[Ffmpeg-devel] clever 8-bit MMX loop filter ABS test

[Michael Niedermayer]

Hi

On Tuesday 03 May 2005 11:03, Skal wrote:
[...]
> %macro ABS_LESS_SSE 2     ;   %1:out reg  %2: alpha-1/beta-1  mm0:Px mm1:Qx
>  Trashes mm0,mm1,mm2 
>   movq    mm2, mm0  ; Save Po 
>   psubusb mm0, mm1  ; Po-Qo
>   psubusb mm1, mm2  ; Qo-Po
>   psubusb mm0,  %2
>   psubusb mm1,  %2
>   por     mm1, mm0
>   pxor     %1,  %1
>   pcmpeqb  %1, mm1

   movq    mm2, mm0  ; Save Po 
   psubusb mm0, %1   ; Po-Qo
   psubusb %1, mm2   ; Qo-Po
   por     %1, mm0
   psubusb %1,  %2
   pcmpeqb  %1, mm7
is 2 instructions less and should be faster

[...]
-- 
Michael

"nothing is evil in the beginning. Even Sauron was not so." -- Elrond