atomic_store, atomic_store_explicit

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Defined in header <stdatomic.h>
void atomic_store ( volatile A * obj , C desired ) ;
(1) (since C11)
void atomic_store_explicit ( volatile A * obj, C desired, memory_order order ) ;
(2) (since C11)

Atomically replaces the value of the atomic variable pointed to by obj with desired . The operation is atomic write operation.

The first version orders memory accesses according to memory_order_seq_cst , the second version orders memory accesses according to order . order must be one of memory_order_relaxed , memory_order_release or memory_order_seq_cst . Otherwise the behavior is undefined.

This is a generic function defined for all atomic object types A . The argument is pointer to a volatile atomic type to accept addresses of both non-volatile and volatile (e.g. memory-mapped I/O) atomic objects, and volatile semantic is preserved when applying this operation to volatile atomic objects. C is the non-atomic type corresponding to A .

It is unspecified whether the name of a generic function is a macro or an identifier declared with external linkage. If a macro definition is suppressed in order to access an actual function (e.g. parenthesized like ( atomic_store ) ( ... ) ), or a program defines an external identifier with the name of a generic function, the behavior is undefined.

Parameters

obj - pointer to the atomic object to modify
order - the memory synchronization ordering for this operation

Return value

(none)

References

  • C17 standard (ISO/IEC 9899:2018):
  • 7.17.7.1 The atomic_store generic functions (p: 206)
  • C11 standard (ISO/IEC 9899:2011):
  • 7.17.7.1 The atomic_store generic functions (p: 282)

See also

reads a value from an atomic object
(function)
C++ documentation for atomic_store , atomic_store_explicit