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A portable version of stdatomic.h extracted from the FreeBSD libc, for Clang 3.1+ and GCC 4.7+.
/*
* An implementation of C11 stdatomic.h directly borrowed from FreeBSD
* (original copyright follows), with minor modifications for
* portability to other systems. Works for recent Clang (that
* implement the feature c_atomic) and GCC 4.7+; includes
* compatibility for GCC below 4.7 but I wouldn't recommend it.
*
* Caveats and limitations:
* - Only the ``_Atomic parentheses'' notation is implemented, while
* the ``_Atomic space'' one is not.
* - _Atomic types must be typedef'ed, or programs using them will
* not type check correctly (incompatible anonymous structure
* types).
* - Non-scalar _Atomic types would require runtime support for
* runtime locking, which, as far as I know, is not currently
* available on any system.
*/
/*-
* Copyright (c) 2011 Ed Schouten <ed@FreeBSD.org>
* David Chisnall <theraven@FreeBSD.org>
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*
* $FreeBSD: src/include/stdatomic.h,v 1.10.2.2 2012/05/30 19:21:54 theraven Exp $
*/
#ifndef _STDATOMIC_H_
#define _STDATOMIC_H_
#include <stddef.h>
#include <stdint.h>
#if !defined(__has_feature)
#define __has_feature(x) 0
#endif
#if !defined(__has_builtin)
#define __has_builtin(x) 0
#endif
#if !defined(__GNUC_PREREQ__)
#if defined(__GNUC__) && defined(__GNUC_MINOR__)
#define __GNUC_PREREQ__(maj, min) \
((__GNUC__ << 16) + __GNUC_MINOR__ >= ((maj) << 16) + (min))
#else
#define __GNUC_PREREQ__(maj, min) 0
#endif
#endif
#if !defined(__CLANG_ATOMICS) && !defined(__GNUC_ATOMICS)
#if __has_feature(c_atomic)
#define __CLANG_ATOMICS
#elif __GNUC_PREREQ__(4, 7)
#define __GNUC_ATOMICS
#elif !defined(__GNUC__)
#error "stdatomic.h does not support your compiler"
#endif
#endif
#if !defined(__CLANG_ATOMICS)
#define _Atomic(T) struct { volatile __typeof__(T) __val; }
#endif
/*
* 7.17.2 Initialization.
*/
#if defined(__CLANG_ATOMICS)
#define ATOMIC_VAR_INIT(value) (value)
#define atomic_init(obj, value) __c11_atomic_init(obj, value)
#else
#define ATOMIC_VAR_INIT(value) { .__val = (value) }
#define atomic_init(obj, value) do { \
(obj)->__val = (value); \
} while (0)
#endif
/*
* Clang and recent GCC both provide predefined macros for the memory
* orderings. If we are using a compiler that doesn't define them, use the
* clang values - these will be ignored in the fallback path.
*/
#ifndef __ATOMIC_RELAXED
#define __ATOMIC_RELAXED 0
#endif
#ifndef __ATOMIC_CONSUME
#define __ATOMIC_CONSUME 1
#endif
#ifndef __ATOMIC_ACQUIRE
#define __ATOMIC_ACQUIRE 2
#endif
#ifndef __ATOMIC_RELEASE
#define __ATOMIC_RELEASE 3
#endif
#ifndef __ATOMIC_ACQ_REL
#define __ATOMIC_ACQ_REL 4
#endif
#ifndef __ATOMIC_SEQ_CST
#define __ATOMIC_SEQ_CST 5
#endif
/*
* 7.17.3 Order and consistency.
*
* The memory_order_* constants that denote the barrier behaviour of the
* atomic operations.
*/
enum memory_order {
memory_order_relaxed = __ATOMIC_RELAXED,
memory_order_consume = __ATOMIC_CONSUME,
memory_order_acquire = __ATOMIC_ACQUIRE,
memory_order_release = __ATOMIC_RELEASE,
memory_order_acq_rel = __ATOMIC_ACQ_REL,
memory_order_seq_cst = __ATOMIC_SEQ_CST
};
typedef enum memory_order memory_order;
/*
* 7.17.4 Fences.
*/
#ifdef __CLANG_ATOMICS
#define atomic_thread_fence(order) __c11_atomic_thread_fence(order)
#define atomic_signal_fence(order) __c11_atomic_signal_fence(order)
#elif defined(__GNUC_ATOMICS)
#define atomic_thread_fence(order) __atomic_thread_fence(order)
#define atomic_signal_fence(order) __atomic_signal_fence(order)
#else
#define atomic_thread_fence(order) __sync_synchronize()
#define atomic_signal_fence(order) __asm volatile ("" : : : "memory")
#endif
/*
* 7.17.5 Lock-free property.
