Algorithm scryptROMix

Input:
        r       Block size parameter.
        B       Input octet vector of length 128 * r octets.
        N       CPU/Memory cost parameter, must be larger than 1,
                a power of 2 and less than 2^(128 * r / 8).

Output:
        B'      Output octet vector of length 128 * r octets.

Steps:

 1. X = B

 2. for i = 0 to N - 1 do
      V[i] = X
      X = scryptBlockMix (X)
    end for

 3. for i = 0 to N - 1 do
      j = Integerify (X) mod N
             where Integerify (B[0] ... B[2 * r - 1]) is defined
             as the result of interpreting B[2 * r - 1] as a
             little-endian integer.
      T = X xor V[j]
      X = scryptBlockMix (T)
    end for

 4. B' = X