128 bit signed and unsigned integer types

[Martin d'Anjou]

> template FixedInt(uint n) if (n == 8) { alias byte FixedInt; }
> template FixedInt(uint n) if (n == 16) { alias short FixedInt; }
> template FixedInt(uint n) if (n == 32) { alias int FixedInt; }
> template FixedInt(uint n) if (n == 64) { alias long FixedInt; }

Where can I find FixedInt for generic values of n? I assume FixedInt will 
not resize itself ever. Perfect for emulating hardware/CPU registers of 
arbitrary size.

Martin