*/
#if defined(__CLANG_ATOMICS)
#define atomic_is_lock_free(obj) \
__c11_atomic_is_lock_free(sizeof(obj))
#elif defined(__GNUC_ATOMICS)
#define atomic_is_lock_free(obj) \
__atomic_is_lock_free(sizeof((obj)->__val))
#else
#define atomic_is_lock_free(obj) \
(sizeof((obj)->__val) <= sizeof(void *))
#endif
/*
* 7.17.6 Atomic integer types.
*/
typedef _Atomic(_Bool) atomic_bool;
typedef _Atomic(char) atomic_char;
typedef _Atomic(signed char) atomic_schar;
typedef _Atomic(unsigned char) atomic_uchar;
typedef _Atomic(short) atomic_short;
typedef _Atomic(unsigned short) atomic_ushort;
typedef _Atomic(int) atomic_int;
typedef _Atomic(unsigned int) atomic_uint;
typedef _Atomic(long) atomic_long;
typedef _Atomic(unsigned long) atomic_ulong;
typedef _Atomic(long long) atomic_llong;
typedef _Atomic(unsigned long long) atomic_ullong;
#if 0
typedef _Atomic(char16_t) atomic_char16_t;
typedef _Atomic(char32_t) atomic_char32_t;
#endif
typedef _Atomic(wchar_t) atomic_wchar_t;
typedef _Atomic(int_least8_t) atomic_int_least8_t;
typedef _Atomic(uint_least8_t) atomic_uint_least8_t;
typedef _Atomic(int_least16_t) atomic_int_least16_t;
typedef _Atomic(uint_least16_t) atomic_uint_least16_t;
typedef _Atomic(int_least32_t) atomic_int_least32_t;
typedef _Atomic(uint_least32_t) atomic_uint_least32_t;
typedef _Atomic(int_least64_t) atomic_int_least64_t;
typedef _Atomic(uint_least64_t) atomic_uint_least64_t;
typedef _Atomic(int_fast8_t) atomic_int_fast8_t;
typedef _Atomic(uint_fast8_t) atomic_uint_fast8_t;
typedef _Atomic(int_fast16_t) atomic_int_fast16_t;
typedef _Atomic(uint_fast16_t) atomic_uint_fast16_t;
typedef _Atomic(int_fast32_t) atomic_int_fast32_t;
typedef _Atomic(uint_fast32_t) atomic_uint_fast32_t;
typedef _Atomic(int_fast64_t) atomic_int_fast64_t;
typedef _Atomic(uint_fast64_t) atomic_uint_fast64_t;
typedef _Atomic(intptr_t) atomic_intptr_t;
typedef _Atomic(uintptr_t) atomic_uintptr_t;
typedef _Atomic(size_t) atomic_size_t;
typedef _Atomic(ptrdiff_t) atomic_ptrdiff_t;
typedef _Atomic(intmax_t) atomic_intmax_t;
typedef _Atomic(uintmax_t) atomic_uintmax_t;
/*
* 7.17.7 Operations on atomic types.
*/
/*
* Compiler-specific operations.
*/
#if defined(__CLANG_ATOMICS)
#define atomic_compare_exchange_strong_explicit(object, expected, \
desired, success, failure) \
__c11_atomic_compare_exchange_strong(object, expected, desired, \
success, failure)
#define atomic_compare_exchange_weak_explicit(object, expected, \
desired, success, failure) \
__c11_atomic_compare_exchange_weak(object, expected, desired, \
success, failure)
#define atomic_exchange_explicit(object, desired, order) \
__c11_atomic_exchange(object, desired, order)
#define atomic_fetch_add_explicit(object, operand, order) \
__c11_atomic_fetch_add(object, operand, order)
#define atomic_fetch_and_explicit(object, operand, order) \
__c11_atomic_fetch_and(object, operand, order)
#define atomic_fetch_or_explicit(object, operand, order) \
__c11_atomic_fetch_or(object, operand, order)
#define atomic_fetch_sub_explicit(object, operand, order) \
__c11_atomic_fetch_sub(object, operand, order)
#define atomic_fetch_xor_explicit(object, operand, order) \
__c11_atomic_fetch_xor(object, operand, order)
#define atomic_load_explicit(object, order) \
__c11_atomic_load(object, order)
#define atomic_store_explicit(object, desired, order) \
__c11_atomic_store(object, desired, order)
#elif defined(__GNUC_ATOMICS)
#define atomic_compare_exchange_strong_explicit(object, expected, \
desired, success, failure) \
__atomic_compare_exchange_n(&(object)->__val, expected, \
desired, 0, success, failure)
#define atomic_compare_exchange_weak_explicit(object, expected, \
desired, success, failure) \
__atomic_compare_exchange_n(&(object)->__val, expected, \
desired, 1, success, failure)
#define atomic_exchange_explicit(object, desired, order) \
__atomic_exchange_n(&(object)->__val, desired, order)
#define atomic_fetch_add_explicit(object, operand, order) \
__atomic_fetch_add(&(object)->__val, operand, order)
#define atomic_fetch_and_explicit(object, operand, order) \
__atomic_fetch_and(&(object)->__val, operand, order)
#define atomic_fetch_or_explicit(object, operand, order) \
