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1 | /* |
2 | Red Black Trees | |
3 | (C) 1999 Andrea Arcangeli <[email protected]> | |
4 | (C) 2002 David Woodhouse <[email protected]> | |
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 <ubi_uboot.h> | |
24 | #include <linux/rbtree.h> | |
25 | ||
26 | static void __rb_rotate_left(struct rb_node *node, struct rb_root *root) | |
27 | { | |
28 | struct rb_node *right = node->rb_right; | |
29 | struct rb_node *parent = rb_parent(node); | |
30 | ||
31 | if ((node->rb_right = right->rb_left)) | |
32 | rb_set_parent(right->rb_left, node); | |
33 | right->rb_left = node; | |
34 | ||
35 | rb_set_parent(right, parent); | |
36 | ||
37 | if (parent) | |
38 | { | |
39 | if (node == parent->rb_left) | |
40 | parent->rb_left = right; | |
41 | else | |
42 | parent->rb_right = right; | |
43 | } | |
44 | else | |
45 | root->rb_node = right; | |
46 | rb_set_parent(node, right); | |
47 | } | |
48 | ||
49 | static void __rb_rotate_right(struct rb_node *node, struct rb_root *root) | |
50 | { | |
51 | struct rb_node *left = node->rb_left; | |
52 | struct rb_node *parent = rb_parent(node); | |
53 | ||
54 | if ((node->rb_left = left->rb_right)) | |
55 | rb_set_parent(left->rb_right, node); | |
56 | left->rb_right = node; | |
57 | ||
58 | rb_set_parent(left, parent); | |
59 | ||
60 | if (parent) | |
61 | { | |
62 | if (node == parent->rb_right) | |
63 | parent->rb_right = left; | |
64 | else | |
65 | parent->rb_left = left; | |
66 | } | |
67 | else | |
68 | root->rb_node = left; | |
69 | rb_set_parent(node, left); | |
70 | } | |
71 | ||
72 | void rb_insert_color(struct rb_node *node, struct rb_root *root) | |
73 | { | |
74 | struct rb_node *parent, *gparent; | |
75 | ||
76 | while ((parent = rb_parent(node)) && rb_is_red(parent)) | |
77 | { | |
78 | gparent = rb_parent(parent); | |
79 | ||
80 | if (parent == gparent->rb_left) | |
81 | { | |
82 | { | |
83 | register struct rb_node *uncle = gparent->rb_right; | |
84 | if (uncle && rb_is_red(uncle)) | |
85 | { | |
86 | rb_set_black(uncle); | |
87 | rb_set_black(parent); | |
88 | rb_set_red(gparent); | |
89 | node = gparent; | |
90 | continue; | |
91 | } | |
92 | } | |
93 | ||
94 | if (parent->rb_right == node) | |
95 | { | |
96 | register struct rb_node *tmp; | |
97 | __rb_rotate_left(parent, root); | |
98 | tmp = parent; | |
99 | parent = node; | |
100 | node = tmp; | |
101 | } | |
102 | ||
103 | rb_set_black(parent); | |
104 | rb_set_red(gparent); | |
105 | __rb_rotate_right(gparent, root); | |
106 | } else { | |
107 | { | |
108 | register struct rb_node *uncle = gparent->rb_left; | |
109 | if (uncle && rb_is_red(uncle)) | |
110 | { | |
111 | rb_set_black(uncle); | |
112 | rb_set_black(parent); | |
113 | rb_set_red(gparent); | |
114 | node = gparent; | |
115 | continue; | |
116 | } | |
117 | } | |
118 | ||
119 | if (parent->rb_left == node) | |
120 | { | |
121 | register struct rb_node *tmp; | |
122 | __rb_rotate_right(parent, root); | |
123 | tmp = parent; | |
124 | parent = node; | |
125 | node = tmp; | |
126 | } | |
127 | ||
128 | rb_set_black(parent); | |
129 | rb_set_red(gparent); | |
130 | __rb_rotate_left(gparent, root); | |
131 | } | |
132 | } | |
133 | ||
134 | rb_set_black(root->rb_node); | |
135 | } | |
136 | ||
137 | static void __rb_erase_color(struct rb_node *node, struct rb_node *parent, | |
138 | struct rb_root *root) | |
139 | { | |
140 | struct rb_node *other; | |
141 | ||
142 | while ((!node || rb_is_black(node)) && node != root->rb_node) | |
143 | { | |
144 | if (parent->rb_left == node) | |
145 | { | |
