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; }