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_InterlockedExchange Intrinsic Functions

Microsoft Specific

Generates an atomic instruction to set a specified value.

long _InterlockedExchange(
   long volatile * Target,
   long Value
);
long _InterlockedExchange_acq(
   long volatile * Target,
   long Value
);
long _InterlockedExchange_HLEAcquire(
   long volatile * Target,
   long Value
);
long _InterlockedExchange_HLERelease(
   long volatile * Target,
   long Value
);
long _InterlockedExchange_nf(
   long volatile * Target,
   long Value
);
long _InterlockedExchange_rel(
   long volatile * Target,
   long Value
);
char _InterlockedExchange8(
   char volatile * Target,
   char Value
);
char _InterlockedExchange8_acq(
   char volatile * Target,
   char Value
);
char _InterlockedExchange8_nf(
   char volatile * Target,
   char Value
);
char _InterlockedExchange8_rel(
   char volatile * Target,
   char Value
);
short _InterlockedExchange16(
   short volatile * Target,
   short Value
);
short _InterlockedExchange16_acq(
   short volatile * Target,
   short Value
);
short _InterlockedExchange16_nf(
   short volatile * Target,
   short Value
);
short _InterlockedExchange16_rel(
   short volatile * Target,
   short Value
);
__int64 _InterlockedExchange64(
   __int64 volatile * Target,
   __int64 Value
);
__int64 _InterlockedExchange64_acq(
   __int64 volatile * Target,
   __int64 Value
);
__int64 _InterlockedExchange64_HLEAcquire(
   __int64 volatile * Target,
   __int64 Value
);
__int64 _InterlockedExchange64_HLERelease(
   __int64 volatile * Target,
   __int64 Value
);
__int64 _InterlockedExchange64_nf(
   __int64 volatile * Target,
   __int64 Value
);
__int64 _InterlockedExchange64_rel(
   __int64 volatile * Target,
   __int64 Value
);

[in, out] Target

Pointer to the value to be exchanged. The function sets this variable to Value and returns its prior value.

[in] Value

Value to be exchanged with the value pointed to by Target.

Returns the initial value pointed to by Target.

Intrinsic

Architecture

Header

_InterlockedExchange, _InterlockedExchange8, _InterlockedExchange16, _InterlockedExchange64

x86, ARM, x64

<intrin.h>

_InterlockedExchange_acq, _InterlockedExchange_nf, _InterlockedExchange_rel, _InterlockedExchange8_acq, _InterlockedExchange8_nf, _InterlockedExchange8_rel, _InterlockedExchange16_acq, _InterlockedExchange16_nf, _InterlockedExchange16_rel, _InterlockedExchange64_acq, _InterlockedExchange64_nf, _InterlockedExchange64_rel,

ARM

<intrin.h>

_InterlockedExchange_HLEAcquire, _InterlockedExchange_HLERelease, _InterlockedExchange64_HLEAcquire, _InterlockedExchange64_HLERelease

x86, x64

<immintrin.h>

_InterlockedExchange provides compiler intrinsic support for the Win32 Windows SDK InterlockedExchange function.

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

While the _InterlockedExchange function operates on 32-bit integer values, _InterlockedExchange8 operates on 8-bit integer values, _InterlockedExchange16 operates on 16-bit integer values, and _InterlockedExchange64 operates on 64-bit integer values.

On ARM platforms, use the intrinsics with _acq and _rel suffixes for acquire and release semantics, such as at the beginning and end of a critical section. The intrinsics with an _nf ("no fence") suffix do not act as a memory barrier.

On Intel platforms that support Hardware Lock Elision (HLE) instructions, the intrinsics with _HLEAcquire and _HLERelease suffixes include a hint to the processor that can accelerate performance by eliminating a lock write step in hardware. If these intrinsics are called on platforms that do not support HLE, the hint is ignored.

These routines are only available as intrinsics.

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

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