atomic_fetch_and, atomic_fetch_and_explicit
Defined in header <stdatomic.h>
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C atomic_fetch_and( volatile A* obj, M arg ); |
(1) | (since C11) |
C atomic_fetch_and_explicit( volatile A* obj, M arg, memory_order order ); |
(2) | (since C11) |
Atomically replaces the value pointed by obj
with the result of bitwise AND between the old value of obj
and arg
, and returns the value obj
held previously. The operation is read-modify-write operation. The first version orders memory accesses according to memory_order_seq_cst, the second version orders memory accesses according to order
.
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. M
is either the non-atomic type corresponding to A
if A
is atomic integer type, or ptrdiff_t if A
is atomic pointer type.
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_fetch_and)(...)), 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 |
arg | - | the value to bitwise AND to the value stored in the atomic object |
order | - | the memory sycnhronization ordering for this operation: all values are permitted |
Return value
The value held previously be the atomic object pointed to by obj
.
References
- C11 standard (ISO/IEC 9899:2011):
- 7.17.7.5 The atomic_fetch and modify generic functions (p: 284-285)
See also
atomic bitwise OR (function) | |
atomic bitwise exclusive OR (function) |