_InterlockedCompareExchange64_rel

 Same as the _InterlockedCompareExchange_rel function, except that
 those parts of the algorithm that are marked "Atomic" are performed
 by the cmpxchg8.rel instruction.

 Syntax:

      unsigned __int64 _InterlockedCompareExchange64_rel (volatile 
      unsigned int64 *Destination, unsigned __int64 Newval, unsigned
      __int64 Comparand);