diff options
Diffstat (limited to 'lib/Support')
| -rw-r--r-- | lib/Support/APFloat.cpp | 26 |
1 files changed, 26 insertions, 0 deletions
diff --git a/lib/Support/APFloat.cpp b/lib/Support/APFloat.cpp index 9f5ca3e..2139df5 100644 --- a/lib/Support/APFloat.cpp +++ b/lib/Support/APFloat.cpp @@ -1765,6 +1765,32 @@ APFloat::fusedMultiplyAdd(const APFloat &multiplicand, return fs; } +/* Rounding-mode corrrect round to integral value. */ +APFloat::opStatus APFloat::roundToIntegral(roundingMode rounding_mode) { + opStatus fs; + assertArithmeticOK(*semantics); + + // The algorithm here is quite simple: we add 2^(p-1), where p is the + // precision of our format, and then subtract it back off again. The choice + // of rounding modes for the addition/subtraction determines the rounding mode + // for our integral rounding as well. + APInt IntegerConstant(NextPowerOf2(semanticsPrecision(*semantics)), + 1 << (semanticsPrecision(*semantics)-1)); + APFloat MagicConstant(*semantics); + fs = MagicConstant.convertFromAPInt(IntegerConstant, false, + rmNearestTiesToEven); + if (fs != opOK) + return fs; + + fs = add(MagicConstant, rounding_mode); + if (fs != opOK && fs != opInexact) + return fs; + + fs = subtract(MagicConstant, rounding_mode); + return fs; +} + + /* Comparison requires normalized numbers. */ APFloat::cmpResult APFloat::compare(const APFloat &rhs) const |