tree.c
Go to the documentation of this file.
1 /*
2  * copyright (c) 2006 Michael Niedermayer <michaelni@gmx.at>
3  *
4  * This file is part of Libav.
5  *
6  * Libav is free software; you can redistribute it and/or
7  * modify it under the terms of the GNU Lesser General Public
8  * License as published by the Free Software Foundation; either
9  * version 2.1 of the License, or (at your option) any later version.
10  *
11  * Libav 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 GNU
14  * Lesser General Public License for more details.
15  *
16  * You should have received a copy of the GNU Lesser General Public
17  * License along with Libav; if not, write to the Free Software
18  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
19  */
20 
21 #include "log.h"
22 #include "tree.h"
23 
24 typedef struct AVTreeNode {
25  struct AVTreeNode *child[2];
26  void *elem;
27  int state;
28 } AVTreeNode;
29 
30 const int av_tree_node_size = sizeof(AVTreeNode);
31 
32 void *av_tree_find(const AVTreeNode *t, void *key,
33  int (*cmp)(void *key, const void *b), void *next[2])
34 {
35  if (t) {
36  unsigned int v = cmp(key, t->elem);
37  if (v) {
38  if (next) next[v >> 31] = t->elem;
39  return av_tree_find(t->child[(v >> 31) ^ 1], key, cmp, next);
40  } else {
41  if (next) {
42  av_tree_find(t->child[0], key, cmp, next);
43  av_tree_find(t->child[1], key, cmp, next);
44  }
45  return t->elem;
46  }
47  }
48  return NULL;
49 }
50 
51 void *av_tree_insert(AVTreeNode **tp, void *key,
52  int (*cmp)(void *key, const void *b), AVTreeNode **next)
53 {
54  AVTreeNode *t = *tp;
55  if (t) {
56  unsigned int v = cmp(t->elem, key);
57  void *ret;
58  if (!v) {
59  if (*next)
60  return t->elem;
61  else if (t->child[0] || t->child[1]) {
62  int i = !t->child[0];
63  void *next_elem[2];
64  av_tree_find(t->child[i], key, cmp, next_elem);
65  key = t->elem = next_elem[i];
66  v = -i;
67  } else {
68  *next = t;
69  *tp = NULL;
70  return NULL;
71  }
72  }
73  ret = av_tree_insert(&t->child[v >> 31], key, cmp, next);
74  if (!ret) {
75  int i = (v >> 31) ^ !!*next;
76  AVTreeNode **child = &t->child[i];
77  t->state += 2 * i - 1;
78 
79  if (!(t->state & 1)) {
80  if (t->state) {
81  /* The following code is equivalent to
82  if((*child)->state*2 == -t->state)
83  rotate(child, i^1);
84  rotate(tp, i);
85 
86  with rotate():
87  static void rotate(AVTreeNode **tp, int i) {
88  AVTreeNode *t= *tp;
89 
90  *tp= t->child[i];
91  t->child[i]= t->child[i]->child[i^1];
92  (*tp)->child[i^1]= t;
93  i= 4*t->state + 2*(*tp)->state + 12;
94  t ->state= ((0x614586 >> i) & 3)-1;
95  (*tp)->state= ((*tp)->state>>1) + ((0x400EEA >> i) & 3)-1;
96  }
97  but such a rotate function is both bigger and slower
98  */
99  if (( *child )->state * 2 == -t->state) {
100  *tp = (*child)->child[i ^ 1];
101  (*child)->child[i ^ 1] = (*tp)->child[i];
102  (*tp)->child[i] = *child;
103  *child = ( *tp )->child[i ^ 1];
104  (*tp)->child[i ^ 1] = t;
105 
106  (*tp)->child[0]->state = -((*tp)->state > 0);
107  (*tp)->child[1]->state = (*tp)->state < 0;
108  (*tp)->state = 0;
109  } else {
110  *tp = *child;
111  *child = (*child)->child[i ^ 1];
112  (*tp)->child[i ^ 1] = t;
113  if ((*tp)->state) t->state = 0;
114  else t->state >>= 1;
115  (*tp)->state = -t->state;
116  }
117  }
118  }
119  if (!(*tp)->state ^ !!*next)
120  return key;
121  }
122  return ret;
123  } else {
124  *tp = *next;
125  *next = NULL;
126  if (*tp) {
127  (*tp)->elem = key;
128  return NULL;
129  } else
130  return key;
131  }
132 }
133 
135 {
136  if (t) {
137  av_tree_destroy(t->child[0]);
138  av_tree_destroy(t->child[1]);
139  av_free(t);
140  }
141 }
142 
143 void av_tree_enumerate(AVTreeNode *t, void *opaque,
144  int (*cmp)(void *opaque, void *elem),
145  int (*enu)(void *opaque, void *elem))
146 {
147  if (t) {
148  int v = cmp ? cmp(opaque, t->elem) : 0;
149  if (v >= 0)
150  av_tree_enumerate(t->child[0], opaque, cmp, enu);
151  if (v == 0)
152  enu(opaque, t->elem);
153  if (v <= 0)
154  av_tree_enumerate(t->child[1], opaque, cmp, enu);
155  }
156 }
157 
158 #ifdef TEST
159 
160 #include "lfg.h"
161 
162 static int check(AVTreeNode *t)
163 {
164  if (t) {
165  int left = check(t->child[0]);
166  int right = check(t->child[1]);
167 
168  if (left>999 || right>999)
169  return 1000;
170  if (right - left != t->state)
171  return 1000;
172  if (t->state>1 || t->state<-1)
173  return 1000;
174  return FFMAX(left, right) + 1;
175  }
176  return 0;
177 }
178 
179 static void print(AVTreeNode *t, int depth)
180 {
181  int i;
182  for (i = 0; i < depth * 4; i++) av_log(NULL, AV_LOG_ERROR, " ");
183  if (t) {
184  av_log(NULL, AV_LOG_ERROR, "Node %p %2d %p\n", t, t->state, t->elem);
185  print(t->child[0], depth + 1);
186  print(t->child[1], depth + 1);
187  } else
188  av_log(NULL, AV_LOG_ERROR, "NULL\n");
189 }
190 
191 static int cmp(void *a, const void *b)
192 {
193  return (uint8_t *) a - (const uint8_t *) b;
194 }
195 
196 int main (void)
197 {
198  int i;
199  void *k;
200  AVTreeNode *root = NULL, *node = NULL;
201  AVLFG prng;
202 
203  av_lfg_init(&prng, 1);
204 
205  for (i = 0; i < 10000; i++) {
206  int j = av_lfg_get(&prng) % 86294;
207  if (check(root) > 999) {
208  av_log(NULL, AV_LOG_ERROR, "FATAL error %d\n", i);
209  print(root, 0);
210  return -1;
211  }
212  av_log(NULL, AV_LOG_ERROR, "inserting %4d\n", j);
213  if (!node)
215  av_tree_insert(&root, (void *) (j + 1), cmp, &node);
216 
217  j = av_lfg_get(&prng) % 86294;
218  {
219  AVTreeNode *node2 = NULL;
220  av_log(NULL, AV_LOG_ERROR, "removing %4d\n", j);
221  av_tree_insert(&root, (void *) (j + 1), cmp, &node2);
222  k = av_tree_find(root, (void *) (j + 1), cmp, NULL);
223  if (k)
224  av_log(NULL, AV_LOG_ERROR, "removal failure %d\n", i);
225  }
226  }
227  return 0;
228 }
229 #endif