/*
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* Distributed under the Boost Software License, Version 1.0.
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* (See accompanying file LICENSE_1_0.txt or copy at
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* http://www.boost.org/LICENSE_1_0.txt)
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*
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* Copyright (c) 2011 Helge Bahmann
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* Copyright (c) 2013 Tim Blechmann
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* Copyright (c) 2014, 2020 Andrey Semashev
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*/
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/*!
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* \file atomic/detail/atomic_flag_impl.hpp
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*
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* This header contains implementation of \c atomic_flag.
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*/
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#ifndef BOOST_ATOMIC_DETAIL_ATOMIC_FLAG_IMPL_HPP_INCLUDED_
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#define BOOST_ATOMIC_DETAIL_ATOMIC_FLAG_IMPL_HPP_INCLUDED_
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#include <boost/assert.hpp>
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#include <boost/memory_order.hpp>
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#include <boost/atomic/detail/config.hpp>
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#include <boost/atomic/detail/core_operations.hpp>
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#include <boost/atomic/detail/wait_operations.hpp>
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#include <boost/atomic/detail/aligned_variable.hpp>
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#include <boost/atomic/detail/header.hpp>
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#ifdef BOOST_HAS_PRAGMA_ONCE
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#pragma once
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#endif
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/*
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* IMPLEMENTATION NOTE: All interface functions MUST be declared with BOOST_FORCEINLINE,
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* see comment for convert_memory_order_to_gcc in gcc_atomic_memory_order_utils.hpp.
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*/
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namespace boost {
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namespace atomics {
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namespace detail {
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#if defined(BOOST_ATOMIC_DETAIL_NO_CXX11_CONSTEXPR_UNION_INIT) || defined(BOOST_NO_CXX11_UNIFIED_INITIALIZATION_SYNTAX)
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#define BOOST_ATOMIC_NO_ATOMIC_FLAG_INIT
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#else
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#define BOOST_ATOMIC_FLAG_INIT {}
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#endif
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//! Atomic flag implementation
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template< bool IsInterprocess >
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struct atomic_flag_impl
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{
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// Prefer 4-byte storage as most platforms support waiting/notifying operations without a lock pool for 32-bit integers
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typedef atomics::detail::core_operations< 4u, false, IsInterprocess > core_operations;
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typedef atomics::detail::wait_operations< core_operations > wait_operations;
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typedef typename core_operations::storage_type storage_type;
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static BOOST_CONSTEXPR_OR_CONST bool is_always_lock_free = core_operations::is_always_lock_free;
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static BOOST_CONSTEXPR_OR_CONST bool always_has_native_wait_notify = wait_operations::always_has_native_wait_notify;
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BOOST_ATOMIC_DETAIL_ALIGNED_VAR_TPL(core_operations::storage_alignment, storage_type, m_storage);
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BOOST_FORCEINLINE BOOST_ATOMIC_DETAIL_CONSTEXPR_UNION_INIT atomic_flag_impl() BOOST_NOEXCEPT : m_storage(0u)
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{
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}
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BOOST_FORCEINLINE bool is_lock_free() const volatile BOOST_NOEXCEPT
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{
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return is_always_lock_free;
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}
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BOOST_FORCEINLINE bool has_native_wait_notify() const volatile BOOST_NOEXCEPT
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{
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return wait_operations::has_native_wait_notify(m_storage);
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}
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BOOST_FORCEINLINE bool test(memory_order order = memory_order_seq_cst) const volatile BOOST_NOEXCEPT
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{
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BOOST_ASSERT(order != memory_order_release);
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BOOST_ASSERT(order != memory_order_acq_rel);
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return !!core_operations::load(m_storage, order);
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}
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BOOST_FORCEINLINE bool test_and_set(memory_order order = memory_order_seq_cst) volatile BOOST_NOEXCEPT
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{
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return core_operations::test_and_set(m_storage, order);
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}
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BOOST_FORCEINLINE void clear(memory_order order = memory_order_seq_cst) volatile BOOST_NOEXCEPT
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{
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BOOST_ASSERT(order != memory_order_consume);
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BOOST_ASSERT(order != memory_order_acquire);
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BOOST_ASSERT(order != memory_order_acq_rel);
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core_operations::clear(m_storage, order);
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}
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BOOST_FORCEINLINE bool wait(bool old_val, memory_order order = memory_order_seq_cst) const volatile BOOST_NOEXCEPT
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{
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BOOST_ASSERT(order != memory_order_release);
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BOOST_ASSERT(order != memory_order_acq_rel);
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return !!wait_operations::wait(m_storage, static_cast< storage_type >(old_val), order);
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}
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BOOST_FORCEINLINE void notify_one() volatile BOOST_NOEXCEPT
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{
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wait_operations::notify_one(m_storage);
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}
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BOOST_FORCEINLINE void notify_all() volatile BOOST_NOEXCEPT
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{
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wait_operations::notify_all(m_storage);
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}
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BOOST_DELETED_FUNCTION(atomic_flag_impl(atomic_flag_impl const&))
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BOOST_DELETED_FUNCTION(atomic_flag_impl& operator= (atomic_flag_impl const&))
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};
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#if defined(BOOST_NO_CXX17_INLINE_VARIABLES)
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template< bool IsInterprocess >
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BOOST_CONSTEXPR_OR_CONST bool atomic_flag_impl< IsInterprocess >::is_always_lock_free;
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template< bool IsInterprocess >
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BOOST_CONSTEXPR_OR_CONST bool atomic_flag_impl< IsInterprocess >::always_has_native_wait_notify;
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#endif
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} // namespace detail
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} // namespace atomics
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} // namespace boost
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#include <boost/atomic/detail/footer.hpp>
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#endif // BOOST_ATOMIC_DETAIL_ATOMIC_FLAG_IMPL_HPP_INCLUDED_
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