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