attribute ((mode(TI)))

[Victor Shoup]

On 64-bit machines, there seems to be no standard way to
declare a 128-bit integer type, as "long long" is only 64 bits
on such machines.

I have noticed that on 64-bit machines

   typedef int really_long __attribute__ ((mode (TI)))

seems to work, but I have found no documentation that would suggest
that this is at all reliable.

So my question is, to anyone who know, is the above incantation
(and similarly for unsigned types) a fairly reliable way to get
a 128-bit type on a 64-bit machine with gcc?

Another question: are than any plans to have gcc provide a more 
"standard looking"
128-bit type in the future, e.g., a type int128_t (defined, say, in 
<stdint.h>), or some other
type name?

Thanks,
    Victor