ceph/src/boost/libs/atomic/include/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
  22 #ifdef BOOST_HAS_PRAGMA_ONCE
  23 #pragma once
  24 #endif
  25
  26 namespace boost {
  27 namespace atomics {
  28 namespace detail {
  29
  30 template< typename Base, std::size_t Size, bool Signed >
  31 struct extending_cas_based_operations :
  32     public Base
  33 {
  34     typedef typename Base::storage_type storage_type;
  35     typedef typename make_storage_type< Size, Signed >::type emulated_storage_type;
  36
  37     static BOOST_FORCEINLINE storage_type fetch_add(storage_type volatile& storage, storage_type v, memory_order order) BOOST_NOEXCEPT
  38     {
  39         storage_type old_val;
  40         atomics::detail::non_atomic_load(storage, old_val);
  41         emulated_storage_type new_val;
  42         do
  43         {
  44             new_val = static_cast< emulated_storage_type >(old_val) + static_cast< emulated_storage_type >(v);
  45         }
  46         while (!Base::compare_exchange_weak(storage, old_val, static_cast< storage_type >(new_val), order, memory_order_relaxed));
  47         return old_val;
  48     }
  49
  50     static BOOST_FORCEINLINE storage_type fetch_sub(storage_type volatile& storage, storage_type v, memory_order order) BOOST_NOEXCEPT
  51     {
  52         storage_type old_val;
  53         atomics::detail::non_atomic_load(storage, old_val);
  54         emulated_storage_type new_val;
  55         do
  56         {
  57             new_val = static_cast< emulated_storage_type >(old_val) - static_cast< emulated_storage_type >(v);
  58         }
  59         while (!Base::compare_exchange_weak(storage, old_val, static_cast< storage_type >(new_val), order, memory_order_relaxed));
  60         return old_val;
  61     }
  62 };
  63
  64 } // namespace detail
  65 } // namespace atomics
  66 } // namespace boost
  67
  68 #endif // BOOST_ATOMIC_DETAIL_OPS_EXTENDING_CAS_BASED_HPP_INCLUDED_