Method toString

ext/src/llvm/APFloat.cpp:3689–3903

}

void IEEEFloat::toString(SmallVectorImpl<char> &Str, unsigned FormatPrecision,
                         unsigned FormatMaxPadding, bool TruncateZero) const {
  switch (category) {
  case fcInfinity:
    if (isNegative())
      return append(Str, "-Inf");
    else
      return append(Str, "+Inf");

  case fcNaN: return append(Str, "NaN");

  case fcZero:
    if (isNegative())
      Str.push_back('-');

    if (!FormatMaxPadding) {
      if (TruncateZero)
        append(Str, "0.0E+0");
      else {
        append(Str, "0.0");
        if (FormatPrecision > 1)
          Str.append(FormatPrecision - 1, '0');
        append(Str, "e+00");
      }
    } else
      Str.push_back('0');
    return;

  case fcNormal:
    break;
  }

  if (isNegative())
    Str.push_back('-');

  // Decompose the number into an APInt and an exponent.
  int exp = exponent - ((int) semantics->precision - 1);
  APInt significand(semantics->precision,
                    makeArrayRef(significandParts(),
                                 partCountForBits(semantics->precision)));

  // Set FormatPrecision if zero.  We want to do this before we
  // truncate trailing zeros, as those are part of the precision.
  if (!FormatPrecision) {
    // We use enough digits so the number can be round-tripped back to an
    // APFloat. The formula comes from "How to Print Floating-Point Numbers
    // Accurately" by Steele and White.
    // FIXME: Using a formula based purely on the precision is conservative;
    // we can print fewer digits depending on the actual value being printed.

    // FormatPrecision = 2 + floor(significandBits / lg_2(10))
    FormatPrecision = 2 + semantics->precision * 59 / 196;
  }

  // Ignore trailing binary zeros.
  int trailingZeros = significand.countTrailingZeros();
  exp += trailingZeros;
  significand.lshrInPlace(trailingZeros);