128 bit signed and unsigned integer types

[dsimcha]

== Quote from Andrei Alexandrescu (SeeWebsiteForEmail at erdani.org)'s article
> Walter Bright wrote:
> > John Reimer wrote:
> >> Hello Walter,
> >>
> >>> You know, the unimplemented 128 bit integer types.
> >>>
> >>> Does anyone have a use for these?
> >>>
> >>
> >>
> >> Was that "cent" and "ucent"?
> >
> > yes.
> >
> >> Would any of these map well to SSE Instructions on Intel CPU's?
> >
> > Not a chance :-(
> Then it looks like we better leave large fixed-size integers to a library.
> Andrei

Something that I still don't think has been made very clear in this discussion
that I'm very curious about:  How efficient would these large fixed-size ints be
(on 32-bit hardware)?  Would they be almost as fast as 64-bit, almost as slow as
bigints, or somewhere roughly in the middle?  Obviously on 64-bit hardware they
can be made fast, but if that's the only place they can be made fast, then I think
it's more important that DMD support 64-bit hardware first.