`_InterlockedIncrement` intrinsic functions

Article
2021-08-03

Provide compiler intrinsic support for the Win32 Windows SDK InterlockedIncrement function. The _InterlockedIncrement intrinsic functions are Microsoft-specific.

Syntax

long _InterlockedIncrement(
   long volatile * lpAddend
);
long _InterlockedIncrement_acq(
   long volatile * lpAddend
);
long _InterlockedIncrement_rel(
   long volatile * lpAddend
);
long _InterlockedIncrement_nf(
   long volatile * lpAddend
);
short _InterlockedIncrement16(
   short volatile * lpAddend
);
short _InterlockedIncrement16_acq(
   short volatile * lpAddend
);
short _InterlockedIncrement16_rel(
   short volatile * lpAddend
);
short _InterlockedIncrement16_nf (
   short volatile * lpAddend
);
__int64 _InterlockedIncrement64(
   __int64 volatile * lpAddend
);
__int64 _InterlockedIncrement64_acq(
   __int64 volatile * lpAddend
);
__int64 _InterlockedIncrement64_rel(
   __int64 volatile * lpAddend
);
__int64 _InterlockedIncrement64_nf(
   __int64 volatile * lpAddend
);

Parameters

lpAddend
[in, out] Pointer to the variable to be incremented.

Return value

The return value is the resulting incremented value.

Requirements

Intrinsic	Architecture	Header
`_InterlockedIncrement`, `_InterlockedIncrement16`	x86, ARM, x64, ARM64	<intrin.h>
`_InterlockedIncrement64`	ARM, x64, ARM64	<intrin.h>
`_InterlockedIncrement_acq`, `_InterlockedIncrement_rel`, `_InterlockedIncrement_nf`, `_InterlockedIncrement16_acq`, `_InterlockedIncrement16_rel`, `_InterlockedIncrement16_nf`, `_InterlockedIncrement64_acq`, `_InterlockedIncrement64_rel`, `_InterlockedIncrement64_nf`	ARM, ARM64	<intrin.h>

Remarks

There are several variations on _InterlockedIncrement that vary based on the data types they involve and whether processor-specific acquire or release semantics is used.

While the _InterlockedIncrement function operates on 32-bit integer values, _InterlockedIncrement16 operates on 16-bit integer values and _InterlockedIncrement64 operates on 64-bit integer values.

On ARM platforms, use the intrinsics with _acq and _rel suffixes if you need acquire and release semantics, such as at the beginning and end of a critical section. The intrinsic with an _nf ("no fence") suffix doesn't act as a memory barrier.

The variable pointed to by the lpAddend parameter must be aligned on a 32-bit boundary; otherwise, this function fails on multiprocessor x86 systems and any non-x86 systems. For more information, see align.

The Win32 function is declared in Wdm.h or Ntddk.h.

These routines are only available as intrinsics.

Example

For a sample of how to use _InterlockedIncrement, see _InterlockedDecrement.

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_InterlockedIncrement intrinsic functions