InterlockedCompareExchange
[New
- Windows NT]
The InterlockedCompareExchange
function performs an atomic comparison of the values specified in the Destination
and Comperand parameters and exchange of the values, based on the
outcome of the comparison. The function prevents more than one thread from
using the same variable simultaneously.
PVOID InterlockedCompareExchange(
|
PVOID *Destination, |
// pointer
to the destination pointer |
|
PVOID Exchange, |
// the
exchange value |
|
PVOID Comperand |
// the
value to compare |
|
); |
|
Parameters
Destination
Specifies the
address of the destination value. This is a 32-bit value. The sign is ignored.
Exchange
Specifies the
exchange value. This is a 32-bit value. The sign is ignored.
Comperand
Specifies the
value to compare to Destination. This is a 32-bit value. The sign is
ignored.
Return Values
The return
value is the initial value of the destination.
Remarks
The functions
InterlockedCompareExchange, InterlockedDecrement, InterlockedExchange, InterlockedExchangeAdd, and InterlockedIncrement provide a simple mechanism
for synchronizing access to a variable that is shared by multiple threads. The
threads of different processes can use this mechanism if the variable is in
shared memory.
The InterlockedCompareExchange
function performs an atomic comparison of the Destination value with the
Comperand value. If the Destination value is equal to the Comperand
value, the Exchange value is stored in the address specified by Destination.
Otherwise, no operation is performed.
The variables
for InterlockedCompareExchange must be aligned on a 32-bit boundary;
otherwise, this function will fail on multiprocessor x86 systems.
See Also