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avformat/format: av_register_output_format() and av_register_intput_format() that work in O(1) time

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Reviewed-by: Stefano Sabatini
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
This commit is contained in:
Michael Niedermayer
2013-12-08 02:29:28 +01:00
parent ec464c9683
commit 49f10c9cb1
1 changed files with 7 additions and 2 deletions
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9
libavformat/format.c
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@@ -33,6 +33,9 @@ static AVInputFormat *first_iformat = NULL;
/** head of registered output format linked list */ /** head of registered output format linked list */
static AVOutputFormat *first_oformat = NULL; static AVOutputFormat *first_oformat = NULL;
static AVInputFormat **last_iformat = &first_iformat;
static AVOutputFormat **last_oformat = &first_oformat;
AVInputFormat *av_iformat_next(AVInputFormat *f) AVInputFormat *av_iformat_next(AVInputFormat *f)
{ {
if (f) if (f)
@@ -51,20 +54,22 @@ AVOutputFormat *av_oformat_next(AVOutputFormat *f)
void av_register_input_format(AVInputFormat *format) void av_register_input_format(AVInputFormat *format)
{ {
AVInputFormat **p = &first_iformat; AVInputFormat **p = last_iformat;
format->next = NULL; format->next = NULL;
while(*p || avpriv_atomic_ptr_cas((void * volatile *)p, NULL, format)) while(*p || avpriv_atomic_ptr_cas((void * volatile *)p, NULL, format))
p = &(*p)->next; p = &(*p)->next;
last_iformat = &format->next;
} }
void av_register_output_format(AVOutputFormat *format) void av_register_output_format(AVOutputFormat *format)
{ {
AVOutputFormat **p = &first_oformat; AVOutputFormat **p = last_oformat;
format->next = NULL; format->next = NULL;
while(*p || avpriv_atomic_ptr_cas((void * volatile *)p, NULL, format)) while(*p || avpriv_atomic_ptr_cas((void * volatile *)p, NULL, format))
p = &(*p)->next; p = &(*p)->next;
last_oformat = &format->next;
} }
int av_match_ext(const char *filename, const char *extensions) int av_match_ext(const char *filename, const char *extensions)