stdatomic.h

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/*-
 * 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.
 *
 * $FreeBSD$
 */
 
#ifndef _STDATOMIC_H_
#define _STDATOMIC_H_ 1
 
#include <stdbool.h>
#include <stddef.h>
#include <stdint.h>
 
#ifndef __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
#define __GNUC_PREREQ__(ma, mi) __GNUC_PREREQ(ma, mi)
 
#ifndef __has_feature
#define __has_feature(x) 0
#endif
 
#if __has_feature(cxx_atomic)
#define __CLANG_ATOMICS
#elif __GNUC_PREREQ__(4, 7)
#define __GNUC_ATOMICS
#elif !defined(__GNUC__)
#error "stdatomic.h does not support your compiler"
#endif
 
#if !defined(__CLANG_ATOMICS)
#define _Atomic(T) \
    struct \
    { \
        volatile 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
};
 
/*
 * 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)
 
/*
 * Atomic integers for C11
 */
 
typedef _Atomic(uint64_t) atomic_uint64_t;
typedef _Atomic(uint32_t) atomic_uint32_t;
typedef _Atomic(uint16_t) atomic_uint16_t;
typedef _Atomic(uint8_t) atomic_uint8_t;
 
typedef _Atomic(int64_t) atomic_int64_t;
typedef _Atomic(int32_t) atomic_int32_t;
typedef _Atomic(int16_t) atomic_int16_t;
typedef _Atomic(int8_t) atomic_int8_t;
 
#endif /* !_STDATOMIC_H_ */