[linux-audio-dev] interesting post from vst-plugins on float/int

Steve Harris S.W.Harris at ecs.soton.ac.uk
Tue Sep 17 14:56:58 UTC 2002

On Tue, Sep 17, 2002 at 04:07:58 +0200, Tim Goetze wrote:
> unfortunately there's nothing in
> http://gcc.gnu.org/gcc-3.0/features.html that would suggest this.

http://gcc.gnu.org/gcc-3.1/changes.html -mmmx -m3dnow etc. It can;t
vectgorise (by the sound of it) but it can do substituion and presumably
handle the register shifts?
> applying static gain seems to be a good candidate for SIMD even if
> there's only one channel. needs some additional logic if buffers

Yes, also the normalised float -> integer conversion that is done in eg.
jacks output loop. It could be made branchless (and vectorised, unless you
are dithering).

> with the need for [f]emms and gcc's crude inline assembly syntax, it
> seems very desirable to isolate vectorized routines into .s sources
> to me.

Maybe, I've not done any serious inline assembler code in gcc. I'd be
interested in mucking in on a library of accelerated functions though,
it's an area I want to know more about.

- Steve

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