[FFmpeg-devel] [RFC] cpu specific implementation of libavutil functions

Michael Niedermayer michaelni
Mon Sep 10 00:27:02 CEST 2007


On Sun, Sep 09, 2007 at 11:23:09PM +0200, Luca Barbato wrote:
> Michael Niedermayer wrote:
> > Hi
> > 
> > On Wed, Sep 05, 2007 at 05:10:50PM +0200, Luca Barbato wrote:
> >> Recently I got an altivec adler32 implementation from Sigbj?rn Skj?ret
> >> and the main issue is how to plant it into libavutils and find a sane
> >> general way.
> > 
> > how much faster is that adler32 code?
> > adler32 really should be limited by memory speed not by cpu
> 4x
> > 2. do we even have a working altivec detection routine? that what we do
> > in dsputil is not what i would call working and i will not accept such
> > hacks in libavutil
> Currently altivec is checked by system dependent reporting or basic
> sigill catching on altivec instruction. I could have an even more crazy
> version like using fork() to execute the altivec code. Still this is to
> my knowledge the only portable way to check.

id say let configure detect it and forget about runtime detection
also solves the problem of how to interface to the code, its just per
#ifdef then

Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

Republics decline into democracies and democracies degenerate into
despotisms. -- Aristotle
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