FFmpeg
tree.h
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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 /**
22  * @file
23  * A tree container.
24  * @author Michael Niedermayer <michaelni@gmx.at>
25  */
26 
27 #ifndef AVUTIL_TREE_H
28 #define AVUTIL_TREE_H
29 
30 #include "attributes.h"
31 
32 /**
33  * @addtogroup lavu_tree AVTree
34  * @ingroup lavu_data
35  *
36  * Low-complexity tree container
37  *
38  * Insertion, removal, finding equal, largest which is smaller than and
39  * smallest which is larger than, all have O(log n) worst-case complexity.
40  * @{
41  */
42 
43 
44 struct AVTreeNode;
45 extern const int av_tree_node_size;
46 
47 /**
48  * Allocate an AVTreeNode.
49  */
50 struct AVTreeNode *av_tree_node_alloc(void);
51 
52 /**
53  * Find an element.
54  * @param root a pointer to the root node of the tree
55  * @param next If next is not NULL, then next[0] will contain the previous
56  * element and next[1] the next element. If either does not exist,
57  * then the corresponding entry in next is unchanged.
58  * @param cmp compare function used to compare elements in the tree,
59  * API identical to that of Standard C's qsort
60  * It is guaranteed that the first and only the first argument to cmp()
61  * will be the key parameter to av_tree_find(), thus it could if the
62  * user wants, be a different type (like an opaque context).
63  * @return An element with cmp(key, elem) == 0 or NULL if no such element
64  * exists in the tree.
65  */
66 void *av_tree_find(const struct AVTreeNode *root, void *key,
67  int (*cmp)(const void *key, const void *b), void *next[2]);
68 
69 /**
70  * Insert or remove an element.
71  *
72  * If *next is NULL, then the supplied element will be removed if it exists.
73  * If *next is non-NULL, then the supplied element will be inserted, unless
74  * it already exists in the tree.
75  *
76  * @param rootp A pointer to a pointer to the root node of the tree; note that
77  * the root node can change during insertions, this is required
78  * to keep the tree balanced.
79  * @param key pointer to the element key to insert in the tree
80  * @param next Used to allocate and free AVTreeNodes. For insertion the user
81  * must set it to an allocated and zeroed object of at least
82  * av_tree_node_size bytes size. av_tree_insert() will set it to
83  * NULL if it has been consumed.
84  * For deleting elements *next is set to NULL by the user and
85  * av_tree_insert() will set it to the AVTreeNode which was
86  * used for the removed element.
87  * This allows the use of flat arrays, which have
88  * lower overhead compared to many malloced elements.
89  * You might want to define a function like:
90  * @code
91  * void *tree_insert(struct AVTreeNode **rootp, void *key,
92  * int (*cmp)(void *key, const void *b),
93  * AVTreeNode **next)
94  * {
95  * if (!*next)
96  * *next = av_mallocz(av_tree_node_size);
97  * return av_tree_insert(rootp, key, cmp, next);
98  * }
99  * void *tree_remove(struct AVTreeNode **rootp, void *key,
100  * int (*cmp)(void *key, const void *b, AVTreeNode **next))
101  * {
102  * av_freep(next);
103  * return av_tree_insert(rootp, key, cmp, next);
104  * }
105  * @endcode
106  * @param cmp compare function used to compare elements in the tree, API identical
107  * to that of Standard C's qsort
108  * @return If no insertion happened, the found element; if an insertion or
109  * removal happened, then either key or NULL will be returned.
110  * Which one it is depends on the tree state and the implementation. You
111  * should make no assumptions that it's one or the other in the code.
112  */
113 void *av_tree_insert(struct AVTreeNode **rootp, void *key,
114  int (*cmp)(const void *key, const void *b),
115  struct AVTreeNode **next);
116 
117 void av_tree_destroy(struct AVTreeNode *t);
118 
119 /**
120  * Apply enu(opaque, &elem) to all the elements in the tree in a given range.
121  *
122  * @param cmp a comparison function that returns < 0 for an element below the
123  * range, > 0 for an element above the range and == 0 for an
124  * element inside the range
125  *
126  * @note The cmp function should use the same ordering used to construct the
127  * tree.
128  */
129 void av_tree_enumerate(struct AVTreeNode *t, void *opaque,
130  int (*cmp)(void *opaque, void *elem),
131  int (*enu)(void *opaque, void *elem));
132 
133 /**
134  * @}
135  */
136 
137 #endif /* AVUTIL_TREE_H */
av_tree_insert
void * av_tree_insert(struct AVTreeNode **rootp, void *key, int(*cmp)(const void *key, const void *b), struct AVTreeNode **next)
Insert or remove an element.
Definition: tree.c:59
AVTreeNode::elem
void * elem
Definition: tree.c:28
b
#define b
Definition: input.c:41
av_tree_node_alloc
struct AVTreeNode * av_tree_node_alloc(void)
Allocate an AVTreeNode.
Definition: tree.c:34
av_tree_enumerate
void av_tree_enumerate(struct AVTreeNode *t, void *opaque, int(*cmp)(void *opaque, void *elem), int(*enu)(void *opaque, void *elem))
Apply enu(opaque, &elem) to all the elements in the tree in a given range.
Definition: tree.c:155
av_tree_node_size
const int av_tree_node_size
Definition: tree.c:32
key
const char * key
Definition: hwcontext_opencl.c:179
cmp
static av_always_inline int cmp(MpegEncContext *s, const int x, const int y, const int subx, const int suby, const int size, const int h, int ref_index, int src_index, me_cmp_func cmp_func, me_cmp_func chroma_cmp_func, const int flags)
compares a block (either a full macroblock or a partition thereof) against a proposed motion-compensa...
Definition: motion_est.c:262
AVTreeNode
Definition: tree.c:26
av_tree_destroy
void av_tree_destroy(struct AVTreeNode *t)
Definition: tree.c:146
attributes.h
av_tree_find
void * av_tree_find(const struct AVTreeNode *root, void *key, int(*cmp)(const void *key, const void *b), void *next[2])
Find an element.