System.Data.SqlTypes.SqlDecimal.DivByULong C# (CSharp) Method

        private uint DivByULong(uint iDivisor)
        {
            ulong dwlDivisor = iDivisor;
            ulong dwlAccum = 0;           //Accumulated sum
            uint ulQuotientCur = 0;      // Value of the current UI4 of the quotient
            bool fAllZero = true;    // All of the quotient (so far) has been 0
            int iData;              //Which UI4 currently on

            // Check for zero divisor.
            if (dwlDivisor == 0)
                throw new DivideByZeroException(SQLResource.s_divideByZeroMessage);

            // Copy into array, so that we can iterate through the data
            uint[] rguiData = new uint[4] { _data1, _data2, _data3, _data4 };

            // Start from the MS UI4 of quotient, divide by divisor, placing result
            //        in quotient and carrying the remainder.
            // DWORDLONG sufficient accumulator since:
            //        Accum < Divisor <= 2^32 - 1    at start each loop
            //                                    initially,and mod end previous loop
            //        Accum*2^32 < 2^64 - 2^32
            //                                    multiply both side by 2^32 (x_dwlBaseUI4)
            //        Accum*2^32 + m_rgulData < 2^64
            //                                    rglData < 2^32
            for (iData = _bLen; iData > 0; iData--)
            {
                Debug.Assert(dwlAccum < dwlDivisor);
                dwlAccum = (dwlAccum << 32) + rguiData[iData - 1]; // dwlA*x_dwlBaseUI4 + rglData
                Debug.Assert((dwlAccum / dwlDivisor) < s_ulInt32Base);
                //Update dividend to the quotient.
                ulQuotientCur = (uint)(dwlAccum / dwlDivisor);
                rguiData[iData - 1] = ulQuotientCur;
                //Remainder to be carried to the next lower significant byte.
                dwlAccum = dwlAccum % dwlDivisor;

                // While current part of quotient still 0, reduce length
                if (fAllZero && (ulQuotientCur == 0))
                {
                    _bLen--;
                }
                else
                {
                    fAllZero = false;
                }
            }

            StoreFromWorkingArray(rguiData);

            // If result is 0, preserve sign but set length to 5
            if (fAllZero)
                _bLen = 1;

            AssertValid();

            // return the remainder
            Debug.Assert(dwlAccum < s_ulInt32Base);
            return (uint)dwlAccum;
        }

        private static SqlDecimal Round(SqlDecimal n, int lPosition, bool fTruncate)
        {
            if (n.IsNull)
                return SqlDecimal.Null;

            if (lPosition >= 0)
            {
                //If round to the right of decimal number
                lPosition = Math.Min(s_NUMERIC_MAX_PRECISION, lPosition);
                if (lPosition >= n.m_bScale)
                    return n;   //No need to round
            }
            else
            {
                //If round to the left of the decimal point
                lPosition = Math.Max(-s_NUMERIC_MAX_PRECISION, lPosition);

                //Return +0.00 if truncation of integer part
                if (lPosition < n.m_bScale - n.m_bPrec)
                {
                    n.SetToZero();
                    return n;
                }
            }

            uint ulRem = 0;                                         // Remainder: the highest significant digit to be truncated
            int lAdjust = Math.Abs(lPosition - (int)n.m_bScale);    // Precision adjustment
            uint ulLastDivBase = 1;                                 //

            //Compute the integral part of the numeric
            while (lAdjust > 0)
            {
                if (lAdjust >= 9)
                {
                    ulRem = n.DivByULong(s_rgulShiftBase[8]);
                    ulLastDivBase = s_rgulShiftBase[8];
                    lAdjust -= 9;
                }
                else
                {
                    ulRem = n.DivByULong(s_rgulShiftBase[lAdjust - 1]);
                    ulLastDivBase = s_rgulShiftBase[lAdjust - 1];
                    lAdjust = 0;
                }
            }

            // The rounding only depends on the first digit after the rounding position
            if (ulLastDivBase > 1)
            {
                ulRem /= (ulLastDivBase / 10);
            }

            //If result is zero, return
            if (n.FZero() && (fTruncate || ulRem < 5))
            {
                n.SetPositive();
                n.AssertValid();
                return n;
            }

            // Adjust by adding 1 if remainder is larger than 5
            if (ulRem >= 5 && !fTruncate)
                n.AddULong(1);

            // Convert back to original scale
            lAdjust = Math.Abs(lPosition - n.m_bScale);

            while (lAdjust-- > 0)
            {
                n.MultByULong(s_ulBase10);
            }

            n.AssertValid();
            return n;
        }