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