x86: fix __cpuinit/__init tangle in init_thread_xstate()
[linux-2.6.git] / lib / rbtree.c
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>
24 #include <linux/module.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 EXPORT_SYMBOL(rb_insert_color);
137
138 static void __rb_erase_color(struct rb_node *node, struct rb_node *parent,
139                              struct rb_root *root)
140 {
141         struct rb_node *other;
142
143         while ((!node || rb_is_black(node)) && node != root->rb_node)
144         {
145                 if (parent->rb_left == node)
146                 {
147                         other = parent->rb_right;
148                         if (rb_is_red(other))
149                         {
150                                 rb_set_black(other);
151                                 rb_set_red(parent);
152                                 __rb_rotate_left(parent, root);
153                                 other = parent->rb_right;
154                         }
155                         if ((!other->rb_left || rb_is_black(other->rb_left)) &&
156                             (!other->rb_right || rb_is_black(other->rb_right)))
157                         {
158                                 rb_set_red(other);
159                                 node = parent;
160                                 parent = rb_parent(node);
161                         }
162                         else
163                         {
164                                 if (!other->rb_right || rb_is_black(other->rb_right))
165                                 {
166                                         struct rb_node *o_left;
167                                         if ((o_left = other->rb_left))
168                                                 rb_set_black(o_left);
169                                         rb_set_red(other);
170                                         __rb_rotate_right(other, root);
171                                         other = parent->rb_right;
172                                 }
173                                 rb_set_color(other, rb_color(parent));
174                                 rb_set_black(parent);
175                                 if (other->rb_right)
176                                         rb_set_black(other->rb_right);
177                                 __rb_rotate_left(parent, root);
178                                 node = root->rb_node;
179                                 break;
180                         }
181                 }
182                 else
183                 {
184                         other = parent->rb_left;
185                         if (rb_is_red(other))
186                         {
187                                 rb_set_black(other);
188                                 rb_set_red(parent);
189                                 __rb_rotate_right(parent, root);
190                                 other = parent->rb_left;
191                         }
192                         if ((!other->rb_left || rb_is_black(other->rb_left)) &&
193                             (!other->rb_right || rb_is_black(other->rb_right)))
194                         {
195                                 rb_set_red(other);
196                                 node = parent;
197                                 parent = rb_parent(node);
198                         }
199                         else
200                         {
201                                 if (!other->rb_left || rb_is_black(other->rb_left))
202                                 {
203                                         register struct rb_node *o_right;
204                                         if ((o_right = other->rb_right))
205                                                 rb_set_black(o_right);
206                                         rb_set_red(other);
207                                         __rb_rotate_left(other, root);
208                                         other = parent->rb_left;
209                                 }
210                                 rb_set_color(other, rb_color(parent));
211                                 rb_set_black(parent);
212                                 if (other->rb_left)
213                                         rb_set_black(other->rb_left);
214                                 __rb_rotate_right(parent, root);
215                                 node = root->rb_node;
216                                 break;
217                         }
218                 }
219         }
220         if (node)
221                 rb_set_black(node);
222 }
223
224 void rb_erase(struct rb_node *node, struct rb_root *root)
225 {
226         struct rb_node *child, *parent;
227         int color;
228
229         if (!node->rb_left)
230                 child = node->rb_right;
231         else if (!node->rb_right)
232                 child = node->rb_left;
233         else
234         {
235                 struct rb_node *old = node, *left;
236
237                 node = node->rb_right;
238                 while ((left = node->rb_left) != NULL)
239                         node = left;
240                 child = node->rb_right;
241                 parent = rb_parent(node);
242                 color = rb_color(node);
243
244                 if (child)
245                         rb_set_parent(child, parent);
246                 if (parent == old) {
247                         parent->rb_right = child;
248                         parent = node;
249                 } else
250                         parent->rb_left = child;
251
252                 node->rb_parent_color = old->rb_parent_color;
253                 node->rb_right = old->rb_right;
254                 node->rb_left = old->rb_left;
255
256                 if (rb_parent(old))
257                 {
258                         if (rb_parent(old)->rb_left == old)
259                                 rb_parent(old)->rb_left = node;
260                         else
261                                 rb_parent(old)->rb_right = node;
262                 } else
263                         root->rb_node = node;
264
265                 rb_set_parent(old->rb_left, node);
266                 if (old->rb_right)
267                         rb_set_parent(old->rb_right, node);
268                 goto color;
269         }
270
271         parent = rb_parent(node);
272         color = rb_color(node);
273
274         if (child)
275                 rb_set_parent(child, parent);
276         if (parent)
277         {
278                 if (parent->rb_left == node)
279                         parent->rb_left = child;
280                 else
281                         parent->rb_right = child;
282         }
283         else
284                 root->rb_node = child;
285
286  color:
287         if (color == RB_BLACK)
288                 __rb_erase_color(child, parent, root);
289 }
290 EXPORT_SYMBOL(rb_erase);
291
292 /*
293  * This function returns the first node (in sort order) of the tree.
