Merge commit 'v2.6.34.7' into dev-df3210-staging
[linux-2.6/parrot-frames.git] / lib / rbtree.c
blobe2aa3be29858cdcdd69bf4a43a67813db84079ee
1 /*
2 Red Black Trees
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
20 linux/lib/rbtree.c
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);
37 if (parent)
39 if (node == parent->rb_left)
40 parent->rb_left = right;
41 else
42 parent->rb_right = right;
44 else
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);
60 if (parent)
62 if (node == parent->rb_right)
63 parent->rb_right = left;
64 else
65 parent->rb_left = left;
67 else
68 root->rb_node = 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))
86 rb_set_black(uncle);
87 rb_set_black(parent);
88 rb_set_red(gparent);
89 node = gparent;
90 continue;
94 if (parent->rb_right == node)
96 register struct rb_node *tmp;
97 __rb_rotate_left(parent, root);
98 tmp = parent;
99 parent = node;
100 node = tmp;
103 rb_set_black(parent);
104 rb_set_red(gparent);
105 __rb_rotate_right(gparent, root);
106 } else {
108 register struct rb_node *uncle = gparent->rb_left;
109 if (uncle && rb_is_red(uncle))
111 rb_set_black(uncle);
112 rb_set_black(parent);
113 rb_set_red(gparent);
114 node = gparent;
115 continue;
119 if (parent->rb_left == node)
121 register struct rb_node *tmp;
122 __rb_rotate_right(parent, root);
123 tmp = parent;
124 parent = node;
125 node = tmp;
128 rb_set_black(parent);
129 rb_set_red(gparent);
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))
150 rb_set_black(other);
151 rb_set_red(parent);
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)))
158 rb_set_red(other);
159 node = parent;
160 parent = rb_parent(node);
162 else
164 if (!other->rb_right || rb_is_black(other->rb_right))
166 rb_set_black(other->rb_left);
167 rb_set_red(other);
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;
176 break;
179 else
181 other = parent->rb_left;
182 if (rb_is_red(other))
184 rb_set_black(other);
185 rb_set_red(parent);
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)))
192 rb_set_red(other);
193 node = parent;
194 parent = rb_parent(node);
196 else
198 if (!other->rb_left || rb_is_black(other->rb_left))
200 rb_set_black(other->rb_right);
201 rb_set_red(other);
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;
210 break;
214 if (node)
215 rb_set_black(node);
218 void rb_erase(struct rb_node *node, struct rb_root *root)
220 struct rb_node *child, *parent;
221 int color;
223 if (!node->rb_left)
224 child = node->rb_right;
225 else if (!node->rb_right)
226 child = node->rb_left;
227 else
229 struct rb_node *old = node, *left;
231 node = node->rb_right;
232 while ((left = node->rb_left) != NULL)
233 node = left;
235 if (rb_parent(old)) {
236 if (rb_parent(old)->rb_left == old)
237 rb_parent(old)->rb_left = node;
238 else
239 rb_parent(old)->rb_right = node;
240 } else
241 root->rb_node = node;
243 child = node->rb_right;
244 parent = rb_parent(node);
245 color = rb_color(node);
247 if (parent == old) {
248 parent = node;
249 } else {
250 if (child)
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);
262 goto color;
265 parent = rb_parent(node);
266 color = rb_color(node);
268 if (child)
269 rb_set_parent(child, parent);
270 if (parent)
272 if (parent->rb_left == node)
273 parent->rb_left = child;
274 else
275 parent->rb_right = child;
277 else
278 root->rb_node = child;
280 color:
281 if (color == RB_BLACK)
282 __rb_erase_color(child, parent, root);
284 EXPORT_SYMBOL(rb_erase);
287 * This function returns the first node (in sort order) of the tree.
289 struct rb_node *rb_first(const struct rb_root *root)
291 struct rb_node *n;
293 n = root->rb_node;
294 if (!n)
295 return NULL;
296 while (n->rb_left)
297 n = n->rb_left;
298 return n;
300 EXPORT_SYMBOL(rb_first);
302 struct rb_node *rb_last(const struct rb_root *root)
304 struct rb_node *n;
306 n = root->rb_node;
307 if (!n)
308 return NULL;
309 while (n->rb_right)
310 n = n->rb_right;
311 return n;
313 EXPORT_SYMBOL(rb_last);
315 struct rb_node *rb_next(const struct rb_node *node)
317 struct rb_node *parent;
319 if (rb_parent(node) == node)
320 return NULL;
322 /* If we have a right-hand child, go down and then left as far
323 as we can. */
324 if (node->rb_right) {
325 node = node->rb_right;
326 while (node->rb_left)
327 node=node->rb_left;
328 return (struct rb_node *)node;
331 /* No right-hand children. Everything down and left is
332 smaller than us, so any 'next' node must be in the general
333 direction of our parent. Go up the tree; any time the
334 ancestor is a right-hand child of its parent, keep going
335 up. First time it's a left-hand child of its parent, said
336 parent is our 'next' node. */
337 while ((parent = rb_parent(node)) && node == parent->rb_right)
338 node = parent;
340 return parent;
342 EXPORT_SYMBOL(rb_next);
344 struct rb_node *rb_prev(const struct rb_node *node)
346 struct rb_node *parent;
348 if (rb_parent(node) == node)
349 return NULL;
351 /* If we have a left-hand child, go down and then right as far
352 as we can. */
353 if (node->rb_left) {
354 node = node->rb_left;
355 while (node->rb_right)
356 node=node->rb_right;
357 return (struct rb_node *)node;
360 /* No left-hand children. Go up till we find an ancestor which
361 is a right-hand child of its parent */
362 while ((parent = rb_parent(node)) && node == parent->rb_left)
363 node = parent;
365 return parent;
367 EXPORT_SYMBOL(rb_prev);
369 void rb_replace_node(struct rb_node *victim, struct rb_node *new,
370 struct rb_root *root)
372 struct rb_node *parent = rb_parent(victim);
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;
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);
388 /* Copy the pointers/colour from the victim to the replacement */
389 *new = *victim;
391 EXPORT_SYMBOL(rb_replace_node);