Chris@16: #ifndef BOOST_MEMORY_ORDER_HPP_INCLUDED
Chris@16: #define BOOST_MEMORY_ORDER_HPP_INCLUDED
Chris@16: 
Chris@16: // MS compatible compilers support #pragma once
Chris@16: 
Chris@16: #if defined(_MSC_VER) && (_MSC_VER >= 1020)
Chris@16: # pragma once
Chris@16: #endif
Chris@16: 
Chris@16: //  boost/memory_order.hpp
Chris@16: //
Chris@16: //  Defines enum boost::memory_order per the C++0x working draft
Chris@16: //
Chris@16: //  Copyright (c) 2008, 2009 Peter Dimov
Chris@16: //
Chris@16: //  Distributed under the Boost Software License, Version 1.0.
Chris@16: //  See accompanying file LICENSE_1_0.txt or copy at
Chris@16: //  http://www.boost.org/LICENSE_1_0.txt)
Chris@16: 
Chris@16: 
Chris@16: namespace boost
Chris@16: {
Chris@16: 
Chris@16: //
Chris@16: // Enum values are chosen so that code that needs to insert
Chris@16: // a trailing fence for acquire semantics can use a single
Chris@16: // test such as:
Chris@16: //
Chris@16: // if( mo & memory_order_acquire ) { ...fence... }
Chris@16: //
Chris@16: // For leading fences one can use:
Chris@16: //
Chris@16: // if( mo & memory_order_release ) { ...fence... }
Chris@16: //
Chris@16: // Architectures such as Alpha that need a fence on consume
Chris@16: // can use:
Chris@16: //
Chris@16: // if( mo & ( memory_order_acquire | memory_order_consume ) ) { ...fence... }
Chris@16: //
Chris@101: // The values are also in the order of increasing "strength"
Chris@101: // of the fences so that success/failure orders can be checked
Chris@101: // efficiently in compare_exchange methods.
Chris@101: //
Chris@16: 
Chris@16: enum memory_order
Chris@16: {
Chris@16:     memory_order_relaxed = 0,
Chris@101:     memory_order_consume = 1,
Chris@101:     memory_order_acquire = 2,
Chris@101:     memory_order_release = 4,
Chris@101:     memory_order_acq_rel = 6, // acquire | release
Chris@101:     memory_order_seq_cst = 14 // acq_rel | 8
Chris@16: };
Chris@16: 
Chris@16: } // namespace boost
Chris@16: 
Chris@16: #endif // #ifndef BOOST_MEMORY_ORDER_HPP_INCLUDED