294  */
295 struct rb_node *rb_first(struct rb_root *root)
296 {
297         struct rb_node  *n;
298
299         n = root->rb_node;
300         if (!n)
301                 return NULL;
302         while (n->rb_left)
303                 n = n->rb_left;
304         return n;
305 }
306 EXPORT_SYMBOL(rb_first);
307
308 struct rb_node *rb_last(struct rb_root *root)
309 {
310         struct rb_node  *n;
311
312         n = root->rb_node;
313         if (!n)
314                 return NULL;
315         while (n->rb_right)
316                 n = n->rb_right;
317         return n;
318 }
319 EXPORT_SYMBOL(rb_last);
320
321 struct rb_node *rb_next(struct rb_node *node)
322 {
323         struct rb_node *parent;
324
325         if (rb_parent(node) == node)
326                 return NULL;
327
328         /* If we have a right-hand child, go down and then left as far
329            as we can. */
330         if (node->rb_right) {
331                 node = node->rb_right; 
332                 while (node->rb_left)
333                         node=node->rb_left;
334                 return node;
335         }
336
337         /* No right-hand children.  Everything down and left is
338            smaller than us, so any 'next' node must be in the general
339            direction of our parent. Go up the tree; any time the
340            ancestor is a right-hand child of its parent, keep going
341            up. First time it's a left-hand child of its parent, said
342            parent is our 'next' node. */
343         while ((parent = rb_parent(node)) && node == parent->rb_right)
344                 node = parent;
345
346         return parent;
347 }
348 EXPORT_SYMBOL(rb_next);
349
350 struct rb_node *rb_prev(struct rb_node *node)
351 {
352         struct rb_node *parent;
353
354         if (rb_parent(node) == node)
355                 return NULL;
356
357         /* If we have a left-hand child, go down and then right as far
358            as we can. */
359         if (node->rb_left) {
360                 node = node->rb_left; 
361                 while (node->rb_right)
362                         node=node->rb_right;
363                 return node;
364         }
365
366         /* No left-hand children. Go up till we find an ancestor which
367            is a right-hand child of its parent */
368         while ((parent = rb_parent(node)) && node == parent->rb_left)
369                 node = parent;
370
371         return parent;
372 }
373 EXPORT_SYMBOL(rb_prev);
374
375 void rb_replace_node(struct rb_node *victim, struct rb_node *new,
376                      struct rb_root *root)
377 {
378         struct rb_node *parent = rb_parent(victim);
379
380         /* Set the surrounding nodes to point to the replacement */
381         if (parent) {
382                 if (victim == parent->rb_left)
383                         parent->rb_left = new;
384                 else
385                         parent->rb_right = new;
386         } else {
387                 root->rb_node = new;
388         }
389         if (victim->rb_left)
390                 rb_set_parent(victim->rb_left, new);
391         if (victim->rb_right)
392                 rb_set_parent(victim->rb_right, new);
393
394         /* Copy the pointers/colour from the victim to the replacement */
395         *new = *victim;
396 }
397 EXPORT_SYMBOL(rb_replace_node);