 | |
bf7ad8ee | 281 | node->__rb_parent_color = old->__rb_parent_color; |
1da177e4 | 282 | node->rb_left = old->rb_left; |
55a98102 | 283 | rb_set_parent(old->rb_left, node); |
4b324126 | 284 | |
1da177e4 LT |
285 | goto color; |
286 | } | |
287 | ||
55a98102 | 288 | parent = rb_parent(node); |
2f3243ae | 289 | color = rb_color(node); |
1da177e4 LT |
290 | |
291 | if (child) | |
55a98102 | 292 | rb_set_parent(child, parent); |
b945d6b2 PZ |
293 | if (parent) |
294 | { | |
1da177e4 LT |
295 | if (parent->rb_left == node) |
296 | parent->rb_left = child; | |
297 | else | |
298 | parent->rb_right = child; | |
17d9ddc7 | 299 | } |
b945d6b2 PZ |
300 | else |
301 | root->rb_node = child; | |
1da177e4 LT |
302 | |
303 | color: | |
304 | if (color == RB_BLACK) | |
305 | __rb_erase_color(child, parent, root); | |
306 | } | |
307 | EXPORT_SYMBOL(rb_erase); | |
308 | ||
b945d6b2 PZ |
309 | static void rb_augment_path(struct rb_node *node, rb_augment_f func, void *data) |
310 | { | |
311 | struct rb_node *parent; | |
312 | ||
313 | up: | |
314 | func(node, data); | |
315 | parent = rb_parent(node); | |
316 | if (!parent) | |
317 | return; | |
318 | ||
319 | if (node == parent->rb_left && parent->rb_right) | |
320 | func(parent->rb_right, data); | |
321 | else if (parent->rb_left) | |
322 | func(parent->rb_left, data); | |
323 | ||
324 | node = parent; | |
325 | goto up; | |
326 | } | |
327 | ||
328 | /* | |
329 | * after inserting @node into the tree, update the tree to account for | |
330 | * both the new entry and any damage done by rebalance | |
331 | */ | |
332 | void rb_augment_insert(struct rb_node *node, rb_augment_f func, void *data) | |
333 | { | |
334 | if (node->rb_left) | |
335 | node = node->rb_left; | |
336 | else if (node->rb_right) | |
337 | node = node->rb_right; | |
338 | ||
339 | rb_augment_path(node, func, data); | |
340 | } | |
0b6bb66d | 341 | EXPORT_SYMBOL(rb_augment_insert); |
b945d6b2 PZ |
342 | |
343 | /* | |
344 | * before removing the node, find the deepest node on the rebalance path | |
345 | * that will still be there after @node gets removed | |
346 | */ | |
347 | struct rb_node *rb_augment_erase_begin(struct rb_node *node) | |
348 | { | |
349 | struct rb_node *deepest; | |
350 | ||
351 | if (!node->rb_right && !node->rb_left) | |
352 | deepest = rb_parent(node); | |
353 | else if (!node->rb_right) | |
354 | deepest = node->rb_left; | |
355 | else if (!node->rb_left) | |
356 | deepest = node->rb_right; | |
357 | else { | |
358 | deepest = rb_next(node); | |
359 | if (deepest->rb_right) | |
360 | deepest = deepest->rb_right; | |
361 | else if (rb_parent(deepest) != node) | |
362 | deepest = rb_parent(deepest); | |
363 | } | |
364 | ||
365 | return deepest; | |
366 | } | |
0b6bb66d | 367 | EXPORT_SYMBOL(rb_augment_erase_begin); |
b945d6b2 PZ |
368 | |
369 | /* | |
370 | * after removal, update the tree to account for the removed entry | |
371 | * and any rebalance damage. | |
372 | */ | |
373 | void rb_augment_erase_end(struct rb_node *node, rb_augment_f func, void *data) | |
374 | { | |
375 | if (node) | |
376 | rb_augment_path(node, func, data); | |
377 | } | |
0b6bb66d | 378 | EXPORT_SYMBOL(rb_augment_erase_end); |
b945d6b2 | 379 | |
1da177e4 LT |
380 | /* |
381 | * This function returns the first node (in sort order) of the tree. | |
382 | */ | |
f4b477c4 | 383 | struct rb_node *rb_first(const struct rb_root *root) |
1da177e4 LT |
384 | { |
385 | struct rb_node *n; | |
