Function readExponent

ext/src/llvm/APFloat.cpp:239–280

Return the value of a decimal exponent of the form [+-]ddddddd. If the exponent overflows, returns a large exponent with the appropriate sign. */

   If the exponent overflows, returns a large exponent with the
   appropriate sign.  */
static Expected<int> readExponent(StringRef::iterator begin,
                                  StringRef::iterator end) {
  bool isNegative;
  unsigned int absExponent;
  const unsigned int overlargeExponent = 24000;  /* FIXME.  */
  StringRef::iterator p = begin;

  // Treat no exponent as 0 to match binutils
  if (p == end || ((*p == '-' || *p == '+') && (p + 1) == end)) {
    return 0;
  }

  isNegative = (*p == '-');
  if (*p == '-' || *p == '+') {
    p++;
    if (p == end)
      return createError("Exponent has no digits");
  }

  absExponent = decDigitValue(*p++);
  if (absExponent >= 10U)
    return createError("Invalid character in exponent");

  for (; p != end; ++p) {
    unsigned int value;

    value = decDigitValue(*p);
    if (value >= 10U)
      return createError("Invalid character in exponent");

    absExponent = absExponent * 10U + value;
    if (absExponent >= overlargeExponent) {
      absExponent = overlargeExponent;
      break;
    }
  }

  if (isNegative)
    return -(int) absExponent;
  else
    return (int) absExponent;
}

/* This is ugly and needs cleaning up, but I don't immediately see
   how whilst remaining safe.  */