mirror of
https://git.ffmpeg.org/ffmpeg.git
synced 2024-12-21 06:50:44 +00:00
82 lines
3.7 KiB
C
82 lines
3.7 KiB
C
/*
|
|
* 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
|
|
*/
|
|
|
|
/**
|
|
* @file tree.h
|
|
* A tree container.
|
|
* Insertion, Removial, Finding equal, largest which is smaller than and
|
|
* smallest which is larger than all have O(log n) worst case time.
|
|
* @author Michael Niedermayer <michaelni@gmx.at>
|
|
*/
|
|
|
|
#ifndef AVUTIL_TREE_H
|
|
#define AVUTIL_TREE_H
|
|
|
|
struct AVTreeNode;
|
|
extern const int av_tree_node_size;
|
|
|
|
/**
|
|
* Finds an element.
|
|
* @param root a pointer to the root node of the tree
|
|
* @param next If next is not NULL then next[0] will contain the previous
|
|
* element and next[1] the next element if either does not exist
|
|
* then the corresponding entry in next is unchanged.
|
|
* @return An element with cmp(key, elem)==0 or NULL if no such element exists in
|
|
* the tree.
|
|
*/
|
|
void *av_tree_find(const struct AVTreeNode *root, void *key, int (*cmp)(void *key, const void *b), void *next[2]);
|
|
|
|
/**
|
|
* Inserts or removes an element.
|
|
* If *next is NULL then the element supplied will be removed if it exists.
|
|
* If *next is not NULL then the element supplied will be inserted, unless
|
|
* it already exists in the tree.
|
|
* @param rootp A pointer to a pointer to the root node of the tree. Note that
|
|
* the root node can change during insertions, this is required
|
|
* to keep the tree balanced.
|
|
* @param next Used to allocate and free AVTreeNodes. For insertion the user
|
|
* must set it to an allocated and zeroed object of at least
|
|
* av_tree_node_size bytes size. av_tree_insert() will set it to
|
|
* NULL if it has been consumed.
|
|
* For deleting elements *next is set to NULL by the user and
|
|
* av_tree_node_size() will set it to the AVTreeNode which was
|
|
* used for the removed element.
|
|
* This allows the use of flat arrays, which have
|
|
* lower overhead compared to many malloced elements.
|
|
* You might want to define a function like:
|
|
* void *tree_insert(struct AVTreeNode **rootp, void *key, int (*cmp)(void *key, const void *b), AVTreeNode **next){
|
|
* if(!*next) *next= av_mallocz(av_tree_node_size);
|
|
* return av_tree_insert(rootp, key, cmp, next);
|
|
* }
|
|
* void *tree_remove(struct AVTreeNode **rootp, void *key, int (*cmp)(void *key, const void *b, AVTreeNode **next)){
|
|
* if(*next) av_freep(next);
|
|
* return av_tree_insert(rootp, key, cmp, next);
|
|
* }
|
|
*
|
|
* @return If no insertion happened, the found element.
|
|
* If an insertion or removial happened, then either key or NULL will be returned.
|
|
* Which one it is depends on the tree state and the implementation. You
|
|
* should make no assumptions that it's one or the other in the code.
|
|
*/
|
|
void *av_tree_insert(struct AVTreeNode **rootp, void *key, int (*cmp)(void *key, const void *b), struct AVTreeNode **next);
|
|
void av_tree_destroy(struct AVTreeNode *t);
|
|
|
|
#endif /* AVUTIL_TREE_H */
|