Graphics Reference
In-Depth Information
if (mantissa && (exp == FLOAT_MAX_BIASED_EXP))
{
// we have a single-precision NaN
mantissa = (1 << 23) − 1;
}
else
{
// 16-bit half-float representation stores number
// as Inf mantissa = 0;
}
hf = (((hfloat)sign) << 15) |
(hfloat)(HALF_FLOAT_MAX_BIASED_EXP) |
(hfloat)(mantissa >> 13);
}
// check if exponent is <= −15
else if (exp <= HALF_FLOAT_MIN_BIASED_EXP_AS_SINGLE_FP_EXP)
{
// store a denorm half-float value or zero
exp = (HALF_FLOAT_MIN_BIASED_EXP_AS_SINGLE_FP_EXP − exp)
>> 23;
mantissa >>= (14 + exp);
hf = (((hfloat)sign) << 15) | (hfloat)(mantissa);
}
else
{
hf = (((hfloat)sign) << 15) |
(hfloat)
((exp − HALF_FLOAT_MIN_BIASED_EXP_AS_SINGLE_FP_EXP)
>> 13)|
(hfloat)(mantissa >> 13);
}
return hf;
}
float
convertHFloatToFloat(hfloat hf)
{
unsigned int sign = (unsigned int)(hf >> 15);
unsigned int mantissa = (unsigned int)(hf &
((1 << 10) − 1));
unsigned int exp = (unsigned int)(hf &
HALF_FLOAT_MAX_BIASED_EXP);
unsigned int f;
if (exp == HALF_FLOAT_MAX_BIASED_EXP)
{
// we have a half-float NaN or Inf
// half-float NaNs will be converted to a single-
// precision NaN
