+ Performs an atomic compare exchange operation on the 64-bit unsigned integer specified \r
+ by Value. If Value is equal to CompareValue, then Value is set to ExchangeValue and \r
+ CompareValue is returned. If Value is not equal to CompareValue, then Value is returned. \r
+ The compare exchange operation must be performed using MP safe mechanisms.\r
+\r
+ If Value is NULL, then ASSERT().\r
+\r