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[fio.git] / rbtree.c
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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;
44b5374f 28 struct rb_node *parent = rb_parent(node);
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29
30 if ((node->rb_right = right->rb_left))
44b5374f 31 rb_set_parent(right->rb_left, node);
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32 right->rb_left = node;
33
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34 rb_set_parent(right, parent);
35
36 if (parent)
4b87898e 37 {
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38 if (node == parent->rb_left)
39 parent->rb_left = right;
4b87898e 40 else
44b5374f 41 parent->rb_right = right;
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42 }
43 else
44 root->rb_node = right;
44b5374f 45 rb_set_parent(node, right);
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46}
47
48static void __rb_rotate_right(struct rb_node *node, struct rb_root *root)
49{
50 struct rb_node *left = node->rb_left;
44b5374f 51 struct rb_node *parent = rb_parent(node);
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52
53 if ((node->rb_left = left->rb_right))
44b5374f 54 rb_set_parent(left->rb_right, node);
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55 left->rb_right = node;
56
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57 rb_set_parent(left, parent);
58
59 if (parent)
4b87898e 60 {
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61 if (node == parent->rb_right)
62 parent->rb_right = left;
4b87898e 63 else
44b5374f 64 parent->rb_left = left;
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65 }
66 else
67 root->rb_node = left;
44b5374f 68 rb_set_parent(node, left);
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69}
70
71void rb_insert_color(struct rb_node *node, struct rb_root *root)
72{
73 struct rb_node *parent, *gparent;
74
44b5374f 75 while ((parent = rb_parent(node)) && rb_is_red(parent))
4b87898e 76 {
44b5374f 77 gparent = rb_parent(parent);
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78
79 if (parent == gparent->rb_left)
80 {
81 {
82 register struct rb_node *uncle = gparent->rb_right;
44b5374f 83 if (uncle && rb_is_red(uncle))
4b87898e 84 {
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85 rb_set_black(uncle);
86 rb_set_black(parent);
87 rb_set_red(gparent);
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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
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102 rb_set_black(parent);
103 rb_set_red(gparent);
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104 __rb_rotate_right(gparent, root);
105 } else {
106 {
107 register struct rb_node *uncle = gparent->rb_left;
44b5374f 108 if (uncle && rb_is_red(uncle))
4b87898e 109 {
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110 rb_set_black(uncle);
111 rb_set_black(parent);
112 rb_set_red(gparent);
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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
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127 rb_set_black(parent);
128 rb_set_red(gparent);
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129 __rb_rotate_left(gparent, root);
130 }
131 }
132
44b5374f 133 rb_set_black(root->rb_node);
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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
44b5374f 141 while ((!node || rb_is_black(node)) && node != root->rb_node)
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142 {
143 if (parent->rb_left == node)
144 {
145 other = parent->rb_right;
44b5374f 146 if (rb_is_red(other))
4b87898e 147 {
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148 rb_set_black(other);
149 rb_set_red(parent);
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150 __rb_rotate_left(parent, root);
151 other = parent->rb_right;
152 }
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153 if ((!other->rb_left || rb_is_black(other->rb_left)) &&
154 (!other->rb_right || rb_is_black(other->rb_right)))
4b87898e 155 {
44b5374f 156 rb_set_red(other);
4b87898e 157 node = parent;
44b5374f 158 parent = rb_parent(node);
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159 }
160 else
161 {
44b5374f 162 if (!other->rb_right || rb_is_black(other->rb_right))
4b87898e 163 {
44b5374f 164 struct rb_node *o_left;
4b87898e 165 if ((o_left = other->rb_left))
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166 rb_set_black(o_left);
167 rb_set_red(other);
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168 __rb_rotate_right(other, root);
169 other = parent->rb_right;
170 }
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171 rb_set_color(other, rb_color(parent));
172 rb_set_black(parent);
4b87898e 173 if (other->rb_right)
44b5374f 174 rb_set_black(other->rb_right);
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175 __rb_rotate_left(parent, root);
176 node = root->rb_node;
177 break;
178 }
179 }
180 else
181 {
182 other = parent->rb_left;
44b5374f 183 if (rb_is_red(other))
4b87898e 184 {
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185 rb_set_black(other);
186 rb_set_red(parent);
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187 __rb_rotate_right(parent, root);
188 other = parent->rb_left;
189 }
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190 if ((!other->rb_left || rb_is_black(other->rb_left)) &&
191 (!other->rb_right || rb_is_black(other->rb_right)))
4b87898e 192 {
44b5374f 193 rb_set_red(other);
4b87898e 194 node = parent;
44b5374f 195 parent = rb_parent(node);
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196 }
197 else
198 {
44b5374f 199 if (!other->rb_left || rb_is_black(other->rb_left))
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200 {
201 register struct rb_node *o_right;
202 if ((o_right = other->rb_right))
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203 rb_set_black(o_right);
204 rb_set_red(other);
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205 __rb_rotate_left(other, root);
206 other = parent->rb_left;
207 }
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208 rb_set_color(other, rb_color(parent));
209 rb_set_black(parent);
4b87898e 210 if (other->rb_left)
44b5374f 211 rb_set_black(other->rb_left);
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212 __rb_rotate_right(parent, root);
213 node = root->rb_node;
214 break;
215 }
216 }
217 }
218 if (node)
44b5374f 219 rb_set_black(node);
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220}
221
222void rb_erase(struct rb_node *node, struct rb_root *root)
223{
224 struct rb_node *child, *parent;
225 int color;
226
227 if (!node->rb_left)
228 child = node->rb_right;
229 else if (!node->rb_right)
230 child = node->rb_left;
231 else
232 {
233 struct rb_node *old = node, *left;
234
235 node = node->rb_right;
236 while ((left = node->rb_left) != NULL)
237 node = left;
238 child = node->rb_right;
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239 parent = rb_parent(node);
240 color = rb_color(node);
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241
242 if (child)
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243 rb_set_parent(child, parent);
244 if (parent == old) {
245 parent->rb_right = child;
4b87898e 246 parent = node;
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247 } else
248 parent->rb_left = child;
249
250 node->rb_parent_color = old->rb_parent_color;
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251 node->rb_right = old->rb_right;
252 node->rb_left = old->rb_left;
253
44b5374f 254 if (rb_parent(old))
4b87898e 255 {
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256 if (rb_parent(old)->rb_left == old)
257 rb_parent(old)->rb_left = node;
4b87898e 258 else
44b5374f 259 rb_parent(old)->rb_right = node;
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260 } else
261 root->rb_node = node;
262
44b5374f 263 rb_set_parent(old->rb_left, node);
4b87898e 264 if (old->rb_right)
44b5374f 265 rb_set_parent(old->rb_right, node);
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266 goto color;
267 }
268
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269 parent = rb_parent(node);
270 color = rb_color(node);
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271
272 if (child)
44b5374f 273 rb_set_parent(child, parent);
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274 if (parent)
275 {
276 if (parent->rb_left == node)
277 parent->rb_left = child;
278 else
279 parent->rb_right = child;
280 }
281 else
282 root->rb_node = child;
283
284 color:
285 if (color == RB_BLACK)
286 __rb_erase_color(child, parent, root);
287}
288
289/*
290 * This function returns the first node (in sort order) of the tree.
291 */
292struct rb_node *rb_first(struct rb_root *root)
293{
294 struct rb_node *n;
295
296 n = root->rb_node;
297 if (!n)
298 return NULL;
299 while (n->rb_left)
300 n = n->rb_left;
301 return n;
302}