Subject: Re: [linux-audio-dev] Re: [linux-audio-user] Bandlimited oscillator plugins for LADSPA ('blop-0.1.0')
From: Steve Harris (S.W.Harris_AT_ecs.soton.ac.uk)
Date: Fri May 17 2002 - 17:26:53 EEST
On Fri, May 17, 2002 at 02:37:02 +0100, mike rawes wrote:
> frequencies. I was thinking of using a lookup table
> too, using some multiple of (long)frequency as key.
Why are you indexing on frequency?
> My understanding of cubic splines is fairly poor, so I
> don't know how to improve this (yet). I've used the
> code from the musicdsp archives. Applying algrebraic
> methods to reduce the number of multiplies is the best
> I can do right now.
The ones from mdsp should be fine.
I measure the cpu use using asm/msr.h from the kernel, but there is a
more portable way IIRC. I think this hack came from Paul orginally.
eg.
long long then, now, diff;
for (i=0; i<1000; i++) {
rdtscll(then);
for (j=0; j<64; j++, i++) {
INNER LOOP
}
rdtscll(now);
diff = (now - then) / 64;
if (diff < min_cyc) {
min_cyc = diff;
}
}
- Steve
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