[Ffmpeg-devel] Fixed vs. Floating Point AAC

[Rich Felker]

On Thu, Mar 09, 2006 at 01:07:41PM -0800, Loren Merritt wrote:
> On Thu, 9 Mar 2006, Michael Niedermayer wrote:
> 
> >so reusing some benchmark proggy here are the results, nicely written and
> >source attached, feel free to design your own cpu which can do
> >integer multiplies faster then floatingpoint ones
> >
> >                       latency throughput
> >P3
> >int     32*32    ->32   4       1
> >int     32*32>>32->32   5.5     1/4.5
> >float   32*32    ->32   5       1/2
> >
> >Duron
> >int     32*32    ->32   4       1/2
> >int     32*32>>32->32   6       1/4.5
> >float   32*32    ->32   3.5     1
> >
> >Athlon
> >int     32*32    ->32   4       1/2
> >int     32*32>>32->32   6.5     1/5
> >float   32*32    ->32   3.5     1
> 
> P4
> int     32*32    ->32   14      1/4.5
> int     32*32>>32->32   19      1/10.5
> float   32*32    ->32    7      1/2

How can 32*32>>32 possibly be slower than 32*32? It's just a matter of
whether you read the result from eax or edx...

Rich