Org.BouncyCastle.Crypto.Engines.RC532Engine.SetKey C# (CSharp) Method

        private void SetKey(
            byte[] key)
        {
            //
            // KEY EXPANSION:
            //
            // There are 3 phases to the key expansion.
            //
            // Phase 1:
            //   Copy the secret key K[0...b-1] into an array L[0..c-1] of
            //   c = ceil(b/u), where u = 32/8 in little-endian order.
            //   In other words, we fill up L using u consecutive key bytes
            //   of K. Any unfilled byte positions in L are zeroed. In the
            //   case that b = c = 0, set c = 1 and L[0] = 0.
            //
            int[]   L = new int[(key.Length + (4 - 1)) / 4];

            for (int i = 0; i != key.Length; i++)
            {
                L[i / 4] += (key[i] & 0xff) << (8 * (i % 4));
            }

            //
            // Phase 2:
            //   Initialize S to a particular fixed pseudo-random bit pattern
            //   using an arithmetic progression modulo 2^wordsize determined
            //   by the magic numbers, Pw & Qw.
            //
            _S            = new int[2*(_noRounds + 1)];

            _S[0] = P32;
            for (int i=1; i < _S.Length; i++)
            {
                _S[i] = (_S[i-1] + Q32);
            }

            //
            // Phase 3:
            //   Mix in the user's secret key in 3 passes over the arrays S & L.
            //   The max of the arrays sizes is used as the loop control
            //
            int iter;

            if (L.Length > _S.Length)
            {
                iter = 3 * L.Length;
            }
            else
            {
                iter = 3 * _S.Length;
            }

            int A = 0, B = 0;
            int ii = 0, jj = 0;

            for (int k = 0; k < iter; k++)
            {
                A = _S[ii] = RotateLeft(_S[ii] + A + B, 3);
                B =  L[jj] = RotateLeft( L[jj] + A + B, A+B);
                ii = (ii+1) % _S.Length;
                jj = (jj+1) %  L.Length;
            }
        }