ceph/src/boost/boost/atomic/detail/ops_extending_cas_based.hpp

   1 /*
   2  * Distributed under the Boost Software License, Version 1.0.
   3  * (See accompanying file LICENSE_1_0.txt or copy at
   4  * http://www.boost.org/LICENSE_1_0.txt)
   5  *
   6  * Copyright (c) 2014 Andrey Semashev
   7  */
   8 /*!
   9  * \file   atomic/detail/ops_extending_cas_based.hpp
  10  *
  11  * This header contains a boilerplate of the \c operations template implementation that requires sign/zero extension in arithmetic operations.
  12  */
  13
  14 #ifndef BOOST_ATOMIC_DETAIL_OPS_EXTENDING_CAS_BASED_HPP_INCLUDED_
  15 #define BOOST_ATOMIC_DETAIL_OPS_EXTENDING_CAS_BASED_HPP_INCLUDED_
  16
  17 #include <cstddef>
  18 #include <boost/memory_order.hpp>
  19 #include <boost/atomic/detail/config.hpp>
  20 #include <boost/atomic/detail/storage_type.hpp>
  21 #include <boost/atomic/detail/integral_extend.hpp>
  22
  23 #ifdef BOOST_HAS_PRAGMA_ONCE
  24 #pragma once
  25 #endif
  26
  27 namespace boost {
  28 namespace atomics {
  29 namespace detail {
  30
  31 template< typename Base, std::size_t Size, bool Signed >
  32 struct extending_cas_based_operations :
  33     public Base
  34 {
  35     typedef typename Base::storage_type storage_type;
  36     typedef typename make_storage_type< Size >::type emulated_storage_type;
  37
  38     static BOOST_FORCEINLINE storage_type fetch_add(storage_type volatile& storage, storage_type v, memory_order order) BOOST_NOEXCEPT
  39     {
  40         storage_type old_val;
  41         atomics::detail::non_atomic_load(storage, old_val);
  42         storage_type new_val;
  43         do
  44         {
  45             new_val = atomics::detail::integral_extend< Signed, storage_type >(static_cast< emulated_storage_type >(old_val + v));
  46         }
  47         while (!Base::compare_exchange_weak(storage, old_val, new_val, order, memory_order_relaxed));
  48         return old_val;
  49     }
  50
  51     static BOOST_FORCEINLINE storage_type fetch_sub(storage_type volatile& storage, storage_type v, memory_order order) BOOST_NOEXCEPT
  52     {
  53         storage_type old_val;
  54         atomics::detail::non_atomic_load(storage, old_val);
  55         storage_type new_val;
  56         do
  57         {
  58             new_val = atomics::detail::integral_extend< Signed, storage_type >(static_cast< emulated_storage_type >(old_val - v));
  59         }
  60         while (!Base::compare_exchange_weak(storage, old_val, new_val, order, memory_order_relaxed));
  61         return old_val;
  62     }
  63 };
  64
  65 } // namespace detail
  66 } // namespace atomics
  67 } // namespace boost
  68
  69 #endif // BOOST_ATOMIC_DETAIL_OPS_EXTENDING_CAS_BASED_HPP_INCLUDED_