Subject: Re: [linux-audio-dev] Fixed vs Floating point comparison.
From: Paul Davis (paul_AT_linuxaudiosystems.com)
Date: Fri Oct 17 2003 - 18:20:10 EEST
>This was indeed interesting, I set out to prove that floating point would be
>the better choice from a performance perspective, but I can't do that,
>atleast not judging from the data from my systems!
in most typical systems, the conversion between integer and FP formats
happens once per interrupt. this cost, whatever it is, is *dwarfed* by
the cycles used between interrupts for actual processing of that
data. this is one of the motivations behind JACK's architecture, where
the conversion is guaranteed to happen only once, and you, the
programmer of a JACK client, doesn't bother with int<->float
conversion anywhere.
if you're writing software where you do this conversion more than once
per interrupt, i think it probably needs a redesign. if the cost of
the conversion is an appreciable fraction of the over
cycles/interrupt, then and only then does it seem to make sense to me
to consider *not* using float.
--p
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