[FFmpeg-devel] [PATCH 2/3] avfilter/avfilter: avfilter_register() that works in O(1) time

[Michael Niedermayer]

This also flips the order of the list
avfilters should be unique and thus the order should not matter

Signed-off-by: Michael Niedermayer <michaelni at gmx.at>
---
 libavfilter/avfilter.c |    8 +++-----
 1 file changed, 3 insertions(+), 5 deletions(-)

diff --git a/libavfilter/avfilter.c b/libavfilter/avfilter.c
index 2567ce9..c564b45 100644
--- a/libavfilter/avfilter.c
+++ b/libavfilter/avfilter.c
@@ -476,7 +476,6 @@ AVFilter *avfilter_get_by_name(const char *name)
 
 int avfilter_register(AVFilter *filter)
 {
-    AVFilter **f = &first_filter;
     int i;
 
     /* the filter must select generic or internal exclusively */
@@ -488,10 +487,9 @@ int avfilter_register(AVFilter *filter)
                     || (!input->start_frame && !input->end_frame));
     }
 
-    filter->next = NULL;
-
-    while(*f || avpriv_atomic_ptr_cas((void * volatile *)f, NULL, filter))
-        f = &(*f)->next;
+    do {
+        filter->next = first_filter;
+    } while (filter->next != avpriv_atomic_ptr_cas((void * volatile *)&first_filter, filter->next, filter));
 
     return 0;
 }
-- 
1.7.9.5