Function ilHalfToFloat

DevIL/src-IL/src/il_manip.cpp:157–221

Taken from OpenEXR

// Taken from OpenEXR
INLINE ILuint ILAPIENTRY ilHalfToFloat (ILushort y) {

	int s = (y >> 15) & 0x00000001;
	int e = (y >> 10) & 0x0000001f;
	int m =  y		  & 0x000003ff;

	if (e == 0)
	{
		if (m == 0)
		{
			//
			// Plus or minus zero
			//

			return s << 31;
		}
		else
		{
			//
			// Denormalized number -- renormalize it
			//

			while (!(m & 0x00000400))
			{
				m <<= 1;
				e -=  1;
			}

			e += 1;
			m &= ~0x00000400;
		}
	}
	else if (e == 31)
	{
		if (m == 0)
		{
			//
			// Positive or negative infinity
			//

			return (s << 31) | 0x7f800000;
		}
		else
		{
			//
			// Nan -- preserve sign and significand bits
			//

			return (s << 31) | 0x7f800000 | (m << 13);
		}
	}

	//
	// Normalized number
	//

	e = e + (127 - 15);
	m = m << 13;