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    /*
     * copyright (c) 2006 Michael Niedermayer <michaelni@gmx.at>
     *
     * This file is part of FFmpeg.
     *
     * FFmpeg is free software; you can redistribute it and/or
     * modify it under the terms of the GNU Lesser General Public
     * License as published by the Free Software Foundation; either
     * version 2.1 of the License, or (at your option) any later version.
     *
     * FFmpeg is distributed in the hope that it will be useful,
     * but WITHOUT ANY WARRANTY; without even the implied warranty of
     * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
     * Lesser General Public License for more details.
     *
     * You should have received a copy of the GNU Lesser General Public
     * License along with FFmpeg; if not, write to the Free Software
     * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
     */
    
    #include "common.h"
    #include "log.h"
    #include "tree.h"
    
    typedef struct AVTreeNode{
        struct AVTreeNode *child[2];
        void *elem;
        int state;
    }AVTreeNode;
    
    void *av_tree_find(const AVTreeNode *t, void *key, int (*cmp)(void *key, const void *b), void *next[2]){
        if(t){
            unsigned int v= cmp(t->elem, key);
            if(v){
                if(next) next[(v>>31)^1]= t->elem;
                return av_tree_find(t->child[v>>31], key, cmp, next);
            }else{
                return t->elem;
            }
        }
        return NULL;
    }
    
    void *av_tree_insert(AVTreeNode **tp, void *key, int (*cmp)(void *key, const void *b)){
        AVTreeNode *t= *tp;
        if(t){
            unsigned int v= cmp(t->elem, key);
            if(v){
                int i= v>>31;
                AVTreeNode **child= &t->child[i];
                void *ret= av_tree_insert(child, key, cmp);
                if(!ret){
                    t->state -= ((int)v>>31)|1;
                    if(!(t->state&1)){
                        if(t->state){
                            if((*child)->state*2 == t->state){
                                *tp= *child;
                                *child= (*child)->child[i^1];
                                (*tp)->child[i^1]= t;
                                t->state= 0;
                            }else{
                                *tp= (*child)->child[i^1];
                                (*child)->child[i^1]= (*tp)->child[i];
                                (*tp)->child[i]= *child;
                                *child= (*tp)->child[i^1];
                                (*tp)->child[i^1]= t;
    
                                i= (*tp)->state > 0;
                                (*tp)->child[i  ]->state= 0;
                                (*tp)->child[i^1]->state= -(*tp)->state;
                            }
                            (*tp)->state=0;
                        }
                        return key;
                    }
                }
                return ret;
            }else{
                return t->elem;
            }
        }else{
            *tp= av_mallocz(sizeof(AVTreeNode));
            (*tp)->elem= key;
            return NULL;
        }
    }
    
    void av_tree_destroy(AVTreeNode *t){
        av_tree_destroy(t->child[0]);
        av_tree_destroy(t->child[1]);
        av_free(t);
    }
    
    #if 0
    void av_tree_enumerate(AVTreeNode *t, void *opaque, int (*f)(void *opaque, void *elem)){
        f(opaque, t->elem);
        av_tree_enumerate(t->child[0], opaque, f);
        av_tree_enumerate(t->child[1], opaque, f);
    }
    #endif
    
    #ifdef TEST
    
    static int check(AVTreeNode *t){
        if(t){
            int left= check(t->child[0]);
            int right= check(t->child[1]);
    
            if(left>999 || right>999)
                return 1000;
            if(right - left != t->state)
                return 1000;
            if(t->state>1 || t->state<-1)
                return 1000;
            return FFMAX(left, right)+1;
        }
        return 0;
    }
    
    static void print(AVTreeNode *t, int depth){
        int i;
        for(i=0; i<depth*4; i++) av_log(NULL, AV_LOG_ERROR, " ");
        if(t){
            av_log(NULL, AV_LOG_ERROR, "Node %p %2d %4d\n", t, t->state, t->elem);
            print(t->child[0], depth+1);
            print(t->child[1], depth+1);
        }else
            av_log(NULL, AV_LOG_ERROR, "NULL\n");
    }
    
    int cmp(const void *a, const void *b){
        return a-b;
    }
    
    int main(){
        int i,j,k;
        AVTreeNode *root= av_mallocz(sizeof(AVTreeNode));
    
        for(i=0; i<10000; i++){
            int j= (random()%863294);
            if(check(root) > 999){
                av_log(NULL, AV_LOG_ERROR, "FATAL error %d\n", i);
            print(root, 0);
                return -1;
            }
            av_log(NULL, AV_LOG_ERROR, "inserting %4d\n", j);
            av_tree_insert(&root, (void*)(j+1), cmp);
        }
        return 0;
    }
    #endif