glhlib
"glh" stands for Graphics Library Helper.
...The optimizations are done with assembly and are for the x86 architecture. For Win32. For VC++6. It compiles and makes a DLL (and a .LIB for VC++6). The release version of the .H file is also included.
Nothing stops you from using these functions in D3D. Actually, GLHLIB doesn't use any OpenGL functions.