[FFmpeg-devel] [PATCH] Fix unaligned access in lcl decoder

[Jeff Downs]

On Wed, 27 May 2009, Michael Niedermayer wrote:

> On Wed, May 27, 2009 at 12:22:19PM -0400, Jeff Downs wrote:
> > Attached fixes by using memcpy instead of integer copies on platforms 
> > without fast unaligned access.
> 
> AV_R/WN32() might be more appropriate than the ifdeffery
> 

Much cleaner looking, yes. Attached.

Probably a slight speed hit on platforms where AV_R/WN32 are non-optimized 
though due to all the shifts. I don't have a platform where that is 
realistically the case to test it on, but if I force that implementation 
it is slower than memcpy (2% with the test sample on sparc).

	-Jeff
-------------- next part --------------
Index: libavcodec/lcldec.c
===================================================================
--- libavcodec/lcldec.c	(revision 18893)
+++ libavcodec/lcldec.c	(working copy)
@@ -129,7 +129,7 @@
         if ((mask & (1 << (--maskbit))) == 0) {
             if (destptr + 4 > destptr_end)
                 break;
-            *(int*)destptr = *(int*)srcptr;
+            AV_WN32(destptr, AV_RN32(srcptr));
             srclen -= 4;
             destptr += 4;
             srcptr += 4;