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-rw-r--r--Documentation/perf_counter/util/rbtree.c383
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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 "rbtree.h"
24
25static void __rb_rotate_left(struct rb_node *node, struct rb_root *root)
26{
27 struct rb_node *right = node->rb_right;
28 struct rb_node *parent = rb_parent(node);
29
30 if ((node->rb_right = right->rb_left))
31 rb_set_parent(right->rb_left, node);
32 right->rb_left = node;
33
34 rb_set_parent(right, parent);
35
36 if (parent)
37 {
38 if (node == parent->rb_left)
39 parent->rb_left = right;
40 else
41 parent->rb_right = right;
42 }
43 else
44 root->rb_node = right;
45 rb_set_parent(node, right);
46}
47
48static void __rb_rotate_right(struct rb_node *node, struct rb_root *root)
49{
50 struct rb_node *left = node->rb_left;
51 struct rb_node *parent = rb_parent(node);
52
53 if ((node->rb_left = left->rb_right))
54 rb_set_parent(left->rb_right, node);
55 left->rb_right = node;
56
57 rb_set_parent(left, parent);
58
59 if (parent)
60 {
61 if (node == parent->rb_right)
62 parent->rb_right = left;
63 else
64 parent->rb_left = left;
65 }
66 else
67 root->rb_node = left;
68 rb_set_parent(node, left);
69}
70
71void rb_insert_color(struct rb_node *node, struct rb_root *root)
72{
73 struct rb_node *parent, *gparent;
74
75 while ((parent = rb_parent(node)) && rb_is_red(parent))
76 {
77 gparent = rb_parent(parent);
78
79 if (parent == gparent->rb_left)
80 {
81 {
82 register struct rb_node *uncle = gparent->rb_right;
83 if (uncle && rb_is_red(uncle))
84 {
85 rb_set_black(uncle);
86 rb_set_black(parent);
87 rb_set_red(gparent);
88 node = gparent;
89 continue;
90 }
91 }
92
93 if (parent->rb_right == node)
94 {
95 register struct rb_node *tmp;
96 __rb_rotate_left(parent, root);
97 tmp = parent;
98 parent = node;
99 node = tmp;
100 }
101
102 rb_set_black(parent);
103 rb_set_red(gparent);
104 __rb_rotate_right(gparent, root);
105 } else {
106 {
107 register struct rb_node *uncle = gparent->rb_left;
108 if (uncle && rb_is_red(uncle))
109 {
110 rb_set_black(uncle);
111 rb_set_black(parent);
112 rb_set_red(gparent);
113 node = gparent;
114 continue;
115 }
116 }
117
118 if (parent->rb_left == node)
119 {
120 register struct rb_node *tmp;
121 __rb_rotate_right(parent, root);
122 tmp = parent;
123 parent = node;
124 node = tmp;
125 }
126
127 rb_set_black(parent);
128 rb_set_red(gparent);
129 __rb_rotate_left(gparent, root);
130 }
131 }
132
133 rb_set_black(root->rb_node);
134}
135
136static void __rb_erase_color(struct rb_node *node, struct rb_node *parent,
137 struct rb_root *root)
138{
139 struct rb_node *other;
140
141 while ((!node || rb_is_black(node)) && node != root->rb_node)
142 {
143 if (parent->rb_left == node)
144 {
145 other = parent->rb_right;
146 if (rb_is_red(other))
147 {
148 rb_set_black(other);
149 rb_set_red(parent);
150 __rb_rotate_left(parent, root);
151 other = parent->rb_right;
152 }
153 if ((!other->rb_left || rb_is_black(other->rb_left)) &&
154 (!other->rb_right || rb_is_black(other->rb_right)))
155 {
156 rb_set_red(other);
157 node = parent;
158 parent = rb_parent(node);
159 }
160 else
161 {
162 if (!other->rb_right || rb_is_black(other->rb_right))
163 {
164 rb_set_black(other->rb_left);
165 rb_set_red(other);
166 __rb_rotate_right(other, root);
167 other = parent->rb_right;
168 }
169 rb_set_color(other, rb_color(parent));
170 rb_set_black(parent);
171 rb_set_black(other->rb_right);
172 __rb_rotate_left(parent, root);
173 node = root->rb_node;
174 break;
175 }
176 }
177 else
178 {
179 other = parent->rb_left;
180 if (rb_is_red(other))
181 {
182 rb_set_black(other);
183 rb_set_red(parent);
184 __rb_rotate_right(parent, root);
185 other = parent->rb_left;
186 }
187 if ((!other->rb_left || rb_is_black(other->rb_left)) &&
188 (!other->rb_right || rb_is_black(other->rb_right)))
189 {
190 rb_set_red(other);
191 node = parent;
192 parent = rb_parent(node);
193 }
194 else
195 {
196 if (!other->rb_left || rb_is_black(other->rb_left))
197 {
198 rb_set_black(other->rb_right);
199 rb_set_red(other);
200 __rb_rotate_left(other, root);
201 other = parent->rb_left;
202 }
203 rb_set_color(other, rb_color(parent));
204 rb_set_black(parent);
