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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 <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 }