Function float_to_half_full

SampleFramework12/v1.00/TinyEXR.cpp:6676–6711

}

FP16 float_to_half_full(FP32 f) {
  FP16 o = {0};

  // Based on ISPC reference code (with minor modifications)
  if (f.s.Exponent == 0) // Signed zero/denormal (which will underflow)
    o.s.Exponent = 0;
  else if (f.s.Exponent == 255) // Inf or NaN (all exponent bits set)
  {
    o.s.Exponent = 31;
    o.s.Mantissa = f.s.Mantissa ? 0x200 : 0; // NaN->qNaN and Inf->Inf
  } else                                 // Normalized number
  {
    // Exponent unbias the single, then bias the halfp
    int newexp = f.s.Exponent - 127 + 15;
    if (newexp >= 31) // Overflow, return signed infinity
      o.s.Exponent = 31;
    else if (newexp <= 0) // Underflow
    {
      if ((14 - newexp) <= 24) // Mantissa might be non-zero
      {
        unsigned int mant = f.s.Mantissa | 0x800000; // Hidden 1 bit
        o.s.Mantissa = mant >> (14 - newexp);
        if ((mant >> (13 - newexp)) & 1) // Check for rounding
          o.u++; // Round, might overflow into exp bit, but this is OK
      }
    } else {
      o.s.Exponent = newexp;
      o.s.Mantissa = f.s.Mantissa >> 13;
      if (f.s.Mantissa & 0x1000) // Check for rounding
        o.u++;                 // Round, might overflow to inf, this is OK
    }
  }

  o.s.Sign = f.s.Sign;
  return o;
}

// NOTE: From OpenEXR code
// #define IMF_INCREASING_Y  0