ATOMIC_CAS(3) | Library Functions Manual | ATOMIC_CAS(3) |
uint32_t
atomic_cas_32(volatile uint32_t *ptr, uint32_t expected, uint32_t new);
unsigned int
atomic_cas_uint(volatile unsigned int *ptr, unsigned int expected, unsigned int new);
unsigned long
atomic_cas_ulong(volatile unsigned long *ptr, unsigned long expected, unsigned long new);
void *
atomic_cas_ptr(volatile void *ptr, void *expected, void *new);
uint64_t
atomic_cas_64(volatile uint64_t *ptr, uint64_t expected, uint64_t new);
uint32_t
atomic_cas_32_ni(volatile uint32_t *ptr, uint32_t expected, uint32_t new);
unsigned int
atomic_cas_uint_ni(volatile unsigned int *ptr, unsigned int expected, unsigned int new);
unsigned long
atomic_cas_ulong_ni(volatile unsigned long *ptr, unsigned long expected, unsigned long new);
void *
atomic_cas_ptr_ni(volatile void *ptr, void *expected, void *new);
uint64_t
atomic_cas_64_ni(volatile uint64_t *ptr, uint64_t expected, uint64_t new);
The non-interlocked variants, *_ni(), guarantee atomicity within the same CPU with respect to interrupts and preemption. They are not atomic with respect to different CPUs. These can be used to avoid interprocessor synchronization overhead in some cases; for example, they are suitable for synchronized operations on a variable shared by a thread and an interrupt that are bound to the same CPU.
The 64-bit variants of these functions are available only on platforms that can support atomic 64-bit memory access. Applications can check for the availability of 64-bit atomic memory operations by testing if the pre-processor macro __HAVE_ATOMIC64_OPS is defined.
February 2, 2014 | NetBSD 7.2 |