146 | other = parent->rb_right; | |
147 | if (rb_is_red(other)) | |
148 | { | |
149 | rb_set_black(other); | |
150 | rb_set_red(parent); | |
151 | __rb_rotate_left(parent, root); | |
152 | other = parent->rb_right; | |
153 | } | |
154 | if ((!other->rb_left || rb_is_black(other->rb_left)) && | |
155 | (!other->rb_right || rb_is_black(other->rb_right))) | |
156 | { | |
157 | rb_set_red(other); | |
158 | node = parent; | |
159 | parent = rb_parent(node); | |
160 | } | |
161 | else | |
162 | { | |
163 | if (!other->rb_right || rb_is_black(other->rb_right)) | |
164 | { | |
165 | struct rb_node *o_left; | |
166 | if ((o_left = other->rb_left)) | |
167 | rb_set_black(o_left); | |
168 | rb_set_red(other); | |
169 | __rb_rotate_right(other, root); | |
170 | other = parent->rb_right; | |
171 | } | |
172 | rb_set_color(other, rb_color(parent)); | |
173 | rb_set_black(parent); | |
174 | if (other->rb_right) | |
175 | rb_set_black(other->rb_right); | |
176 | __rb_rotate_left(parent, root); | |
177 | node = root->rb_node; | |
178 | break; | |
179 | } | |
180 | } | |
181 | else | |
182 | { | |
183 | other = parent->rb_left; | |
184 | if (rb_is_red(other)) | |
185 | { | |
186 | rb_set_black(other); | |
187 | rb_set_red(parent); | |
188 | __rb_rotate_right(parent, root); | |
189 | other = parent->rb_left; | |
190 | } | |
191 | if ((!other->rb_left || rb_is_black(other->rb_left)) && | |
192 | (!other->rb_right || rb_is_black(other->rb_right))) | |
193 | { | |
194 | rb_set_red(other); | |
195 | node = parent; | |
196 | parent = rb_parent(node); | |
197 | } | |
198 | else | |
199 | { | |
200 | if (!other->rb_left || rb_is_black(other->rb_left)) | |
201 | { | |
202 | register struct rb_node *o_right; | |
203 | if ((o_right = other->rb_right)) | |
204 | rb_set_black(o_right); | |
205 | rb_set_red(other); | |
206 | __rb_rotate_left(other, root); | |
207 | other = parent->rb_left; | |
208 | } | |
209 | rb_set_color(other, rb_color(parent)); | |
210 | rb_set_black(parent); | |
211 | if (other->rb_left) | |
212 | rb_set_black(other->rb_left); | |
213 | __rb_rotate_right(parent, root); | |
214 | node = root->rb_node; | |
215 | break; | |
216 | } | |
217 | } | |
218 | } | |
219 | if (node) | |
220 | rb_set_black(node); | |
221 | } | |
222 | ||
223 | void rb_erase(struct rb_node *node, struct rb_root *root) | |
224 | { | |
225 | struct rb_node *child, *parent; | |
226 | int color; | |
227 | ||
228 | if (!node->rb_left) | |
229 | child = node->rb_right; | |
230 | else if (!node->rb_right) | |
231 | child = node->rb_left; | |
232 | else | |
233 | { | |
234 | struct rb_node *old = node, *left; | |
235 | ||
236 | node = node->rb_right; | |
237 | while ((left = node->rb_left) != NULL) | |
238 | node = left; | |
239 | child = node->rb_right; | |
240 | parent = rb_parent(node); | |
241 | color = rb_color(node); | |
242 | ||
243 | if (child) | |
244 | rb_set_parent(child, parent); | |
245 | if (parent == old) { | |
246 | parent->rb_right = child; | |
247 | parent = node; | |
248 | } else | |
249 | parent->rb_left = child; | |
250 | ||
251 | node->rb_parent_color = old->rb_parent_color; | |
252 | node->rb_right = old->rb_right; | |
253 | node->rb_left = old->rb_left; | |
254 | ||
255 | if (rb_parent(old)) | |
256 | { | |
257 | if (rb_parent(old)->rb_left == old) | |
258 | rb_parent(old)->rb_left = node; | |
259 | else | |
260 | rb_parent(old)->rb_right = node; | |
261 | } else | |
262 | root->rb_node = node; | |
263 | ||
264 | rb_set_parent(old->rb_left, node); | |
265 | if (old->rb_right) | |
266 | rb_set_parent(old->rb_right, node); | |
267 | goto color; | |
268 | } | |
