3 (C) 1999 Andrea Arcangeli <andrea@suse.de>
4 (C) 2002 David Woodhouse <dwmw2@infradead.org>
5 (C) 2007 Andre Noll <maan@systemlinux.org>
7 This program is free software; you can redistribute it and/or modify
8 it under the terms of the GNU General Public License as published by
9 the Free Software Foundation; either version 2 of the License, or
10 (at your option) any later version.
12 This program is distributed in the hope that it will be useful,
13 but WITHOUT ANY WARRANTY; without even the implied warranty of
14 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
15 GNU General Public License for more details.
17 You should have received a copy of the GNU General Public License
18 along with this program; if not, write to the Free Software
19 Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
27 static void __rb_rotate_left(struct rb_node *node, struct rb_root *root)
29 struct rb_node *right = node->rb_right;
30 struct rb_node *parent = rb_parent(node);
32 if ((node->rb_right = right->rb_left))
33 rb_set_parent(right->rb_left, node);
34 right->rb_left = node;
36 rb_set_parent(right, parent);
40 if (node == parent->rb_left)
41 parent->rb_left = right;
43 parent->rb_right = right;
46 root->rb_node = right;
47 rb_set_parent(node, right);
48 right->size = node->size;
51 node->size += node->rb_right->size;
53 node->size += node->rb_left->size;
56 static void __rb_rotate_right(struct rb_node *node, struct rb_root *root)
58 struct rb_node *left = node->rb_left;
59 struct rb_node *parent = rb_parent(node);
61 if ((node->rb_left = left->rb_right))
62 rb_set_parent(left->rb_right, node);
63 left->rb_right = node;
65 rb_set_parent(left, parent);
69 if (node == parent->rb_right)
70 parent->rb_right = left;
72 parent->rb_left = left;
76 rb_set_parent(node, left);
77 left->size = node->size;
80 node->size += node->rb_right->size;
82 node->size += node->rb_left->size;
85 void rb_insert_color(struct rb_node *node, struct rb_root *root)
87 struct rb_node *parent, *gparent;
89 while ((parent = rb_parent(node)) && rb_is_red(parent))
91 gparent = rb_parent(parent);
93 if (parent == gparent->rb_left)
96 register struct rb_node *uncle = gparent->rb_right;
97 if (uncle && rb_is_red(uncle))
100 rb_set_black(parent);
107 if (parent->rb_right == node)
109 register struct rb_node *tmp;
110 __rb_rotate_left(parent, root);
116 rb_set_black(parent);
118 __rb_rotate_right(gparent, root);
121 register struct rb_node *uncle = gparent->rb_left;
122 if (uncle && rb_is_red(uncle))
125 rb_set_black(parent);
132 if (parent->rb_left == node)
134 register struct rb_node *tmp;
135 __rb_rotate_right(parent, root);
141 rb_set_black(parent);
143 __rb_rotate_left(gparent, root);
147 rb_set_black(root->rb_node);
150 static void __rb_erase_color(struct rb_node *node, struct rb_node *parent,
151 struct rb_root *root)
153 struct rb_node *other;
155 while ((!node || rb_is_black(node)) && node != root->rb_node)
157 if (parent->rb_left == node)
159 other = parent->rb_right;
160 if (rb_is_red(other))
164 __rb_rotate_left(parent, root);
165 other = parent->rb_right;
167 if ((!other->rb_left || rb_is_black(other->rb_left)) &&
168 (!other->rb_right || rb_is_black(other->rb_right)))
172 parent = rb_parent(node);
176 if (!other->rb_right || rb_is_black(other->rb_right))
178 struct rb_node *o_left;
179 if ((o_left = other->rb_left))
180 rb_set_black(o_left);
182 __rb_rotate_right(other, root);
183 other = parent->rb_right;
185 rb_set_color(other, rb_color(parent));
186 rb_set_black(parent);
188 rb_set_black(other->rb_right);
189 __rb_rotate_left(parent, root);
190 node = root->rb_node;
196 other = parent->rb_left;
197 if (rb_is_red(other))
201 __rb_rotate_right(parent, root);
202 other = parent->rb_left;
204 if ((!other->rb_left || rb_is_black(other->rb_left)) &&
205 (!other->rb_right || rb_is_black(other->rb_right)))
209 parent = rb_parent(node);
213 if (!other->rb_left || rb_is_black(other->rb_left))
215 register struct rb_node *o_right;
