compilter bug nighmare?
compilter bug nighmare?
- Subject: compilter bug nighmare?
- From: Alexey Menshikov <email@hidden>
- Date: Mon, 27 Jun 2005 09:53:14 +0300
Hi,
I have a commercial project - audio plug-ins (VST).
After switching to Tiger/Xcode2.0 i decided to release new version
but the plug-in works wrongly. _Sometimes_ it does not produce audio.
That may happens after running several instances of plug-in, sometimes
it doesn't work with first instance.
That project worked on Panther - i can run the old binary but the same
project compiled on xcode2 sometimes fail.
After commenting several parts of code i found code that possible makes
it work wrong - IIR biquad filter.
But hell, it works perfectly under win32 and early xcode.
One more notice - works nice with Development target.
What do in that cases? Try to reorganize code? I havn't any compiler warnings
on that file :(
--------------------------------------- cut --------------------------------------
The code looks like this:
float coef [4 * FILTER_ORDER + 1];
float history [2 * FILTER_ORDER];
float getValue(float in)
{
unsigned int i;
float *hist1_ptr, *hist2_ptr, *coef_ptr;
float xout, new_hist, history1, history2;
coef_ptr = coef; // coefficient pointer
hist1_ptr = history; // first history
hist2_ptr = hist1_ptr + 1; // next history
// 1st number of coefficients array is overall input scale factor, * or filter gain
xout = in * (*coef_ptr++);
for (i = 0; i < length; i++)
{
history1 = *hist1_ptr;
history2 = *hist2_ptr;
xout = xout - history1 * (*coef_ptr++);
new_hist = xout - history2 * (*coef_ptr++); // poles
xout = new_hist + history1 * (*coef_ptr++);
xout = xout + history2 * (*coef_ptr++); // zeros
*hist2_ptr++ = *hist1_ptr;
*hist1_ptr++ = new_hist;
hist1_ptr++;
hist2_ptr++;
}
return xout;
}
I used "return in;" and it worked so i suspect the bug somewhere up
there :)
--------------------------------------------
Alexey Menshikov
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