InterlockedCompare

Compare.cpp

/*
Syntax:
  LONG __cdecl InterlockedCompareExchange(__inout  LONG volatile *Destination,
								  			__in     LONG Exchange,
  											__in     LONG Comparand
											);
	
	Returns the initial value of 'Destination'.

Note:
To operate on 64-bit values, use the InterlockedCompareExchange64 function.
*/

LONG curr_value;
LONG new_value;
LONG seed;
cur_value = InterlockedCompareExchange(&seed, new_value, old_value);