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

			public static BigInteger [] multiByteDivide (BigInteger bi1, BigInteger bi2)
			{
				if (Kernel.Compare (bi1, bi2) == Sign.Negative)
					return new BigInteger [2] { 0, new BigInteger (bi1) };

				bi1.Normalize (); bi2.Normalize ();

				if (bi2.length == 1)
					return DwordDivMod (bi1, bi2.data [0]);

				uint remainderLen = bi1.length + 1;
				int divisorLen = (int)bi2.length + 1;

				uint mask = 0x80000000;
				uint val = bi2.data [bi2.length - 1];
				int shift = 0;
				int resultPos = (int)bi1.length - (int)bi2.length;

				while (mask != 0 && (val & mask) == 0) {
					shift++; mask >>= 1;
				}

				BigInteger quot = new BigInteger (Sign.Positive, bi1.length - bi2.length + 1);
				BigInteger rem = (bi1 << shift);

				uint [] remainder = rem.data;

				bi2 = bi2 << shift;

				int j = (int)(remainderLen - bi2.length);
				int pos = (int)remainderLen - 1;

				uint firstDivisorByte = bi2.data [bi2.length-1];
				ulong secondDivisorByte = bi2.data [bi2.length-2];

				while (j > 0) {
					ulong dividend = ((ulong)remainder [pos] << 32) + (ulong)remainder [pos-1];

					ulong q_hat = dividend / (ulong)firstDivisorByte;
					ulong r_hat = dividend % (ulong)firstDivisorByte;

					do {

						if (q_hat == 0x100000000 ||
							(q_hat * secondDivisorByte) > ((r_hat << 32) + remainder [pos-2])) {
							q_hat--;
							r_hat += (ulong)firstDivisorByte;

							if (r_hat < 0x100000000)
								continue;
						}
						break;
					} while (true);

					//
					// At this point, q_hat is either exact, or one too large
					// (more likely to be exact) so, we attempt to multiply the
					// divisor by q_hat, if we get a borrow, we just subtract
					// one from q_hat and add the divisor back.
					//

					uint t;
					uint dPos = 0;
					int nPos = pos - divisorLen + 1;
					ulong mc = 0;
					uint uint_q_hat = (uint)q_hat;
					do {
						mc += (ulong)bi2.data [dPos] * (ulong)uint_q_hat;
						t = remainder [nPos];
						remainder [nPos] -= (uint)mc;
						mc >>= 32;
						if (remainder [nPos] > t) mc++;
						dPos++; nPos++;
					} while (dPos < divisorLen);

					nPos = pos - divisorLen + 1;
					dPos = 0;

					// Overestimate
					if (mc != 0) {
						uint_q_hat--;
						ulong sum = 0;

						do {
							sum = ((ulong)remainder [nPos]) + ((ulong)bi2.data [dPos]) + sum;
							remainder [nPos] = (uint)sum;
							sum >>= 32;
							dPos++; nPos++;
						} while (dPos < divisorLen);

					}

					quot.data [resultPos--] = (uint)uint_q_hat;

					pos--;
					j--;
				}

				quot.Normalize ();
				rem.Normalize ();
				BigInteger [] ret = new BigInteger [2] { quot, rem };

				if (shift != 0)
					ret [1] >>= shift;

				return ret;
			}