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/*
* Copyright (C) Igor Sysoev
* Copyright (C) NGINX, Inc.
*/
#ifndef _NXT_ATOMIC_H_INCLUDED_
#define _NXT_ATOMIC_H_INCLUDED_
/*
* nxt_atomic_try_lock() must set an acquire barrier on lock.
* nxt_atomic_xchg() must set an acquire barrier.
* nxt_atomic_release() must set a release barrier.
*/
#if (NXT_HAVE_GCC_ATOMIC) /* GCC 4.1 builtin atomic operations */
typedef intptr_t nxt_atomic_int_t;
typedef uintptr_t nxt_atomic_uint_t;
typedef volatile nxt_atomic_uint_t nxt_atomic_t;
/*
* __sync_bool_compare_and_swap() is a full barrier.
* __sync_lock_test_and_set() is an acquire barrier.
* __sync_lock_release() is a release barrier.
*/
#define nxt_atomic_cmp_set(lock, cmp, set) \
__sync_bool_compare_and_swap(lock, cmp, set)
#define nxt_atomic_xchg(lock, set) \
__sync_lock_test_and_set(lock, set)
#define nxt_atomic_fetch_add(value, add) \
__sync_fetch_and_add(value, add)
#define nxt_atomic_try_lock(lock) \
nxt_atomic_cmp_set(lock, 0, 1)
#define nxt_atomic_release(lock) \
__sync_lock_release(lock)
#define nxt_atomic_or_fetch(ptr, val) \
__sync_or_and_fetch(ptr, val)
#define nxt_atomic_and_fetch(ptr, val) \
__sync_and_and_fetch(ptr, val)
#if (__i386__ || __i386 || __amd64__ || __amd64)
#define nxt_cpu_pause() \
__asm__ ("pause")
#elif (__aarch64__ || __arm64__)
#define nxt_cpu_pause() \
__asm__ ("isb")
#else
#define nxt_cpu_pause()
#endif
/* elif (NXT_HAVE_MACOSX_ATOMIC) */
/*
* The atomic(3) interface has been introduced in MacOS 10.4 (Tiger) and
* extended in 10.5 (Leopard). However its support is omitted because:
*
* 1) the interface is still incomplete:
* *) there are OSAtomicAdd32Barrier() and OSAtomicAdd64Barrier()
* but no OSAtomicAddLongBarrier();
* *) there is no interface for XCHG operation.
*
* 2) the interface is tuned for non-SMP systems due to omission of the
* LOCK prefix on single CPU system but nowadays MacOSX systems are at
* least dual core. Thus these indirect calls just add overhead as
* compared with inlined atomic operations which are supported by GCC
* and Clang in modern MacOSX systems.
*/
#endif /* NXT_HAVE_GCC_ATOMIC */
#endif /* _NXT_ATOMIC_H_INCLUDED_ */
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