atomic_init - cppreference.com (original) (raw)
| | | | | ------------------------------------------------- | | ----------- | | void atomic_init( volatile A* obj, C desired ); | | (since C11) |
Initializes the default-constructed atomic object obj with the value desired. The function is not atomic: concurrent access from another thread, even through an atomic operation, is a data race.
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_init)(...)), or a program defines an external identifier with the name of a generic function, the behavior is undefined.
[edit] Parameters
| obj | - | pointer to an atomic object to initialize |
|---|---|---|
| desired | - | the value to initialize atomic object with |
[edit] Return value
(none)
[edit] Notes
atomic_init is the only way to initialize dynamically-allocated atomic objects. For example:
_Atomic int *p = malloc(sizeof(_Atomic int)); atomic_init(p, 42);
[edit] References
C23 standard (ISO/IEC 9899:2024):
7.17.2.2 The atomic_init generic function (p: TBD)
C17 standard (ISO/IEC 9899:2018):
7.17.2.2 The atomic_init generic function (p: 201)
C11 standard (ISO/IEC 9899:2011):
7.17.2.2 The atomic_init generic function (p: 274-275)