Is there a 128-bit integer in D?

[Saurabh Das via Digitalmars-d-learn]

I see that 'cent' and 'ucent' are reserved for future use but not 
yet implemented. Does anyone have a working implementation of 
these types?

Alternatively, is there an any effort towards implementation of 
arbitrary-sized integers in Phobos?

Thanks,
Saurabh