205 rb_set_black(other->rb_left);
206 __rb_rotate_right(parent, root);
207 node = root->rb_node;
208 break;
209 }
210 }
211 }
212 if (node)
213 rb_set_black(node);
214}
215
216void rb_erase(struct rb_node *node, struct rb_root *root)
217{
218 struct rb_node *child, *parent;
219 int color;
220
221 if (!node->rb_left)
222 child = node->rb_right;
223 else if (!node->rb_right)
224 child = node->rb_left;
225 else
226 {
227 struct rb_node *old = node, *left;
228
229 node = node->rb_right;
230 while ((left = node->rb_left) != NULL)
231 node = left;
232 child = node->rb_right;
233 parent = rb_parent(node);
234 color = rb_color(node);
235
236 if (child)
237 rb_set_parent(child, parent);
238 if (parent == old) {
239 parent->rb_right = child;
240 parent = node;
241 } else
242 parent->rb_left = child;
243
244 node->rb_parent_color = old->rb_parent_color;
245 node->rb_right = old->rb_right;
246 node->rb_left = old->rb_left;
247
248 if (rb_parent(old))
249 {
250 if (rb_parent(old)->rb_left == old)
251 rb_parent(old)->rb_left = node;
252 else
253 rb_parent(old)->rb_right = node;
254 } else
255 root->rb_node = node;
256
257 rb_set_parent(old->rb_left, node);
258 if (old->rb_right)
259 rb_set_parent(old->rb_right, node);
260 goto color;
261 }
262
263 parent = rb_parent(node);
264 color = rb_color(node);
265
266 if (child)
267 rb_set_parent(child, parent);
268 if (parent)
269 {
270 if (parent->rb_left == node)
271 parent->rb_left = child;
272 else
273 parent->rb_right = child;
274 }
275 else
276 root->rb_node = child;
277
278 color:
279 if (color == RB_BLACK)
280 __rb_erase_color(child, parent, root);
281}
282
283/*
284 * This function returns the first node (in sort order) of the tree.
285 */
286struct rb_node *rb_first(const struct rb_root *root)
287{
288 struct rb_node *n;
289
290 n = root->rb_node;
291 if (!n)
292 return NULL;
293 while (n->rb_left)
294 n = n->rb_left;
295 return n;
296}
297
298struct rb_node *rb_last(const struct rb_root *root)
299{
300 struct rb_node *n;
301
302 n = root->rb_node;
303 if (!n)
304 return NULL;
305 while (n->rb_right)
306 n = n->rb_right;
307 return n;
308}
309
310struct rb_node *rb_next(const struct rb_node *node)
311{
312 struct rb_node *parent;
313
314 if (rb_parent(node) == node)
315 return NULL;
316
317 /* If we have a right-hand child, go down and then left as far
318 as we can. */
319 if (node->rb_right) {
320 node = node->rb_right;
321 while (node->rb_left)
322 node=node->rb_left;
323 return (struct rb_node *)node;
324 }
325
326 /* No right-hand children. Everything down and left is
327 smaller than us, so any 'next' node must be in the general
328 direction of our parent. Go up the tree; any time the
329 ancestor is a right-hand child of its parent, keep going
330 up. First time it's a left-hand child of its parent, said
331 parent is our 'next' node. */
332 while ((parent = rb_parent(node)) && node == parent->rb_right)
333 node = parent;
334
335 return parent;
336}
337
338struct rb_node *rb_prev(const struct rb_node *node)
339{
340 struct rb_node *parent;
341
342 if (rb_parent(node) == node)
343 return NULL;
344
345 /* If we have a left-hand child, go down and then right as far
346 as we can. */
347 if (node->rb_left) {
348 node = node->rb_left;
349 while (node->rb_right)
350 node=node->rb_right;
351 return (struct rb_node *)node;
352 }
353
354 /* No left-hand children. Go up till we find an ancestor which
355 is a right-hand child of its parent */
356 while ((parent = rb_parent(node)) && node == parent->rb_left)
357 node = parent;
358
359 return parent;
360}
361
362void rb_replace_node(struct rb_node *victim, struct rb_node *new,
363 struct rb_root *root)
364{
365 struct rb_node *parent = rb_parent(victim);
366
367 /* Set the surrounding nodes to point to the replacement */
368 if (parent) {
369 if (victim == parent->rb_left)
370 parent->rb_left = new;
371 else
372 parent->rb_right = new;
373 } else {
374 root->rb_node = new;
375 }
376 if (victim->rb_left)
377 rb_set_parent(victim->rb_left, new);
378 if (victim->rb_right)
379 rb_set_parent(victim->rb_right, new);
380
381 /* Copy the pointers/colour from the victim to the replacement */
382 *new = *victim;
383}
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