/*
* Copyright (c) 2019 Apple Inc. All rights reserved.
*
* @APPLE_OSREFERENCE_LICENSE_HEADER_START@
*
* This file contains Original Code and/or Modifications of Original Code
* as defined in and that are subject to the Apple Public Source License
* Version 2.0 (the 'License'). You may not use this file except in
* compliance with the License. The rights granted to you under the License
* may not be used to create, or enable the creation or redistribution of,
* unlawful or unlicensed copies of an Apple operating system, or to
* circumvent, violate, or enable the circumvention or violation of, any
* terms of an Apple operating system software license agreement.
*
* Please obtain a copy of the License at
* http://www.opensource.apple.com/apsl/ and read it before using this file.
*
* The Original Code and all software distributed under the License are
* distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
* EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
* INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
* Please see the License for the specific language governing rights and
* limitations under the License.
*
* @APPLE_OSREFERENCE_LICENSE_HEADER_END@
*/
#ifndef __OS_ATOMIC_H__
#define __OS_ATOMIC_H__
/*!
* @file <os/atomic.h>
*
* @brief
* Small header that helps write code that works with both C11 and C++11,
* or pre-C11 type declarations.
*
* @discussion
* The macros below allow to write code like this, that can be put in a header
* and will work with both C11 and C++11:
*
* <code>
* struct old_type {
* int atomic_field;
* } old_variable;
*
* os_atomic_std(atomic_fetch_add_explicit)(
* os_cast_to_atomic_pointer(&old_variable), 1,
* os_atomic_std(memory_order_relaxed));
* </code>
*/
#include <os/base.h>
#ifndef OS_ATOMIC_USES_CXX
#ifdef KERNEL
#define OS_ATOMIC_USES_CXX 0
#elif defined(__cplusplus) && __cplusplus >= 201103L
#define OS_ATOMIC_USES_CXX 1
#else
#define OS_ATOMIC_USES_CXX 0
#endif
#endif
#if OS_ATOMIC_USES_CXX
#include <atomic>
#define OS_ATOMIC_STD std::
#define os_atomic_std(op) std::op
#define os_atomic(type) std::atomic<type> volatile
#define os_cast_to_atomic_pointer(p) os::cast_to_atomic_pointer(p)
#define os_atomic_basetypeof(p) decltype(os_cast_to_atomic_pointer(p)->load())
#define os_cast_to_nonatomic_pointer(p) os::cast_to_nonatomic_pointer(p)
#else /* !OS_ATOMIC_USES_CXX */
#include <stdatomic.h>
#define OS_ATOMIC_STD
#define os_atomic_std(op) op
#define os_atomic(type) type volatile _Atomic
#define os_cast_to_atomic_pointer(p) (__typeof__(*(p)) volatile _Atomic *)(uintptr_t)(p)
#define os_atomic_basetypeof(p) __typeof__(atomic_load(os_cast_to_atomic_pointer(p)))
#define os_cast_to_nonatomic_pointer(p) (os_atomic_basetypeof(p) *)(uintptr_t)(p)
#endif /* !OS_ATOMIC_USES_CXX */
/*!
* @group Internal implementation details
*
* @discussion The functions below are not intended to be used directly.
*/
#if OS_ATOMIC_USES_CXX
#include <type_traits>
namespace os {
template <class T> using remove_volatile_t = typename std::remove_volatile<T>::type;
template <class T>
inline volatile std::atomic<remove_volatile_t<T> > *
cast_to_atomic_pointer(T *v)
{
return reinterpret_cast<volatile std::atomic<remove_volatile_t<T> > *>(v);
}
template <class T>
inline volatile std::atomic<remove_volatile_t<T> > *
cast_to_atomic_pointer(std::atomic<T> *v)
{
return reinterpret_cast<volatile std::atomic<remove_volatile_t<T> > *>(v);
}
template <class T>
inline volatile std::atomic<remove_volatile_t<T> > *
cast_to_atomic_pointer(volatile std::atomic<T> *v)
{
return reinterpret_cast<volatile std::atomic<remove_volatile_t<T> > *>(v);
}
template <class T>
inline remove_volatile_t<T> *
cast_to_nonatomic_pointer(T *v)
{
return const_cast<remove_volatile_t<T> *>(v);
}
template <class T>
inline remove_volatile_t<T> *
cast_to_nonatomic_pointer(std::atomic<T> *v)
{
return reinterpret_cast<remove_volatile_t<T> *>(v);
}
template <class T>
inline remove_volatile_t<T> *
cast_to_nonatomic_pointer(volatile std::atomic<T> *v)
{
auto _v = const_cast<std::atomic<T> *>(v);
return reinterpret_cast<remove_volatile_t<T> *>(_v);
}
};
#endif /* OS_ATOMIC_USES_CXX */
#endif /* __OS_ATOMIC_H__ */