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
25typedef struct AVTreeNode{
26    struct AVTreeNode *child[2];
27    void *elem;
28    int state;
29}AVTreeNode;
30
31const int av_tree_node_size = sizeof(AVTreeNode);
32
33void *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
50void *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
130void 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
139void 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
148static 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
164static 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
175int cmp(const void *a, const void *b){
176    return a-b;
177}
178
179int 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, "removal failure %d\n", i);
203        }
204    }
205    return 0;
206}
207#endif
208