__atomic_fetch_or(&(object)->__val, operand, order)
#define atomic_fetch_sub_explicit(object, operand, order) \
__atomic_fetch_sub(&(object)->__val, operand, order)
#define atomic_fetch_xor_explicit(object, operand, order) \
__atomic_fetch_xor(&(object)->__val, operand, order)
#define atomic_load_explicit(object, order) \
__atomic_load_n(&(object)->__val, order)
#define atomic_store_explicit(object, desired, order) \
__atomic_store_n(&(object)->__val, desired, order)
#else
#define atomic_compare_exchange_strong_explicit(object, expected, \
desired, success, failure) ({ \
__typeof__((object)->__val) __v; \
_Bool __r; \
__v = __sync_val_compare_and_swap(&(object)->__val, \
*(expected), desired); \
__r = *(expected) == __v; \
*(expected) = __v; \
__r; \
})
#define atomic_compare_exchange_weak_explicit(object, expected, \
desired, success, failure) \
atomic_compare_exchange_strong_explicit(object, expected, \
desired, success, failure)
#if __has_builtin(__sync_swap)
/* Clang provides a full-barrier atomic exchange - use it if available. */
#define atomic_exchange_explicit(object, desired, order) \
__sync_swap(&(object)->__val, desired)
#else
/*
* __sync_lock_test_and_set() is only an acquire barrier in theory (although in
* practice it is usually a full barrier) so we need an explicit barrier after
* it.
*/
#define atomic_exchange_explicit(object, desired, order) ({ \
__typeof__((object)->__val) __v; \
__v = __sync_lock_test_and_set(&(object)->__val, desired); \
__sync_synchronize(); \
__v; \
})
#endif
#define atomic_fetch_add_explicit(object, operand, order) \
__sync_fetch_and_add(&(object)->__val, operand)
#define atomic_fetch_and_explicit(object, operand, order) \
__sync_fetch_and_and(&(object)->__val, operand)
#define atomic_fetch_or_explicit(object, operand, order) \
__sync_fetch_and_or(&(object)->__val, operand)
#define atomic_fetch_sub_explicit(object, operand, order) \
__sync_fetch_and_sub(&(object)->__val, operand)
#define atomic_fetch_xor_explicit(object, operand, order) \
__sync_fetch_and_xor(&(object)->__val, operand)
#define atomic_load_explicit(object, order) \
__sync_fetch_and_add(&(object)->__val, 0)
#define atomic_store_explicit(object, desired, order) do { \
__sync_synchronize(); \
(object)->__val = (desired); \
__sync_synchronize(); \
} while (0)
#endif
/*
* Convenience functions.
*/
#define atomic_compare_exchange_strong(object, expected, desired) \
atomic_compare_exchange_strong_explicit(object, expected, \
desired, memory_order_seq_cst, memory_order_seq_cst)
#define atomic_compare_exchange_weak(object, expected, desired) \
atomic_compare_exchange_weak_explicit(object, expected, \
desired, memory_order_seq_cst, memory_order_seq_cst)
#define atomic_exchange(object, desired) \
atomic_exchange_explicit(object, desired, memory_order_seq_cst)
#define atomic_fetch_add(object, operand) \
atomic_fetch_add_explicit(object, operand, memory_order_seq_cst)
#define atomic_fetch_and(object, operand) \
atomic_fetch_and_explicit(object, operand, memory_order_seq_cst)
#define atomic_fetch_or(object, operand) \
atomic_fetch_or_explicit(object, operand, memory_order_seq_cst)
#define atomic_fetch_sub(object, operand) \
atomic_fetch_sub_explicit(object, operand, memory_order_seq_cst)
#define atomic_fetch_xor(object, operand) \
atomic_fetch_xor_explicit(object, operand, memory_order_seq_cst)
#define atomic_load(object) \
atomic_load_explicit(object, memory_order_seq_cst)
#define atomic_store(object, desired) \
atomic_store_explicit(object, desired, memory_order_seq_cst)
/*
* 7.17.8 Atomic flag type and operations.
*/
typedef atomic_bool atomic_flag;
#define ATOMIC_FLAG_INIT ATOMIC_VAR_INIT(0)
#define atomic_flag_clear_explicit(object, order) \
atomic_store_explicit(object, 0, order)
#define atomic_flag_test_and_set_explicit(object, order) \
atomic_compare_exchange_strong_explicit(object, 0, 1, order, order)
#define atomic_flag_clear(object) \
atomic_flag_clear_explicit(object, memory_order_seq_cst)
#define atomic_flag_test_and_set(object) \
atomic_flag_test_and_set_explicit(object, memory_order_seq_cst)
#endif /* !_STDATOMIC_H_ */
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