Subject: Re: [linux-audio-dev] EVO 0.0.5 released , resampling (interpolation) support added
From: Paul Barton-Davis (pbd_AT_Op.Net)
Date: Tue Sep 19 2000 - 16:55:46 EEST
Benno writes:
>PS: thank's to Intels DISASTROUS floatint point to int conversion
>(read the music-dsp archives for the reason of this),
>EVO uses an indecent amount of CPU because
>a simple pos_int=(int)pos; (pos is a double).
>I did not believe it when I saw it:
>36 voices without the (int) statement: about 22% CPU usage, which
>is quite good.
>
>with the (int) statement (which is needed to calculate the
>int and fract part of the pos in the case of interpolation),
>a CPU usage of 50% was measured !!
>The solution lies in using some assembly code, which would
>bring the performance back to the 22-25% CPU usage.
>(basically what is slowing down the fp->int conversion is
try looking very, very carefully at the code ed posted here or on
csound-list a year or so ago when he optimized the "oscillates" test
program for the x86. he didn't revert to assembler, but he got an
indecent amount of speedup (my recollection is that my system went
from about 45 oscillators to several hundred or something like that).
if you want to look at the code and don't have it, let me know and
i'll post the 3 or so iterations he posted.
--p
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