static public void ReorderArray(double[] data)
{
Debug.Assert(data != null);
int length = data.Length / 2;
Debug.Assert(FourierUtils.IsPowerOf2(length) == true);
Debug.Assert(length >= cMinLength);
Debug.Assert(length <= cMaxLength);
int[] reversedBits = FourierUtils.GetReversedBits(FourierUtils.Log2(length));
for (int i = 0; i < length; i++)
{
int swap = reversedBits[i];
if (swap > i)
{
FourierUtils.Swap(ref data[i << 1], ref data[swap << 1]);
FourierUtils.Swap(ref data[i << 1 + 1], ref data[swap << 1 + 1]);
}
}
}
static public void ReorderArray(ComplexF[] data)
{
Debug.Assert(data != null);
int length = data.Length;
Debug.Assert(FourierUtils.IsPowerOf2(length) == true);
Debug.Assert(length >= cMinLength);
Debug.Assert(length <= cMaxLength);
int[] reversedBits = FourierUtils.GetReversedBits(FourierUtils.Log2(length));
for (int i = 0; i < length; i++)
{
int swap = reversedBits[i];
if (swap > i)
{
ComplexF temp = data[i];
data[i] = data[swap];
data[swap] = temp;
}
}
}
static public int[] GetReversedBits(int numberOfBits)
{
Debug.Assert(numberOfBits >= cMinBits);
Debug.Assert(numberOfBits <= cMaxBits);
if (_reversedBits[numberOfBits - 1] == null)
{
int maxBits = FourierUtils.Pow2(numberOfBits);
int[] reversedBits = new int[maxBits];
for (int i = 0; i < maxBits; i++)
{
int oldBits = i;
int newBits = 0;
for (int j = 0; j < numberOfBits; j++)
{
newBits = (newBits << 1) | (oldBits & 1);
oldBits = (oldBits >> 1);
}
reversedBits[i] = newBits;
}
_reversedBits[numberOfBits - 1] = reversedBits;
}
return(_reversedBits[numberOfBits - 1]);
}