Mono.Math.BigInteger.Kernel.AddSameSign C# (CSharp) Method

			public static BigInteger AddSameSign (BigInteger bi1, BigInteger bi2)
			{
				uint [] x, y;
				uint yMax, xMax, i = 0;

				// x should be bigger
				if (bi1.length < bi2.length) {
					x = bi2.data;
					xMax = bi2.length;
					y = bi1.data;
					yMax = bi1.length;
				} else {
					x = bi1.data;
					xMax = bi1.length;
					y = bi2.data;
					yMax = bi2.length;
				}
				
				BigInteger result = new BigInteger (Sign.Positive, xMax + 1);

				uint [] r = result.data;

				ulong sum = 0;

				// Add common parts of both numbers
				do {
					sum = ((ulong)x [i]) + ((ulong)y [i]) + sum;
					r [i] = (uint)sum;
					sum >>= 32;
				} while (++i < yMax);

				// Copy remainder of longer number while carry propagation is required
				bool carry = (sum != 0);

				if (carry) {

					if (i < xMax) {
						do
							carry = ((r [i] = x [i] + 1) == 0);
						while (++i < xMax && carry);
					}

					if (carry) {
						r [i] = 1;
						result.length = ++i;
						return result;
					}
				}

				// Copy the rest
				if (i < xMax) {
					do
						r [i] = x [i];
					while (++i < xMax);
				}

				result.Normalize ();
				return result;
			}