A little function to speed things up a bit

[paradoxnj]

After running VTune against Jet3D, I noticed that Jet3D was spending a lot of time converting floats to DWORDs. As we all know, that is an evil operation and should have holy water sprayed all over it. Fear not, as I have exercised that demon. I wrote a small inline assembly function that converts a float to a DWORD without resetting the FPU each time. This little function gained us about 5 FPS. I noticed that Genesis has the same issue also which is why I am posting it here.

Code: Select all

inline DWORD FtoDW(float f)
{
	DWORD				d;

	_asm
	{
		fld			f
		lea			eax, [d]
		fistp		dword ptr[eax]
	}

	return d;
}

Just replace the FtoDW() function in the drivers with this and for any float to DWORD (or integer) conversions, use it.