[FFmpeg-cvslog] r18599 - trunk/libavcodec/xan.c

[Reimar Döffinger]

On Fri, Apr 17, 2009 at 10:05:27PM +0200, reimar wrote:
> Author: reimar
> Date: Fri Apr 17 22:05:27 2009
> New Revision: 18599
> 
> Log:
> Use sign_extend function instead of reimplementing it.
> 
> Modified:
>    trunk/libavcodec/xan.c
> 
> Modified: trunk/libavcodec/xan.c
> ==============================================================================
> --- trunk/libavcodec/xan.c	Fri Apr 17 22:01:45 2009	(r18598)
> +++ trunk/libavcodec/xan.c	Fri Apr 17 22:05:27 2009	(r18599)
> @@ -333,16 +333,10 @@ static void xan_wc3_decode_frame(XanCont
>              }
>          } else {
>              /* run-based motion compensation from last frame */
> -            motion_x = *vector_segment >> 4;
> -            motion_y = *vector_segment & 0xF;
> +            motion_x = sign_extend(*vector_segment >> 4,  4);
> +            motion_y = sign_extend(*vector_segment & 0xF, 4);

Someone forgot to document sign_extend, should I be doing the "& 0xF"
or can I assume that any future optimized implementation will flush
the upper bits, too?