InterlockedCompareExchangePointerAcquire function
Performs an atomic compare-and-exchange operation on the specified values. The function compares two specified pointer values and exchanges with another pointer value based on the outcome of the comparison. The operation is performed with acquire memory access semantics.
Syntax
PVOID __cdecl InterlockedCompareExchangePointerAcquire( __inout PVOID volatile *Destination, __in_opt PVOID Exchange, __in_opt PVOID Comparand );
Parameters
- Destination [in, out]
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A pointer to a pointer to the destination value.
- Exchange [in, optional]
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The exchange value.
- Comparand [in, optional]
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The value to compare to Destination.
Return value
The function returns the initial value of the Destination parameter.
Remarks
The function compares the Destination value with the Comparand value. If the Destination value is equal to the Comparand value, the Exchange value is stored in the address specified by Destination. Otherwise, no operation is performed.
On a 64-bit system, the parameters are 64 bits and must be aligned on 64-bit boundaries; otherwise, the function will behave unpredictably. On a 32-bit system, the parameters are 32 bits and must be aligned on 32-bit boundaries.
The interlocked functions provide a simple mechanism for synchronizing access to a variable that is shared by multiple threads. This function is atomic with respect to calls to other interlocked functions.
This function is implemented using a compiler intrinsic where possible. For more information, see the Winbase.h header file and _InterlockedCompareExchangePointer_acq.
For processors that do not support acquire memory access semantics, this function is defined as a call to the InterlockedCompareExchangePointer function. For more information, see Winbase.h.
Requirements
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See also
- Interlocked Variable Access
- InterlockedCompareExchangePointer
- InterlockedCompareExchangePointerRelease
- Synchronization Functions
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Build date: 9/7/2011