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