libavutil/tree.c

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