269 | ||
270 | parent = rb_parent(node); | |
271 | color = rb_color(node); | |
272 | ||
273 | if (child) | |
274 | rb_set_parent(child, parent); | |
275 | if (parent) | |
276 | { | |
277 | if (parent->rb_left == node) | |
278 | parent->rb_left = child; | |
279 | else | |
280 | parent->rb_right = child; | |
281 | } | |
282 | else | |
283 | root->rb_node = child; | |
284 | ||
285 | color: | |
286 | if (color == RB_BLACK) | |
287 | __rb_erase_color(child, parent, root); | |
288 | } | |
289 | ||
290 | /* | |
291 | * This function returns the first node (in sort order) of the tree. | |
292 | */ | |
293 | struct rb_node *rb_first(struct rb_root *root) | |
294 | { | |
295 | struct rb_node *n; | |
296 | ||
297 | n = root->rb_node; | |
298 | if (!n) | |
299 | return NULL; | |
300 | while (n->rb_left) | |
301 | n = n->rb_left; | |
302 | return n; | |
303 | } | |
304 | ||
305 | struct rb_node *rb_last(struct rb_root *root) | |
306 | { | |
307 | struct rb_node *n; | |
308 | ||
309 | n = root->rb_node; | |
310 | if (!n) | |
311 | return NULL; | |
312 | while (n->rb_right) | |
313 | n = n->rb_right; | |
314 | return n; | |
315 | } | |
316 | ||
317 | struct rb_node *rb_next(struct rb_node *node) | |
318 | { | |
319 | struct rb_node *parent; | |
320 | ||
321 | if (rb_parent(node) == node) | |
322 | return NULL; | |
323 | ||
324 | /* If we have a right-hand child, go down and then left as far | |
325 | as we can. */ | |
326 | if (node->rb_right) { | |
327 | node = node->rb_right; | |
328 | while (node->rb_left) | |
329 | node=node->rb_left; | |
330 | return node; | |
331 | } | |
332 | ||
333 | /* No right-hand children. Everything down and left is | |
334 | smaller than us, so any 'next' node must be in the general | |
335 | direction of our parent. Go up the tree; any time the | |
336 | ancestor is a right-hand child of its parent, keep going | |
337 | up. First time it's a left-hand child of its parent, said | |
338 | parent is our 'next' node. */ | |
339 | while ((parent = rb_parent(node)) && node == parent->rb_right) | |
340 | node = parent; | |
341 | ||
342 | return parent; | |
343 | } | |
344 | ||
345 | struct rb_node *rb_prev(struct rb_node *node) | |
346 | { | |
347 | struct rb_node *parent; | |
348 | ||
349 | if (rb_parent(node) == node) | |
350 | return NULL; | |
351 | ||
352 | /* If we have a left-hand child, go down and then right as far | |
353 | as we can. */ | |
354 | if (node->rb_left) { | |
355 | node = node->rb_left; | |
356 | while (node->rb_right) | |
357 | node=node->rb_right; | |
358 | return node; | |
359 | } | |
360 | ||
361 | /* No left-hand children. Go up till we find an ancestor which | |
362 | is a right-hand child of its parent */ | |
363 | while ((parent = rb_parent(node)) && node == parent->rb_left) | |
364 | node = parent; | |
365 | ||
366 | return parent; | |
367 | } | |
368 | ||
369 | void rb_replace_node(struct rb_node *victim, struct rb_node *new, | |
370 | struct rb_root *root) | |
371 | { | |
372 | struct rb_node *parent = rb_parent(victim); | |
373 | ||
374 | /* Set the surrounding nodes to point to the replacement */ | |
375 | if (parent) { | |
376 | if (victim == parent->rb_left) | |
377 | parent->rb_left = new; | |
378 | else | |
379 | parent->rb_right = new; | |
380 | } else { | |
381 | root->rb_node = new; | |
382 | } | |
383 | if (victim->rb_left) | |
384 | rb_set_parent(victim->rb_left, new); | |
385 | if (victim->rb_right) | |
386 | rb_set_parent(victim->rb_right, new); | |
387 | ||
388 | /* Copy the pointers/colour from the victim to the replacement */ | |
389 | *new = *victim; | |
390 | } |