Same as the _InterlockedCompareExchange_acq function, except that
those parts of the algorithm that are marked "Atomic" are performed
by the cmpxchg8.acq instruction.
Syntax:
unsigned __int64 _InterlockedCompareExchange64_acq (volatile
unsigned int64 *Destination, unsigned __int64 Newval, unsigned
__int64 Comparand);