I use `halffloat` for 16 bit floats. But be careful, there are several different encodings of 16 bit floats, so float16 isn't enough in and of itself.

SIMD types in D are done with:

    __vector(byte[16]), __vector(int[8])

and an alias (typedef for the C folk) for this is commonly used, like `byte16` and `int8`.