/// <summary>
/// FFT cache constructor.
/// </summary>
public FFTCache(int size)
{
if (CavernAmp.Available)
{
Native = CavernAmp.FFTCache_Create(size);
return;
}
int halfSize = size / 2;
double step = -2 * Math.PI / size;
cos = new float[halfSize];
sin = new float[halfSize];
for (int i = 0; i < halfSize; ++i)
{
double rotation = i * step;
cos[i] = (float)Math.Cos(rotation);
sin[i] = (float)Math.Sin(rotation);
}
for (int depth = 0, maxDepth = QMath.Log2(size); depth < maxDepth; ++depth)
{
if (Even[depth] == null)
{
Even[depth] = new Complex[1 << depth];
Odd[depth] = new Complex[1 << depth];
}
}
}
public static void InPlaceFFT(this Complex[] samples, FFTCache cache)
{
if (CavernAmp.Available)
{
CavernAmp.InPlaceFFT(samples, cache);
}
else
{
ProcessFFT(samples, cache, QMath.Log2(samples.Length) - 1);
}
}
/// <summary>
/// Inverse Fast Fourier Transform of a transformed signal, while keeping the source array allocation.
/// </summary>
public static void InPlaceIFFT(this Complex[] samples, FFTCache cache)
{
if (CavernAmp.Available)
{
CavernAmp.InPlaceIFFT(samples, cache);
return;
}
ProcessIFFT(samples, cache, QMath.Log2(samples.Length) - 1);
float multiplier = 1f / samples.Length;
for (int i = 0; i < samples.Length; ++i)
{
samples[i].Real *= multiplier;
samples[i].Imaginary *= multiplier;
}
}
/// <summary>
/// Apply a delay on the <paramref name="signal"/> even with fraction <paramref name="samples"/>.
/// </summary>
public static void Delay(float[] signal, float samples)
{
using FFTCache cache = new FFTCache(QMath.Base2Ceil(signal.Length));
Delay(signal, samples);
}
