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ffmpeg / libavutil / tree.c @ fee6faa2

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/*
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 * copyright (c) 2006 Michael Niedermayer <michaelni@gmx.at>
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 *
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 * This file is part of FFmpeg.
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 *
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 * FFmpeg is free software; you can redistribute it and/or
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 * modify it under the terms of the GNU Lesser General Public
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 * License as published by the Free Software Foundation; either
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 * version 2.1 of the License, or (at your option) any later version.
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 *
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 * FFmpeg is distributed in the hope that it will be useful,
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 * but WITHOUT ANY WARRANTY; without even the implied warranty of
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 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
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 * Lesser General Public License for more details.
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 *
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 * You should have received a copy of the GNU Lesser General Public
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 * License along with FFmpeg; if not, write to the Free Software
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 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
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 */
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#include "common.h"
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#include "log.h"
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#include "tree.h"
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typedef struct AVTreeNode{
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    struct AVTreeNode *child[2];
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    void *elem;
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    int state;
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}AVTreeNode;
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const int av_tree_node_size = sizeof(AVTreeNode);
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void *av_tree_find(const AVTreeNode *t, void *key, int (*cmp)(void *key, const void *b), void *next[2]){
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    if(t){
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        unsigned int v= cmp(key, t->elem);
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        if(v){
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            if(next) next[v>>31]= t->elem;
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            return av_tree_find(t->child[(v>>31)^1], key, cmp, next);
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        }else{
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            if(next){
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                av_tree_find(t->child[0], key, cmp, next);
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                av_tree_find(t->child[1], key, cmp, next);
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            }
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            return t->elem;
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        }
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    }
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    return NULL;
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}
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void *av_tree_insert(AVTreeNode **tp, void *key, int (*cmp)(void *key, const void *b), AVTreeNode **next){
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    AVTreeNode *t= *tp;
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    if(t){
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        unsigned int v= cmp(t->elem, key);
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        void *ret;
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        if(!v){
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            if(*next)
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                return t->elem;
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            else if(t->child[0]||t->child[1]){
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                int i= !t->child[0];
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                void *next_elem[2];
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                av_tree_find(t->child[i], key, cmp, next_elem);
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                key= t->elem= next_elem[i];
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                v= -i;
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            }else{
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                *next= t;
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                *tp=NULL;
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                return NULL;
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            }
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        }
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        ret= av_tree_insert(&t->child[v>>31], key, cmp, next);
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        if(!ret){
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            int i= (v>>31) ^ !!*next;
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            AVTreeNode **child= &t->child[i];
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            t->state += 2*i - 1;
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            if(!(t->state&1)){
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                if(t->state){
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                    /* The following code is equivalent to
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                    if((*child)->state*2 == -t->state)
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                        rotate(child, i^1);
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                    rotate(tp, i);
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                    with rotate():
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                    static void rotate(AVTreeNode **tp, int i){
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                        AVTreeNode *t= *tp;
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                        *tp= t->child[i];
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                        t->child[i]= t->child[i]->child[i^1];
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                        (*tp)->child[i^1]= t;
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                        i= 4*t->state + 2*(*tp)->state + 12;
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                          t  ->state=                     ((0x614586 >> i) & 3)-1;
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                        (*tp)->state= ((*tp)->state>>1) + ((0x400EEA >> i) & 3)-1;
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                    }
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                    but such a rotate function is both bigger and slower
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                    */
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                    if((*child)->state*2 == -t->state){
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                        *tp= (*child)->child[i^1];
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                        (*child)->child[i^1]= (*tp)->child[i];
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                        (*tp)->child[i]= *child;
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                        *child= (*tp)->child[i^1];
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                        (*tp)->child[i^1]= t;
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                        (*tp)->child[0]->state= -((*tp)->state>0);
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                        (*tp)->child[1]->state=   (*tp)->state<0 ;
