atomic_exchange(), atomic_exchange

Atomically change the value of an atomic object (C11)

Synopsis:

#include <stdatomic.h>

C atomic_exchange( volatile A *obj,
                   C desired );

C atomic_exchange_explicit( volatile A *obj,
                            C desired,
                            memory_order order );

Arguments:

obj: A pointer to the atomic object (see the atomic_* types) whose value you want to read.
desired: The value for the object. The “C” represents the non-atomic data type that corresponds to the atomic object.
order: (atomic_exchange_explicit() only) The memory_order to use for the operation.

Library:

If the atomic function is lock-free (see atomic_is_lock_free()), no extra library is required.
If the function isn't lock-free, you need to link against libatomic. Use the -l atomic option to qcc to link against this library.

Description:

The atomic_exchange() and atomic_exchange_explicit() functions are generic functions that atomically change the value of the given atomic object. The atomic_exchange() function orders memory access according to memory_order_seq_cst; atomic_exchange_explicit() orders them as specified by order.

Returns:

The value of the object before the operation.

Classification:

C11

Safety:
Cancellation point	No
Interrupt handler	Read the Caveats
Signal handler	Read the Caveats
Thread	Yes

Caveats:

If this function is lock-free (see atomic_is_lock_free()), it's safe to call it from an ISR or signal handler.

atomic_exchange(), atomic_exchange_explicit()