public static void ComputeButterfly(int resolution, int numButterflies, out int[][] indices, out float[][] weights)
{
indices = new int[numButterflies][];
weights = new float[numButterflies][];
for (int i = 0; i < numButterflies; i++)
{
indices[i] = new int[resolution << 1];
weights[i] = new float[resolution << 1];
}
ButterflyFFTUtility.ComputeIndices(indices, resolution, numButterflies);
ButterflyFFTUtility.ComputeWeights(weights, resolution, numButterflies);
}
private static void ComputeIndices(int[][] indices, int resolution, int numButterflies)
{
int num = resolution;
int num2 = 1;
for (int i = 0; i < numButterflies; i++)
{
num >>= 1;
int num3 = num << 1;
int num4 = 0;
int num5 = 0;
int num6 = num3;
int[] array = indices[i];
for (int j = 0; j < num2; j++)
{
int k = num5;
int num7 = num4;
int num8 = 0;
while (k < num6)
{
array[k] = num7;
array[k + 1] = num7 + num;
array[num8 + num6] = num7;
array[num8 + num6 + 1] = num7 + num;
k += 2;
num8 += 2;
num7++;
}
num5 += num3 << 1;
num6 += num3 << 1;
num4 += num3;
}
num2 <<= 1;
}
ButterflyFFTUtility.BitReverse(indices[numButterflies - 1], resolution << 1, numButterflies);
}