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                        (*tp)->state=0;
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                    }else{
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                        *tp= *child;
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                        *child= (*child)->child[i^1];
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                        (*tp)->child[i^1]= t;
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                        if((*tp)->state) t->state  = 0;
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                        else             t->state>>= 1;
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                        (*tp)->state= -t->state;
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                    }
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                }
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            }
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            if(!(*tp)->state ^ !!*next)
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                return key;
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        }
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        return ret;
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    }else{
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        *tp= *next; *next= NULL;
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        if(*tp){
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            (*tp)->elem= key;
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            return NULL;
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        }else
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            return key;
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    }
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}
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void av_tree_destroy(AVTreeNode *t){
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    if(t){
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        av_tree_destroy(t->child[0]);
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        av_tree_destroy(t->child[1]);
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        av_free(t);
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    }
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}
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void av_tree_destroy_free_elem(AVTreeNode *t){
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    if(t){
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        av_tree_destroy_free_elem(t->child[0]);
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        av_tree_destroy_free_elem(t->child[1]);
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        av_free(t->elem);
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        av_free(t);
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    }
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}
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#if 0
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void av_tree_enumerate(AVTreeNode *t, void *opaque, int (*cmp)(void *opaque, void *elem), int (*enu)(void *opaque, void *elem)){
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    if(t){
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        int v= cmp ? cmp(opaque, t->elem) : 0;
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        if(v>=0) av_tree_enumerate(t->child[0], opaque, cmp, enu);
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        if(v==0) enu(opaque, t->elem);
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        if(v<=0) av_tree_enumerate(t->child[1], opaque, cmp, enu);
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    }
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}
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#endif
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#ifdef TEST
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#include "lfg.h"
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static int check(AVTreeNode *t){
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    if(t){
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        int left= check(t->child[0]);
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        int right= check(t->child[1]);
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        if(left>999 || right>999)
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            return 1000;
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        if(right - left != t->state)
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            return 1000;
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        if(t->state>1 || t->state<-1)
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            return 1000;
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        return FFMAX(left, right)+1;
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    }
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    return 0;
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}
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static void print(AVTreeNode *t, int depth){
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    int i;
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    for(i=0; i<depth*4; i++) av_log(NULL, AV_LOG_ERROR, " ");
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    if(t){
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        av_log(NULL, AV_LOG_ERROR, "Node %p %2d %p\n", t, t->state, t->elem);
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        print(t->child[0], depth+1);
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        print(t->child[1], depth+1);
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    }else
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        av_log(NULL, AV_LOG_ERROR, "NULL\n");
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}
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static int cmp(void *a, const void *b){
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    return (uint8_t*)a-(const uint8_t*)b;
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}
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int main(void){
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    int i;
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    void *k;
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    AVTreeNode *root= NULL, *node=NULL;
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    AVLFG prng;
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    av_lfg_init(&prng, 1);
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    for(i=0; i<10000; i++){
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        int j = av_lfg_get(&prng) % 86294;
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        if(check(root) > 999){
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            av_log(NULL, AV_LOG_ERROR, "FATAL error %d\n", i);
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        print(root, 0);
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            return -1;
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        }
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        av_log(NULL, AV_LOG_ERROR, "inserting %4d\n", j);
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        if(!node)
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            node= av_mallocz(av_tree_node_size);
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        av_tree_insert(&root, (void*)(j+1), cmp, &node);
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        j = av_lfg_get(&prng) % 86294;
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        {
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            AVTreeNode *node2=NULL;
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            av_log(NULL, AV_LOG_ERROR, "removing %4d\n", j);
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            av_tree_insert(&root, (void*)(j+1), cmp, &node2);
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            k= av_tree_find(root, (void*)(j+1), cmp, NULL);
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            if(k)
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                av_log(NULL, AV_LOG_ERROR, "removal failure %d\n", i);
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        }
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    }
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    return 0;
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}
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#endif