Resolves: tdf#136272 convert DBL_MAX to 1.7976931348623157e+308
... and the 4 subsequent nextafters to appropriate strings.
An interim workaround to not write the out-of-range string
1.79769313486232e+308 until we have a proper rounding.
Change-Id: I5f98a7f0a8e0421fd024a8cc37cc6f3a198d02d1
Reviewed-on: https://gerrit.libreoffice.org/c/core/+/106717
Tested-by: Jenkins
Reviewed-by: Eike Rathke <erack@redhat.com>
diff --git a/sal/rtl/math.cxx b/sal/rtl/math.cxx
index c58c646..7d46c75 100644
--- a/sal/rtl/math.cxx
+++ b/sal/rtl/math.cxx
@@ -274,6 +274,84 @@ void doubleToString(typename T::String ** pResult,
return;
}
// Unfortunately the old rounding below writes 1.79769313486232e+308 for
// DBL_MAX and 4 subsequent nextafter(...,0).
static const double fB1 = std::nextafter( DBL_MAX, 0);
static const double fB2 = std::nextafter( fB1, 0);
static const double fB3 = std::nextafter( fB2, 0);
static const double fB4 = std::nextafter( fB3, 0);
if ((fValue >= fB4) && eFormat != rtl_math_StringFormat_F)
{
// 1.7976931348623157e+308 instead of rounded 1.79769313486232e+308
// that can't be converted back as out of range. For rounded values if
// they exceed range they should not be written to exchange strings or
// file formats.
// Writing pDig up to decimals(-1,-2) then appending one digit from
// pRou xor one or two digits from pSlot[].
constexpr char pDig[] = "7976931348623157";
constexpr char pRou[] = "8087931459623267"; // the only up-carry is 80
static_assert(SAL_N_ELEMENTS(pDig) == SAL_N_ELEMENTS(pRou), "digit count mismatch");
constexpr sal_Int32 nDig2 = SAL_N_ELEMENTS(pRou) - 2;
sal_Int32 nCapacity = RTL_CONSTASCII_LENGTH(pRou) + 8; // + "-1.E+308"
const char pSlot[5][2][3] =
{ // rounded, not
"67", "57", // DBL_MAX
"65", "55",
"53", "53",
"51", "51",
"59", "49",
};
if (!pResultCapacity)
{
pResultCapacity = &nCapacity;
T::createBuffer(pResult, pResultCapacity);
nResultOffset = 0;
}
if (bSign)
T::appendAscii(pResult, pResultCapacity, &nResultOffset,
RTL_CONSTASCII_STRINGPARAM("-"));
nDecPlaces = std::clamp<sal_Int32>( nDecPlaces, 0, SAL_N_ELEMENTS(pRou));
if (nDecPlaces == 0)
{
T::appendAscii(pResult, pResultCapacity, &nResultOffset,
RTL_CONSTASCII_STRINGPARAM("2"));
}
else
{
T::appendAscii(pResult, pResultCapacity, &nResultOffset,
RTL_CONSTASCII_STRINGPARAM("1"));
T::appendChars(pResult, pResultCapacity, &nResultOffset, &cDecSeparator, 1);
if (nDecPlaces <= 2)
{
T::appendAscii(pResult, pResultCapacity, &nResultOffset, pRou, nDecPlaces);
}
else if (nDecPlaces <= nDig2)
{
T::appendAscii(pResult, pResultCapacity, &nResultOffset, pDig, nDecPlaces - 1);
T::appendAscii(pResult, pResultCapacity, &nResultOffset, pRou + nDecPlaces - 1, 1);
}
else
{
const sal_Int32 nDec = nDecPlaces - nDig2;
nDecPlaces -= nDec;
// nDec-1 is also offset into slot, rounded(-1=0) or not(-2=1)
const size_t nSlot = ((fValue < fB3) ? 4 : ((fValue < fB2) ? 3
: ((fValue < fB1) ? 2 : ((fValue < DBL_MAX) ? 1 : 0))));
T::appendAscii(pResult, pResultCapacity, &nResultOffset, pDig, nDecPlaces - 1);
T::appendAscii(pResult, pResultCapacity, &nResultOffset, pSlot[nSlot][nDec-1], nDec);
}
}
T::appendAscii(pResult, pResultCapacity, &nResultOffset,
RTL_CONSTASCII_STRINGPARAM("E+308"));
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;
