58 lines
1.5 KiB
C++
58 lines
1.5 KiB
C++
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#ifndef BOOST_MEMORY_ORDER_HPP_INCLUDED
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#define BOOST_MEMORY_ORDER_HPP_INCLUDED
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// MS compatible compilers support #pragma once
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#if defined(_MSC_VER) && (_MSC_VER >= 1020)
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# pragma once
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#endif
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// boost/memory_order.hpp
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//
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// Defines enum boost::memory_order per the C++0x working draft
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//
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// Copyright (c) 2008, 2009 Peter Dimov
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//
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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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namespace boost
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{
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//
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// Enum values are chosen so that code that needs to insert
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// a trailing fence for acquire semantics can use a single
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// test such as:
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//
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// if( mo & memory_order_acquire ) { ...fence... }
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//
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// For leading fences one can use:
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//
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// if( mo & memory_order_release ) { ...fence... }
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//
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// Architectures such as Alpha that need a fence on consume
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// can use:
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//
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// if( mo & ( memory_order_acquire | memory_order_consume ) ) { ...fence... }
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//
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// The values are also in the order of increasing "strength"
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// of the fences so that success/failure orders can be checked
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// efficiently in compare_exchange methods.
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//
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enum memory_order
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{
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memory_order_relaxed = 0,
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memory_order_consume = 1,
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memory_order_acquire = 2,
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memory_order_release = 4,
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memory_order_acq_rel = 6, // acquire | release
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memory_order_seq_cst = 14 // acq_rel | 8
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};
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} // namespace boost
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#endif // #ifndef BOOST_MEMORY_ORDER_HPP_INCLUDED
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