InterlockedCompareExchange function
Compares the input to the comparison value and exchanges the result, atomically.
Syntax
void InterlockedCompareExchange(
in UINT dest,
in UINT compare_value,
in UINT value,
out UINT original_value
);
Parameters
-
dest [in]
-
Type: UINT
The destination address.
-
compare_value [in]
-
Type: UINT
The comparison value.
-
value [in]
-
Type: UINT
The input value.
-
original_value [out]
-
Type: UINT
The original value.
Return value
This function does not return a value.
Remarks
Atomically compares the value in dest to compare_value, stores value in dest if the values match, returns the original value of dest in original_value. This operation can only be performed on int or uint typed resources and shared memory variables. There are three possible uses for this function. The first is when R is a shared memory variable type. In this case, the function performs the operation on the shared memory register referenced by dest. The second scenario is when R is a resource variable type. In this scenario, the function performs the operation on the resource location referenced by dest. Finally, the third scenario is when R is a local variable type. In this scenario, the function reduces to the operation performed using local operations. This operation is only available when R is readable and writable.
Note
If you call InterlockedCompareExchange in a for or while compute shader loop, to properly compile, you must use the [allow_uav_condition] attribute on that loop.
This function is supported in the following types of shaders:
| VS | HS | DS | GS | PS | CS |
|---|---|---|---|---|---|
| x | x | x | x | x | x |
See also