InterlockedDecrement64 function

Decrements (decreases by one) the value of the specified 64-bit variable as an atomic operation.

To operate on 32-bit values, use the InterlockedDecrement function.

Syntax


LONGLONG __cdecl InterlockedDecrement64(
  _Inout_ LONGLONG volatile *Addend
);

Parameters

Addend [in, out]: A pointer to the variable to be decremented.

Return value

The function returns the resulting decremented value.

Remarks

The variable pointed to by the Addend parameter must be aligned on a 64-bit boundary; otherwise, this function will behave unpredictably on multiprocessor x86 systems and any non-x86 systems. See _aligned_malloc.

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 _InterlockedDecrement64.

This function generates a full memory barrier (or fence) to ensure that memory operations are completed in order.

Itanium-based systems: For performance-critical applications, use InterlockedDecrementAcquire64 or InterlockedDecrementRelease64 instead.

Note This function is supported on Windows RT-based systems.

Note

Requirements

Minimum supported client	Windows Vista [desktop apps \| Windows Store apps]
Minimum supported server	Windows Server 2003 [desktop apps \| Windows Store apps]
Header	WinBase.h (include Windows.h)