Porting from M$

Hi, I don't know if this is a compiler question or a platform question but it is definitely a programming question. On the new M$ 64-bit platform released this week, they support ATOMIC operations on 64-bit values. Were do I find the equivalent ATOMIC functions on LINUX? In asm-x86_64/atomic.h I can only find operations that work on 32-bit values. Do I basically have to roll my own versions of these functions? Is this something someone is looking to add to atomic.h for various platforms? Thanks in Advance, Dennis