386 | ||
387 | n = root->rb_node; | |
388 | if (!n) | |
389 | return NULL; | |
390 | while (n->rb_left) | |
391 | n = n->rb_left; | |
392 | return n; | |
393 | } | |
394 | EXPORT_SYMBOL(rb_first); | |
395 | ||
f4b477c4 | 396 | struct rb_node *rb_last(const struct rb_root *root) |
1da177e4 LT |
397 | { |
398 | struct rb_node *n; | |
399 | ||
400 | n = root->rb_node; | |
401 | if (!n) | |
402 | return NULL; | |
403 | while (n->rb_right) | |
404 | n = n->rb_right; | |
405 | return n; | |
406 | } | |
407 | EXPORT_SYMBOL(rb_last); | |
408 | ||
f4b477c4 | 409 | struct rb_node *rb_next(const struct rb_node *node) |
1da177e4 | 410 | { |
55a98102 DW |
411 | struct rb_node *parent; |
412 | ||
4c199a93 | 413 | if (RB_EMPTY_NODE(node)) |
10fd48f2 JA |
414 | return NULL; |
415 | ||
1da177e4 LT |
416 | /* If we have a right-hand child, go down and then left as far |
417 | as we can. */ | |
418 | if (node->rb_right) { | |
419 | node = node->rb_right; | |
420 | while (node->rb_left) | |
421 | node=node->rb_left; | |
f4b477c4 | 422 | return (struct rb_node *)node; |
1da177e4 LT |
423 | } |
424 | ||
425 | /* No right-hand children. Everything down and left is | |
426 | smaller than us, so any 'next' node must be in the general | |
427 | direction of our parent. Go up the tree; any time the | |
428 | ancestor is a right-hand child of its parent, keep going | |
429 | up. First time it's a left-hand child of its parent, said | |
430 | parent is our 'next' node. */ | |
55a98102 DW |
431 | while ((parent = rb_parent(node)) && node == parent->rb_right) |
432 | node = parent; | |
1da177e4 | 433 | |
55a98102 | 434 | return parent; |
1da177e4 LT |
435 | } |
436 | EXPORT_SYMBOL(rb_next); | |
437 | ||
f4b477c4 | 438 | struct rb_node *rb_prev(const struct rb_node *node) |
1da177e4 | 439 | { |
55a98102 DW |
440 | struct rb_node *parent; |
441 | ||
4c199a93 | 442 | if (RB_EMPTY_NODE(node)) |
10fd48f2 JA |
443 | return NULL; |
444 | ||
1da177e4 LT |
445 | /* If we have a left-hand child, go down and then right as far |
446 | as we can. */ | |
447 | if (node->rb_left) { | |
448 | node = node->rb_left; | |
449 | while (node->rb_right) | |
450 | node=node->rb_right; | |
f4b477c4 | 451 | return (struct rb_node *)node; |
1da177e4 LT |
452 | } |
453 | ||
454 | /* No left-hand children. Go up till we find an ancestor which | |
455 | is a right-hand child of its parent */ | |
55a98102 DW |
456 | while ((parent = rb_parent(node)) && node == parent->rb_left) |
457 | node = parent; | |
1da177e4 | 458 | |
55a98102 | 459 | return parent; |
1da177e4 LT |
460 | } |
461 | EXPORT_SYMBOL(rb_prev); | |
462 | ||
463 | void rb_replace_node(struct rb_node *victim, struct rb_node *new, | |
464 | struct rb_root *root) | |
465 | { | |
55a98102 | 466 | struct rb_node *parent = rb_parent(victim); |
1da177e4 LT |
467 | |
468 | /* Set the surrounding nodes to point to the replacement */ | |
469 | if (parent) { | |
470 | if (victim == parent->rb_left) | |
471 | parent->rb_left = new; | |
472 | else | |
473 | parent->rb_right = new; | |
474 | } else { | |
475 | root->rb_node = new; | |
476 | } | |
477 | if (victim->rb_left) | |
55a98102 | 478 | rb_set_parent(victim->rb_left, new); |
1da177e4 | 479 | if (victim->rb_right) |
55a98102 | 480 | rb_set_parent(victim->rb_right, new); |
1da177e4 LT |
481 | |
482 | /* Copy the pointers/colour from the victim to the replacement */ | |
483 | *new = *victim; | |
484 | } | |
485 | EXPORT_SYMBOL(rb_replace_node); |