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 (*f)(void *opaque, void *elem)){
 140     int v= f(opaque, t->elem);
 141     if(v>=0) av_tree_enumerate(t->child[0], opaque, f);
 142     if(v<=0) av_tree_enumerate(t->child[1], opaque, f);
 143 }
 144 #endif
 145
 146 #ifdef TEST
 147 #undef random
 148 static int check(AVTreeNode *t){
 149     if(t){
 150         int left= check(t->child[0]);
 151         int right= check(t->child[1]);
 152
 153         if(left>999 || right>999)
 154             return 1000;
 155         if(right - left != t->state)
 156             return 1000;
 157         if(t->state>1 || t->state<-1)
 158             return 1000;
 159         return FFMAX(left, right)+1;
 160     }
 161     return 0;
 162 }
 163
 164 static void print(AVTreeNode *t, int depth){
 165     int i;
 166     for(i=0; i<depth*4; i++) av_log(NULL, AV_LOG_ERROR, " ");
 167     if(t){
 168         av_log(NULL, AV_LOG_ERROR, "Node %p %2d %4d\n", t, t->state, t->elem);
 169         print(t->child[0], depth+1);
 170         print(t->child[1], depth+1);
 171     }else
 172         av_log(NULL, AV_LOG_ERROR, "NULL\n");
 173 }
 174
 175 int cmp(const void *a, const void *b){
 176     return a-b;
 177 }
 178
 179 int main(void){
 180     int i,k;
 181     AVTreeNode *root= NULL, *node=NULL;
 182
 183     for(i=0; i<10000; i++){
 184         int j= (random()%86294);
 185         if(check(root) > 999){
 186             av_log(NULL, AV_LOG_ERROR, "FATAL error %d\n", i);
 187         print(root, 0);
 188             return -1;
 189         }
 190         av_log(NULL, AV_LOG_ERROR, "inserting %4d\n", j);
 191         if(!node)
 192             node= av_mallocz(av_tree_node_size);
 193         av_tree_insert(&root, (void*)(j+1), cmp, &node);
 194
 195         j= (random()%86294);
 196         {
 197             AVTreeNode *node2=NULL;
 198             av_log(NULL, AV_LOG_ERROR, "removing %4d\n", j);
 199             av_tree_insert(&root, (void*)(j+1), cmp, &node2);
 200             k= av_tree_find(root, (void*)(j+1), cmp, NULL);
 201             if(k)
 202                 av_log(NULL, AV_LOG_ERROR, "removial failure %d\n", i);
 203         }
 204     }
 205     return 0;
 206 }
 207 #endif