public SDL_Timer()
{
double tfreq = 1000000.0 / FrameTicks;
loop_error = Calc.recfilter_init(tfreq, 0.1);
Calc.PFD_init(ref phase_detector, 0.0);
}
public static void recfilter_setlast(ref recfilter f, double val)
{
f.lastval = val;
if (f.peak_detect != 0)
{
_recfilter_peak_detect(ref f);
}
}
public static double recfilter_apply_int(ref recfilter f, int x)
{
f.lastval = f.a * (double)(x) + f.b * f.lastval;
if (f.peak_detect != 0)
{
_recfilter_peak_detect(ref f);
}
return(f.lastval);
}
public static double recfilter_apply(ref recfilter f, double x)
{
f.lastval = f.a * x + f.b * f.lastval;
if (f.peak_detect != 0)
{
_recfilter_peak_detect(ref f);
}
return(f.lastval);
}
private static void _recfilter_peak_detect(ref recfilter f)
{
if (f.lastval > f.maxval)
{
f.maxval = f.lastval;
}
if (f.lastval < f.minval)
{
f.minval = f.maxval;
}
}
public static recfilter recfilter_init(double Fs, double Fc)
{
recfilter f = new recfilter();
if (Fs < Fc * 2.0)
{
throw new InvalidOperationException($"recfilter_init: cutoff frequency ({Fc:N1}) should be less than half of the sampling rate ({Fs:N1})");
}
f.b = Math.Exp(-2.0 * Math.PI * Fc / Fs);
f.a = 1.0 - f.b;
return(f);
}
public static void recfilter_peak_detect(ref recfilter f)
{
f.peak_detect = 1;
f.maxval = f.lastval;
f.minval = f.lastval;
}
public static double recfilter_getlast(ref recfilter f)
{
return(f.lastval);
}
