tdf#96918 display accurate integer double values up to (2^53)-1
Change-Id: I42001583c72bc3faab94489a4eabfa183cab5ae2
diff --git a/sal/rtl/math.cxx b/sal/rtl/math.cxx
index be8ebbe..45d07b7 100644
--- a/sal/rtl/math.cxx
+++ b/sal/rtl/math.cxx
@@ -207,6 +207,73 @@ inline void doubleToString(StringT ** pResult,
return;
}
// Use integer representation for integer values that fit into the
// mantissa (1.((2^53)-1)) with a precision of 1 for highest accuracy.
const sal_Int64 kMaxInt = (static_cast<sal_Int64>(1) << 53) - 1;
if ((eFormat == rtl_math_StringFormat_Automatic ||
eFormat == rtl_math_StringFormat_F) && fValue <= static_cast<double>(kMaxInt))
{
sal_Int64 nInt = static_cast<sal_Int64>(fValue);
// Check the integer range again because double comparison may yield
// true within the precision range.
if (nInt <= kMaxInt && static_cast<double>(nInt) == fValue)
{
if (nDecPlaces == rtl_math_DecimalPlaces_Max || bEraseTrailingDecZeros)
nDecPlaces = 0;
else
nDecPlaces = ::std::min( nDecPlaces, 15);
// Max 1 sign, 16 integer digits, 15 group separators, 1 decimal
// separator, 15 decimals digits.
typename T::Char aBuf[64];
typename T::Char * pBuf = aBuf;
typename T::Char * p = pBuf;
// Backward fill.
size_t nGrouping = 0;
sal_Int32 nGroupDigits = 0;
do
{
typename T::Char nDigit = nInt % 10;
nInt /= 10;
*p++ = nDigit + '0';
if (pGroups && pGroups[nGrouping] == ++nGroupDigits && nInt > 0 && cGroupSeparator)
{
*p++ = cGroupSeparator;
if (pGroups[nGrouping+1])
++nGrouping;
nGroupDigits = 0;
}
}
while (nInt > 0);
if (bSign)
*p++ = '-';
// Reverse buffer content.
sal_Int32 n = (p - pBuf) / 2;
for (sal_Int32 i=0; i < n; ++i)
{
typename T::Char c = p[-i-1];
p[-i-1] = pBuf[i];
pBuf[i] = c;
}
// Append decimals.
if (nDecPlaces)
{
*p++ = cDecSeparator;
while (nDecPlaces--)
*p++ = '0';
}
if (pResultCapacity == nullptr)
T::createString(pResult, pBuf, p - pBuf);
else
T::appendChars(pResult, pResultCapacity, &nResultOffset, pBuf, p - pBuf);
return;
}
}
// find the exponent
int nExp = 0;
if ( fValue > 0.0 )
