AForge.Math.FourierTransform.GetReversedBits C# (CSharp) Method

        private static int[] GetReversedBits(int numberOfBits)
        {
            if ((numberOfBits < minBits) || (numberOfBits > maxBits))
                throw new ArgumentOutOfRangeException();

            // check if the array is already calculated
            if (reversedBits[numberOfBits - 1] == null)
            {
                int n = Tools.Pow2(numberOfBits);
                var rBits = new int[n];

                // calculate the array
                for (int i = 0; i < n; i++)
                {
                    int oldBits = i;
                    int newBits = 0;

                    for (int j = 0; j < numberOfBits; j++)
                    {
                        newBits = (newBits << 1) | (oldBits & 1);
                        oldBits = (oldBits >> 1);
                    }
                    rBits[i] = newBits;
                }
                reversedBits[numberOfBits - 1] = rBits;
            }
            return reversedBits[numberOfBits - 1];
        }