216 if ((o_right = other->rb_right))
217 rb_set_black(o_right);
219 __rb_rotate_left(other, root);
220 other = parent->rb_left;
222 rb_set_color(other, rb_color(parent));
223 rb_set_black(parent);
225 rb_set_black(other->rb_left);
226 __rb_rotate_right(parent, root);
227 node = root->rb_node;
236 void rb_erase(struct rb_node *node, struct rb_root *root)
238 struct rb_node *child, *parent;
242 child = node->rb_right;
243 else if (!node->rb_right)
244 child = node->rb_left;
247 struct rb_node *old = node, *left;
249 node = node->rb_right;
250 while ((left = node->rb_left) != NULL)
252 child = node->rb_right;
253 parent = rb_parent(node);
254 color = rb_color(node);
257 rb_set_parent(child, parent);
259 parent->rb_right = child;
262 parent->rb_left = child;
264 node->rb_parent_color = old->rb_parent_color;
265 node->rb_right = old->rb_right;
266 node->rb_left = old->rb_left;
267 node->size = old->size;
271 if (rb_parent(old)->rb_left == old)
272 rb_parent(old)->rb_left = node;
274 rb_parent(old)->rb_right = node;
276 root->rb_node = node;
278 rb_set_parent(old->rb_left, node);
280 rb_set_parent(old->rb_right, node);
284 parent = rb_parent(node);
285 color = rb_color(node);
288 rb_set_parent(child, parent);
291 if (parent->rb_left == node)
292 parent->rb_left = child;
294 parent->rb_right = child;
297 root->rb_node = child;
300 if (color == RB_BLACK)
301 __rb_erase_color(child, parent, root);
305 * This function returns the first node (in sort order) of the tree.
307 struct rb_node *rb_first(struct rb_root *root)
319 struct rb_node *rb_last(struct rb_root *root)
331 struct rb_node *rb_next(struct rb_node *node)
333 struct rb_node *parent;
335 if (rb_parent(node) == node)
338 /* If we have a right-hand child, go down and then left as far
340 if (node->rb_right) {
341 node = node->rb_right;
342 while (node->rb_left)
347 /* No right-hand children. Everything down and left is
348 smaller than us, so any 'next' node must be in the general
349 direction of our parent. Go up the tree; any time the
350 ancestor is a right-hand child of its parent, keep going
351 up. First time it's a left-hand child of its parent, said
352 parent is our 'next' node. */
353 while ((parent = rb_parent(node)) && node == parent->rb_right)
359 struct rb_node *rb_prev(struct rb_node *node)
361 struct rb_node *parent;
363 if (rb_parent(node) == node)
366 /* If we have a left-hand child, go down and then right as far
369 node = node->rb_left;
370 while (node->rb_right)
375 /* No left-hand children. Go up till we find an ancestor which
376 is a right-hand child of its parent */
377 while ((parent = rb_parent(node)) && node == parent->rb_left)
383 void rb_replace_node(struct rb_node *victim, struct rb_node *new,
384 struct rb_root *root)
386 struct rb_node *parent = rb_parent(victim);
388 /* Set the surrounding nodes to point to the replacement */
390 if (victim == parent->rb_left)
391 parent->rb_left = new;
393 parent->rb_right = new;
398 rb_set_parent(victim->rb_left, new);
399 if (victim->rb_right)
400 rb_set_parent(victim->rb_right, new);
402 /* Copy the pointers/colour from the victim to the replacement */
407 * Get the n-th node (in sort order) of the tree.
409 * \param node The root of the subtree to consider.
410 * \param n The order statistic to compute.
412 * \return Pointer to the \a n th greatest node on success, \p NULL on errors.
414 struct rb_node *rb_nth(struct rb_node *node, unsigned n)
421 size += node->rb_left->size;
425 return rb_nth(node->rb_left, n);
426 return rb_nth(node->rb_right, n - size);
430 * Get the rank of a node in O(log n) time.
432 * \param node The node to get the rank of.
433 * \param rank Result pointer.
435 * \return Positive on success, -1 on errors.
437 int rb_rank(struct rb_node *node, unsigned *rank)
440 struct rb_node *parent;
445 *rank += node->rb_left->size;
446 while ((parent = rb_parent(node))) {
447 if (node == parent->rb_right) {
450 *rank += parent->rb_left->size;