_InterlockedExchangePointer Intrinsic Functions
The latest version of this topic can be found at _InterlockedExchangePointer Intrinsic Functions.
Microsoft Specific**
Perform an atomic exchange operation, which copies the address passed in as the second argument to the first and returns the original address of the first.
Syntax
void * _InterlockedExchangePointer(
void * volatile * Target,
void * Value
);
void * _InterlockedExchangePointer_acq(
void * volatile * Target,
void * Value
);
void * _InterlockedExchangePointer_rel(
void * volatile * Target,
void * Value
);
void * _InterlockedExchangePointer_nf(
void * volatile * Target,
void * Value
);
void * _InterlockedExchangePointer_HLEAcquire(
void * volatile * Target,
void * Value
);
void * _InterlockedExchangePointer_HLERelease(
void * volatile * Target,
void * Value
);
Parameters
[in, out] Target
Pointer to the pointer to the value to exchange. The function sets the value to Value and returns its previous value.
[in] Value
Value to be exchanged with the value pointed to by Target.
Return Value
The function returns the initial value pointed to by Target.
Requirements
| Intrinsic | Architecture | Header |
|---|---|---|
_InterlockedExchangePointer |
x86, ARM, x64 | <intrin.h> |
_InterlockedExchangePointer_acq, _InterlockedExchangePointer_rel, _InterlockedExchangePointer_nf |
ARM | <intrin.h> |
_InterlockedExchangePointer_HLEAcquire, _InterlockedExchangePointer_HLERelease |
x64 with HLE support | <immintrin.h> |
On the x86 architecture, _InterlockedExchangePointer is a macro that calls _InterlockedExchange.
Remarks
On a 64-bit system, the parameters are 64 bits and must be aligned on 64-bit boundaries; otherwise, the function fails. On a 32-bit system, the parameters are 32 bits and must be aligned on 32-bit boundaries. For more information, see align.
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 does 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.