Org.BouncyCastle.Math.BigInteger.Square C# (CSharp) Метод

		private static int[] Square(
			int[]	w,
			int[]	x)
		{
			// Note: this method allows w to be only (2 * x.Length - 1) words if result will fit
//			if (w.Length != 2 * x.Length)
//				throw new ArgumentException("no I don't think so...");

			ulong u1, u2, c;

			int wBase = w.Length - 1;

			for (int i = x.Length - 1; i != 0; i--)
			{
				ulong v = (ulong)(uint) x[i];

				u1 = v * v;
				u2 = u1 >> 32;
				u1 = (uint) u1;

				u1 += (ulong)(uint) w[wBase];

				w[wBase] = (int)(uint) u1;
				c = u2 + (u1 >> 32);

				for (int j = i - 1; j >= 0; j--)
				{
					--wBase;
					u1 = v * (ulong)(uint) x[j];
					u2 = u1 >> 31; // multiply by 2!
					u1 = (uint)(u1 << 1); // multiply by 2!
					u1 += c + (ulong)(uint) w[wBase];

					w[wBase] = (int)(uint) u1;
					c = u2 + (u1 >> 32);
				}

				c += (ulong)(uint) w[--wBase];
				w[wBase] = (int)(uint) c;

				if (--wBase >= 0)
				{
					w[wBase] = (int)(uint)(c >> 32);
				}
				else
				{
					Debug.Assert((uint)(c >> 32) == 0);
				}
				wBase += i;
			}

			u1 = (ulong)(uint) x[0];
			u1 = u1 * u1;
			u2 = u1 >> 32;
			u1 = u1 & IMASK;

			u1 += (ulong)(uint) w[wBase];

			w[wBase] = (int)(uint) u1;
			if (--wBase >= 0)
			{
				w[wBase] = (int)(uint)(u2 + (u1 >> 32) + (ulong)(uint) w[wBase]);
			}
			else
			{
				Debug.Assert((uint)(u2 + (u1 >> 32)) == 0);
			}

			return w;
		}

        private static BigInteger ModPowBarrett(BigInteger b, BigInteger e, BigInteger m)
        {
            int k = m.magnitude.Length;
            BigInteger mr = One.ShiftLeft((k + 1) << 5);
            BigInteger yu = One.ShiftLeft(k << 6).Divide(m);

            // Sliding window from MSW to LSW
            int extraBits = 0, expLength = e.BitLength;
            while (expLength > ExpWindowThresholds[extraBits])
            {
                ++extraBits;
            }

            int numPowers = 1 << extraBits;
            BigInteger[] oddPowers = new BigInteger[numPowers];
            oddPowers[0] = b;

            BigInteger b2 = ReduceBarrett(b.Square(), m, mr, yu);

            for (int i = 1; i < numPowers; ++i)
            {
                oddPowers[i] = ReduceBarrett(oddPowers[i - 1].Multiply(b2), m, mr, yu);
            }

            int[] windowList = GetWindowList(e.magnitude, extraBits);
            Debug.Assert(windowList.Length > 0);

            int window = windowList[0];
            int mult = window & 0xFF, lastZeroes = window >> 8;

            BigInteger y;
            if (mult == 1)
            {
                y = b2;
                --lastZeroes;
            }
            else
            {
                y = oddPowers[mult >> 1];
            }

            int windowPos = 1;
            while ((window = windowList[windowPos++]) != -1)
            {
                mult = window & 0xFF;

                int bits = lastZeroes + BitLengthTable[mult];
                for (int j = 0; j < bits; ++j)
                {
                    y = ReduceBarrett(y.Square(), m, mr, yu);
                }

                y = ReduceBarrett(y.Multiply(oddPowers[mult >> 1]), m, mr, yu);

                lastZeroes = window >> 8;
            }

            for (int i = 0; i < lastZeroes; ++i)
            {
                y = ReduceBarrett(y.Square(), m, mr, yu);
            }

            return y;
        }