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[fio.git] / 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 "rbtree.h"
24
25 static void __rb_rotate_left(struct rb_node *node, struct rb_root *root)
26 {
27         struct rb_node *right = node->rb_right;
28         struct rb_node *parent = rb_parent(node);
29
30         if ((node->rb_right = right->rb_left))
31                 rb_set_parent(right->rb_left, node);
32         right->rb_left = node;
33
34         rb_set_parent(right, parent);
35
36         if (parent)
37         {
38                 if (node == parent->rb_left)
39                         parent->rb_left = right;
40                 else
41                         parent->rb_right = right;
42         }
43         else
44                 root->rb_node = right;
45         rb_set_parent(node, right);
46 }
47
48 static void __rb_rotate_right(struct rb_node *node, struct rb_root *root)
49 {
50         struct rb_node *left = node->rb_left;
51         struct rb_node *parent = rb_parent(node);
52
53         if ((node->rb_left = left->rb_right))
54                 rb_set_parent(left->rb_right, node);
55         left->rb_right = node;
56
57         rb_set_parent(left, parent);
58
59         if (parent)
60         {
61                 if (node == parent->rb_right)
62                         parent->rb_right = left;
63                 else
64                         parent->rb_left = left;
65         }
66         else
67                 root->rb_node = left;
68         rb_set_parent(node, left);
69 }
70
71 void rb_insert_color(struct rb_node *node, struct rb_root *root)
72 {
73         struct rb_node *parent, *gparent;
74
75         while ((parent = rb_parent(node)) && rb_is_red(parent))
76         {
77                 gparent = rb_parent(parent);
78
79                 if (parent == gparent->rb_left)
80                 {
81                         {
82                                 register struct rb_node *uncle = gparent->rb_right;
83                                 if (uncle && rb_is_red(uncle))
84                                 {
85                                         rb_set_black(uncle);
86                                         rb_set_black(parent);
87                                         rb_set_red(gparent);
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
102                         rb_set_black(parent);
103                         rb_set_red(gparent);
104                         __rb_rotate_right(gparent, root);
105                 } else {
106                         {
107                                 register struct rb_node *uncle = gparent->rb_left;
108                                 if (uncle && rb_is_red(uncle))
109                                 {
110                                         rb_set_black(uncle);
111                                         rb_set_black(parent);
112                                         rb_set_red(gparent);
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
127                         rb_set_black(parent);
128                         rb_set_red(gparent);
129                         __rb_rotate_left(gparent, root);
130                 }
131         }
132
133         rb_set_black(root->rb_node);
134 }
135
136 static void __rb_erase_color(struct rb_node *node, struct rb_node *parent,
137                              struct rb_root *root)
138 {
139         struct rb_node *other;
140
141         while ((!node || rb_is_black(node)) && node != root->rb_node)
142         {
143                 if (parent->rb_left == node)
144                 {
145                         other = parent->rb_right;
146                         if (rb_is_red(other))
147                         {
148                                 rb_set_black(other);
149                                 rb_set_red(parent);
150                                 __rb_rotate_left(parent, root);
151                                 other = parent->rb_right;
152                         }
153                         if ((!other->rb_left || rb_is_black(other->rb_left)) &&
154                             (!other->rb_right || rb_is_black(other->rb_right)))
155                         {
156                                 rb_set_red(other);
157                                 node = parent;
158                                 parent = rb_parent(node);
159                         }
160                         else
161                         {
162                                 if (!other->rb_right || rb_is_black(other->rb_right))
163                                 {
164                                         struct rb_node *o_left;
165                                         if ((o_left = other->rb_left))
166                                                 rb_set_black(o_left);
167                                         rb_set_red(other);
168                                         __rb_rotate_right(other, root);
169                                         other = parent->rb_right;
170                                 }
171                                 rb_set_color(other, rb_color(parent));
172                                 rb_set_black(parent);
173                                 if (other->rb_right)
174                                         rb_set_black(other->rb_right);
175                                 __rb_rotate_left(parent, root);
176                                 node = root->rb_node;
177                                 break;
178                         }
179                 }
180                 else
181                 {
182                         other = parent->rb_left;
183                         if (rb_is_red(other))
184                         {
185                                 rb_set_black(other);
186                                 rb_set_red(parent);
187                                 __rb_rotate_right(parent, root);
188                                 other = parent->rb_left;
189                         }
190                         if ((!other->rb_left || rb_is_black(other->rb_left)) &&
191                             (!other->rb_right || rb_is_black(other->rb_right)))
192                         {
193                                 rb_set_red(other);
194                                 node = parent;
195                                 parent = rb_parent(node);
196                         }
197                         else
198                         {
199                                 if (!other->rb_left || rb_is_black(other->rb_left))
200                                 {
201                                         register struct rb_node *o_right;
202                                         if ((o_right = other->rb_right))
203                                                 rb_set_black(o_right);
204                                         rb_set_red(other);
205                                         __rb_rotate_left(other, root);
206                                         other = parent->rb_left;
207                                 }
208                                 rb_set_color(other, rb_color(parent));
209                                 rb_set_black(parent);
210                                 if (other->rb_left)
211                                         rb_set_black(other->rb_left);
212                                 __rb_rotate_right(parent, root);
213                                 node = root->rb_node;
214                                 break;
215                         }
216                 }
217         }
218         if (node)
219                 rb_set_black(node);
220 }
221
222 void 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;
239                 parent = rb_parent(node);
240                 color = rb_color(node);
241
242                 if (child)
243                         rb_set_parent(child, parent);
244                 if (parent == old) {
245                         parent->rb_right = child;
246                         parent = node;
247                 } else
248                         parent->rb_left = child;
249
250                 node->rb_parent_color = old->rb_parent_color;
251                 node->rb_right = old->rb_right;
252                 node->rb_left = old->rb_left;
253
254                 if (rb_parent(old))
255                 {
256                         if (rb_parent(old)->rb_left == old)
257                                 rb_parent(old)->rb_left = node;
258                         else
259                                 rb_parent(old)->rb_right = node;
260                 } else
261                         root->rb_node = node;
262
263                 rb_set_parent(old->rb_left, node);
264                 if (old->rb_right)
265                         rb_set_parent(old->rb_right, node);
266                 goto color;
267         }
268
269         parent = rb_parent(node);
270         color = rb_color(node);
271
272         if (child)
273                 rb_set_parent(child, parent);
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  */
292 struct 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 }