pixdesc: Reindent after previous commit
[ffmpeg.git] / 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 "error.h"
22 #include "log.h"
23 #include "mem.h"
24 #include "tree.h"
25
26 typedef struct AVTreeNode {
27     struct AVTreeNode *child[2];
28     void *elem;
29     int state;
30 } AVTreeNode;
31
32 const int av_tree_node_size = sizeof(AVTreeNode);
33
34 struct AVTreeNode *av_tree_node_alloc(void)
35 {
36     return av_mallocz(sizeof(struct AVTreeNode));
37 }
38
39 void *av_tree_find(const AVTreeNode *t, void *key,
40                    int (*cmp)(const void *key, const void *b), void *next[2])
41 {
42     if (t) {
43         unsigned int v = cmp(key, t->elem);
44         if (v) {
45             if (next)
46                 next[v >> 31] = t->elem;
47             return av_tree_find(t->child[(v >> 31) ^ 1], key, cmp, next);
48         } else {
49             if (next) {
50                 av_tree_find(t->child[0], key, cmp, next);
51                 av_tree_find(t->child[1], key, cmp, next);
52             }
53             return t->elem;
54         }
55     }
56     return NULL;
57 }
58
59 void *av_tree_insert(AVTreeNode **tp, void *key,
60                      int (*cmp)(const void *key, const void *b), AVTreeNode **next)
61 {
62     AVTreeNode *t = *tp;
63     if (t) {
64         unsigned int v = cmp(t->elem, key);
65         void *ret;
66         if (!v) {
67             if (*next)
68                 return t->elem;
69             else if (t->child[0] || t->child[1]) {
70                 int i = !t->child[0];
71                 void *next_elem[2];
72                 av_tree_find(t->child[i], key, cmp, next_elem);
73                 key = t->elem = next_elem[i];
74                 v   = -i;
75             } else {
76                 *next = t;
77                 *tp   = NULL;
78                 return NULL;
79             }
80         }
81         ret = av_tree_insert(&t->child[v >> 31], key, cmp, next);
82         if (!ret) {
83             int i              = (v >> 31) ^ !!*next;
84             AVTreeNode **child = &t->child[i];
85             t->state += 2 * i - 1;
86
87             if (!(t->state & 1)) {
88                 if (t->state) {
89                     /* The following code is equivalent to
90                      * if ((*child)->state * 2 == -t->state)
91                      *     rotate(child, i ^ 1);
92                      * rotate(tp, i);
93                      *
94                      * with rotate():
95                      * static void rotate(AVTreeNode **tp, int i)
96                      * {
97                      *     AVTreeNode *t= *tp;
98                      *
99                      *     *tp = t->child[i];
100                      *     t->child[i] = t->child[i]->child[i ^ 1];
101                      *     (*tp)->child[i ^ 1] = t;
102                      *     i = 4 * t->state + 2 * (*tp)->state + 12;
103                      *     t->state     = ((0x614586 >> i) & 3) - 1;
104                      *     (*tp)->state = ((0x400EEA >> i) & 3) - 1 +
105                      *                    ((*tp)->state >> 1);
106                      * }
107                      * but such a rotate function is both bigger and slower
108                      */
109                     if ((*child)->state * 2 == -t->state) {
110                         *tp                    = (*child)->child[i ^ 1];
111                         (*child)->child[i ^ 1] = (*tp)->child[i];
112                         (*tp)->child[i]        = *child;
113                         *child                 = (*tp)->child[i ^ 1];
114                         (*tp)->child[i ^ 1]    = t;
115
116                         (*tp)->child[0]->state = -((*tp)->state > 0);
117                         (*tp)->child[1]->state = (*tp)->state < 0;
118                         (*tp)->state           = 0;
119                     } else {
120                         *tp                 = *child;
121                         *child              = (*child)->child[i ^ 1];
122                         (*tp)->child[i ^ 1] = t;
123                         if ((*tp)->state)
124                             t->state = 0;
125                         else
126                             t->state >>= 1;
127                         (*tp)->state = -t->state;
128                     }
129                 }
130             }
131             if (!(*tp)->state ^ !!*next)
132                 return key;
133         }
134         return ret;
135     } else {
136         *tp   = *next;
137         *next = NULL;
138         if (*tp) {
139             (*tp)->elem = key;
140             return NULL;
141         } else
142             return key;
143     }
144 }
145
146 void av_tree_destroy(AVTreeNode *t)
147 {
148     if (t) {
149         av_tree_destroy(t->child[0]);
150         av_tree_destroy(t->child[1]);
151         av_free(t);
152     }
153 }
154
155 void av_tree_enumerate(AVTreeNode *t, void *opaque,
156                        int (*cmp)(void *opaque, void *elem),
157                        int (*enu)(void *opaque, void *elem))
158 {
159     if (t) {
160         int v = cmp ? cmp(opaque, t->elem) : 0;
161         if (v >= 0)
162             av_tree_enumerate(t->child[0], opaque, cmp, enu);
163         if (v == 0)
164             enu(opaque, t->elem);
165         if (v <= 0)
166             av_tree_enumerate(t->child[1], opaque, cmp, enu);
167     }
168 }