64-bit quantaties

What's "best" type to use to guarantee a 64-bit quantity? I know it's implementation and platform dependent, but is their any sort of de facto standard? I've seen int64_t, __int64, int64...

Also, on a somewhat unrelated note, do 64-bit architectures generally supply primitive types longer than 64 bits?

Answering my own question, it seems that int64_t is the correct choice, as of C99. Second question still stands, though.

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Originally Posted by pdc

Also, on a somewhat unrelated note, do 64-bit architectures generally supply primitive types longer than 64 bits?

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I suppose it all depends on the architecture, but FWIW...

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Registers

The IA-64 architecture includes a very generous complement of registers: 128 each of 82-bit floating point and 64-bit integer registers.

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I think "long long" is the long-long-winded, yet correct choice. Might as well typedef it away.