W3cubDocs

/C++

std::atomic_fetch_xor, std::atomic_fetch_xor_explicit

Defined in header `<atomic>`
	(1)	(since C++11)
template< class T > T atomic_fetch_xor( std::atomic<T>* obj, typename std::atomic<T>::value_type arg ) noexcept;
template< class T > T atomic_fetch_xor( volatile std::atomic<T>* obj, typename std::atomic<T>::value_type arg ) noexcept;
	(2)	(since C++11)
template< class T > T atomic_fetch_xor_explicit( std::atomic<T>* obj, typename std::atomic<T>::value_type arg, std::memory_order order) noexcept;
template< class T > T atomic_fetch_xor_explicit( volatile std::atomic<T>* obj, typename std::atomic<T>::value_type arg, std::memory_order order) noexcept;

Atomically replaces the value pointed by obj with the result of bitwise XOR between the old value of obj and arg. Returns the value obj held previously.

The operation is performed as if the following is executed:

1) obj->fetch_xor(arg)

2) obj->fetch_xor(arg, order)

If std::atomic<T> has no fetch_xor member (this member is only provided for integral types), the program is ill-formed.

Parameters

obj	-	pointer to the atomic object to modify
arg	-	the value to bitwise XOR to the value stored in the atomic object
order	-	the memory synchronization ordering for this operation: all values are permitted.

Return value

The value immediately preceding the effects of this function in the modification order of *obj.

Possible implementation

template< class T >
T atomic_fetch_xor( std::atomic<T>* obj, typename std::atomic<T>::value_type arg )
{
    return obj->fetch_xor(arg);
}

Example

Defect reports

The following behavior-changing defect reports were applied retroactively to previously published C++ standards.

DR	Applied to	Behavior as published	Correct behavior
P0558R1	C++11	exact type match required because `T` is deduced from multiple arguments	`T` is deduced from the `atomic` argument only

fetch_xor	atomically performs bitwise XOR between the argument and the value of the atomic object and obtains the value held previously (public member function of `std::atomic<T>`)
atomic_fetch_oratomic_fetch_or_explicit (C++11)(C++11)	replaces the atomic object with the result of bitwise OR with a non-atomic argument and obtains the previous value of the atomic (function template)
atomic_fetch_andatomic_fetch_and_explicit (C++11)(C++11)	replaces the atomic object with the result of bitwise AND with a non-atomic argument and obtains the previous value of the atomic (function template)