private static double GetTableSample(EOscillatorType oscillatorType, double t)
{
switch (oscillatorType)
{
case EOscillatorType.Sine:
return(Math.Sin(DSPFunctions.Pi2 * t));
case EOscillatorType.Triangle:
if (t < 0.25)
{
return(4 * t);
}
if (t < 0.75)
{
return(2 - 4 * t);
}
return(4 * (t - 1));
case EOscillatorType.Square:
return((t < 0.5f) ? 1 : -1);
case EOscillatorType.Saw:
return(2 * t - 1);
case EOscillatorType.Noise:
return(_random.NextDouble() * 2 - 1);
default:
throw new ArgumentOutOfRangeException();
}
}
double naiveWaveformForMode(EOscillatorType mode)
{
switch (mode)
{
case EOscillatorType.Sine:
return(Math.Sin(phase));
case EOscillatorType.Saw:
return((2.0 * phase / twoPI) - 1.0);
case EOscillatorType.Square:
if (phase < Math.PI)
{
return(1.0);
}
else
{
return(-1.0);
}
case EOscillatorType.Noise:
return(_random.NextDouble() * 2 - 1);
default:
throw new ArgumentOutOfRangeException();
}
}
private static double GenerateNextSample(EOscillatorType oscillatorType, double frequency, double time)
{
var ph = time * frequency;
ph -= (int)ph;
return(GetTableSample(oscillatorType, ph));
}
public Oscillator(AudioProcessor audioProcessor, OscParameters paramOwner, int note, double detune, double phase) :
base(audioProcessor)
{
audioProcessor.OnSampleRateChanged += SampleRateChanged;
paramOwner.OscillatorType.OnValueChange += TypeChanged;
type = paramOwner.OscillatorType.Value;
calc = twoPI / Processor.SampleRate;
this.note = note;
this.phase = phase;
this.detune = detune;
this.paramOwner = paramOwner;
}
void SetOsc(float baseFreq, EOscillatorType osctype)
{
ClearWaveTable();
var sampleRate = paramOwner.Processor.SampleRate;
// calc number of harmonics where the highest harmonic baseFreq and lowest alias an octave higher would meet
int maxHarms = (int)(sampleRate / (3.0 * baseFreq) + 0.5);
// round up to nearest power of two
uint v = (uint)maxHarms;
v--; // so we don't go up if already a power of 2
v |= v >> 1; // roll the highest bit into all lower bits...
v |= v >> 2;
v |= v >> 4;
v |= v >> 8;
v |= v >> 16;
v++; // and increment to power of 2
int tableLen = (int)(v * 2 * overSamp); // double for the sample rate, then oversampling
double[] ar = new double[tableLen]; // for ifft
double[] ai = new double[tableLen];
double topFreq = baseFreq * 2.0 / sampleRate;
double scale = 0.0;
for (; maxHarms >= 1; maxHarms >>= 1)
{
if (osctype == EOscillatorType.Saw)
{
DefineSawtooth(tableLen, maxHarms, ar, ai);
}
else if (osctype == EOscillatorType.Triangle)
{
DefineTriangle(tableLen, maxHarms, ar, ai);
}
else if (osctype == EOscillatorType.Square)
{
DefineSquare(tableLen, maxHarms, ar, ai);
}
scale = makeWaveTable(tableLen, ar, ai, scale, topFreq);
topFreq *= 2;
if (tableLen > 99999) // variable table size (constant oversampling but with minimum table size)
{
tableLen >>= 1;
}
}
}
private void TypeChanged(Parameter.EChangeType obj)
{
type = paramOwner.OscillatorType.Value;
}
