tree.c
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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 "mem.h"
23 #include "tree.h"
24 
25 typedef struct AVTreeNode {
26  struct AVTreeNode *child[2];
27  void *elem;
28  int state;
29 } AVTreeNode;
30 
31 #if FF_API_CONTEXT_SIZE
32 const int av_tree_node_size = sizeof(AVTreeNode);
33 #endif
34 
36 {
37  return av_mallocz(sizeof(struct AVTreeNode));
38 }
39 
40 void *av_tree_find(const AVTreeNode *t, void *key,
41  int (*cmp)(void *key, const void *b), void *next[2])
42 {
43  if (t) {
44  unsigned int v = cmp(key, t->elem);
45  if (v) {
46  if (next) next[v >> 31] = t->elem;
47  return av_tree_find(t->child[(v >> 31) ^ 1], key, cmp, next);
48  } else {
49  if (next) {
50  av_tree_find(t->child[0], key, cmp, next);
51  av_tree_find(t->child[1], key, cmp, next);
52  }
53  return t->elem;
54  }
55  }
56  return NULL;
57 }
58 
59 void *av_tree_insert(AVTreeNode **tp, void *key,
60  int (*cmp)(void *key, const void *b), AVTreeNode **next)
61 {
62  AVTreeNode *t = *tp;
63  if (t) {
64  unsigned int v = cmp(t->elem, key);
65  void *ret;
66  if (!v) {
67  if (*next)
68  return t->elem;
69  else if (t->child[0] || t->child[1]) {
70  int i = !t->child[0];
71  void *next_elem[2];
72  av_tree_find(t->child[i], key, cmp, next_elem);
73  key = t->elem = next_elem[i];
74  v = -i;
75  } else {
76  *next = t;
77  *tp = NULL;
78  return NULL;
79  }
80  }
81  ret = av_tree_insert(&t->child[v >> 31], key, cmp, next);
82  if (!ret) {
83  int i = (v >> 31) ^ !!*next;
84  AVTreeNode **child = &t->child[i];
85  t->state += 2 * i - 1;
86 
87  if (!(t->state & 1)) {
88  if (t->state) {
89  /* The following code is equivalent to
90  if((*child)->state*2 == -t->state)
91  rotate(child, i^1);
92  rotate(tp, i);
93 
94  with rotate():
95  static void rotate(AVTreeNode **tp, int i) {
96  AVTreeNode *t= *tp;
97 
98  *tp= t->child[i];
99  t->child[i]= t->child[i]->child[i^1];
100  (*tp)->child[i^1]= t;
101  i= 4*t->state + 2*(*tp)->state + 12;
102  t ->state= ((0x614586 >> i) & 3)-1;
103  (*tp)->state= ((*tp)->state>>1) + ((0x400EEA >> i) & 3)-1;
104  }
105  but such a rotate function is both bigger and slower
106  */
107  if (( *child )->state * 2 == -t->state) {
108  *tp = (*child)->child[i ^ 1];
109  (*child)->child[i ^ 1] = (*tp)->child[i];
110  (*tp)->child[i] = *child;
111  *child = ( *tp )->child[i ^ 1];
112  (*tp)->child[i ^ 1] = t;
113 
114  (*tp)->child[0]->state = -((*tp)->state > 0);
115  (*tp)->child[1]->state = (*tp)->state < 0;
116  (*tp)->state = 0;
117  } else {
118  *tp = *child;
119  *child = (*child)->child[i ^ 1];
120  (*tp)->child[i ^ 1] = t;
121  if ((*tp)->state) t->state = 0;
122  else t->state >>= 1;
123  (*tp)->state = -t->state;
124  }
125  }
126  }
127  if (!(*tp)->state ^ !!*next)
128  return key;
129  }
130  return ret;
131  } else {
132  *tp = *next;
133  *next = NULL;
134  if (*tp) {
135  (*tp)->elem = key;
136  return NULL;
137  } else
138  return key;
139  }
140 }
141 
143 {
144  if (t) {
145  av_tree_destroy(t->child[0]);
146  av_tree_destroy(t->child[1]);
147  av_free(t);
148  }
149 }
150 
151 void av_tree_enumerate(AVTreeNode *t, void *opaque,
152  int (*cmp)(void *opaque, void *elem),
153  int (*enu)(void *opaque, void *elem))
154 {
155  if (t) {
156  int v = cmp ? cmp(opaque, t->elem) : 0;
157  if (v >= 0)
158  av_tree_enumerate(t->child[0], opaque, cmp, enu);
159  if (v == 0)
160  enu(opaque, t->elem);
161  if (v <= 0)
162  av_tree_enumerate(t->child[1], opaque, cmp, enu);
163  }
164 }
165 
166 #ifdef TEST
167 
168 #include "common.h"
169 #include "lfg.h"
170 
171 static int check(AVTreeNode *t)
172 {
173  if (t) {
174  int left = check(t->child[0]);
175  int right = check(t->child[1]);
176 
177  if (left>999 || right>999)
178  return 1000;
179  if (right - left != t->state)
180  return 1000;
181  if (t->state>1 || t->state<-1)
182  return 1000;
183  return FFMAX(left, right) + 1;
184  }
185  return 0;
186 }
187 
188 static void print(AVTreeNode *t, int depth)
189 {
190  int i;
191  for (i = 0; i < depth * 4; i++) av_log(NULL, AV_LOG_ERROR, " ");
192  if (t) {
193  av_log(NULL, AV_LOG_ERROR, "Node %p %2d %p\n", t, t->state, t->elem);
194  print(t->child[0], depth + 1);
195  print(t->child[1], depth + 1);
196  } else
197  av_log(NULL, AV_LOG_ERROR, "NULL\n");
198 }
199 
200 static int cmp(void *a, const void *b)
201 {
202  return (uint8_t *) a - (const uint8_t *) b;
203 }
204 
205 int main (void)
206 {
207  int i;
208  void *k;
209  AVTreeNode *root = NULL, *node = NULL;
210  AVLFG prng;
211 
212  av_lfg_init(&prng, 1);
213 
214  for (i = 0; i < 10000; i++) {
215  int j = av_lfg_get(&prng) % 86294;
216  if (check(root) > 999) {
217  av_log(NULL, AV_LOG_ERROR, "FATAL error %d\n", i);
218  print(root, 0);
219  return -1;
220  }
221  av_log(NULL, AV_LOG_ERROR, "inserting %4d\n", j);
222  if (!node)
223  node = av_tree_node_alloc();
224  av_tree_insert(&root, (void *) (j + 1), cmp, &node);
225 
226  j = av_lfg_get(&prng) % 86294;
227  {
228  AVTreeNode *node2 = NULL;
229  av_log(NULL, AV_LOG_ERROR, "removing %4d\n", j);
230  av_tree_insert(&root, (void *) (j + 1), cmp, &node2);
231  k = av_tree_find(root, (void *) (j + 1), cmp, NULL);
232  if (k)
233  av_log(NULL, AV_LOG_ERROR, "removal failure %d\n", i);
234  }
235  }
236  return 0;
237 }
238 #endif