interlockedcompareexchangepointer-intrinsic-functions.md

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Learn more about: _InterlockedCompareExchangePointer intrinsic functions	_InterlockedCompareExchangePointer intrinsic functions	09/02/2019	_InterlockedCompareExchangePointer_HLERelease _InterlockedCompareExchangePointer_rel _InterlockedCompareExchangePointer_acq_cpp _InterlockedCompareExchangePointer _InterlockedCompareExchangePointer_cpp _InterlockedCompareExchangePointer_np _InterlockedCompareExchangePointer_rel_cpp _InterlockedCompareExchangePointer_HLEAcquire _InterlockedCompareExchangePointer_acq _InterlockedCompareExchangePointer_nf	InterlockedCompareExchangePointer_acq intrinsic _InterlockedCompareExchangePointer_rel intrinsic _InterlockedCompareExchangePointer_acq intrinsic InterlockedCompareExchangePointer_rel intrinsic InterlockedCompareExchangePointer intrinsic _InterlockedCompareExchangePointer_HLERelease intrinsic _InterlockedCompareExchangePointer_HLEAcquire intrinsic _InterlockedCompareExchangePointer intrinsic _InterlockedCompareExchangePointer_nf intrinsic _InterlockedCompareExchangePointer_np intrinsic	97fde59d-2bf9-42aa-a0fe-a5b6befdd44b

_InterlockedCompareExchangePointer intrinsic functions

Microsoft Specific

Performs an atomic operation that stores the Exchange address in the Destination address if the Comparand and the Destination address are equal.

Syntax

void * _InterlockedCompareExchangePointer (
   void * volatile * Destination,
   void * Exchange,
   void * Comparand
);
void * _InterlockedCompareExchangePointer_acq (
   void * volatile * Destination,
   void * Exchange,
   void * Comparand
);
void * _InterlockedCompareExchangePointer_HLEAcquire (
   void * volatile * Destination,
   void * Exchange,
   void * Comparand
);
void * _InterlockedCompareExchangePointer_HLERelease (
   void * volatile * Destination,
   void * Exchange,
   void * Comparand
);
void * _InterlockedCompareExchangePointer_nf (
   void * volatile * Destination,
   void * Exchange,
   void * Comparand
);
void * _InterlockedCompareExchangePointer_np (
   void * volatile * Destination,
   void * Exchange,
   void * Comparand
);
void * _InterlockedCompareExchangePointer_rel (
   void * volatile * Destination,
   void * Exchange,
   void * Comparand
);

Parameters

Destination
[in, out] Pointer to a pointer to the destination value. The sign is ignored.

Exchange
[in] Exchange pointer. The sign is ignored.

Comparand
[in] Pointer to compare to destination. The sign is ignored.

Return value

The return value is the initial value of the destination.

Requirements

Intrinsic	Architecture	Header
_InterlockedCompareExchangePointer	x86, ARM, x64, ARM64	<intrin.h>
_InterlockedCompareExchangePointer_acq, _InterlockedCompareExchangePointer_nf, _InterlockedCompareExchangePointer_rel	ARM, ARM64	<iiintrin.h>
_InterlockedCompareExchangePointer_HLEAcquire, _InterlockedCompareExchangePointer_HLERelease	x86, x64	<immintrin.h>

Remarks

_InterlockedCompareExchangePointer performs an atomic comparison of the Destination address with the Comparand address. If the Destination address is equal to the Comparand address, the Exchange address is stored in the address specified by Destination. Otherwise, no operation is performed.

_InterlockedCompareExchangePointer provides compiler intrinsic support for the Win32 Windows SDK InterlockedCompareExchangePointer function.

For an example of how to use _InterlockedCompareExchangePointer, see _InterlockedDecrement.

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. ARM intrinsics with an _nf ("no fence") suffix don't act as a memory barrier.

The intrinsics with an _np ("no prefetch") suffix prevent a possible prefetch operation from being inserted by the compiler.

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 don't support HLE, the hint is ignored.

These routines are only available as intrinsics.

END Microsoft Specific

See also

Compiler intrinsics
Keywords