ceph/src/boost/boost/atomic/detail/fp_ops_generic.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) 2018 Andrey Semashev
   7  */
   8 /*!
   9  * \file   atomic/detail/fp_ops_generic.hpp
  10  *
  11  * This header contains generic implementation of the floating point atomic operations.
  12  */
  13
  14 #ifndef BOOST_ATOMIC_DETAIL_FP_OPS_GENERIC_HPP_INCLUDED_
  15 #define BOOST_ATOMIC_DETAIL_FP_OPS_GENERIC_HPP_INCLUDED_
  16
  17 #include <cstddef>
  18 #include <boost/memory_order.hpp>
  19 #include <boost/atomic/detail/config.hpp>
  20 #include <boost/atomic/detail/bitwise_fp_cast.hpp>
  21 #include <boost/atomic/detail/storage_traits.hpp>
  22 #include <boost/atomic/detail/fp_operations_fwd.hpp>
  23 #include <boost/atomic/detail/header.hpp>
  24
  25 #ifdef BOOST_HAS_PRAGMA_ONCE
  26 #pragma once
  27 #endif
  28
  29 namespace boost {
  30 namespace atomics {
  31 namespace detail {
  32
  33 //! Generic implementation of floating point operations
  34 template< typename Base, typename Value, std::size_t Size >
  35 struct fp_operations_generic :
  36     public Base
  37 {
  38     typedef Base base_type;
  39     typedef typename base_type::storage_type storage_type;
  40     typedef Value value_type;
  41
  42     static BOOST_FORCEINLINE value_type fetch_add(storage_type volatile& storage, value_type v, memory_order order) BOOST_NOEXCEPT
  43     {
  44         storage_type old_storage, new_storage;
  45         value_type old_val, new_val;
  46         atomics::detail::non_atomic_load(storage, old_storage);
  47         do
  48         {
  49             old_val = atomics::detail::bitwise_fp_cast< value_type >(old_storage);
  50             new_val = old_val + v;
  51             new_storage = atomics::detail::bitwise_fp_cast< storage_type >(new_val);
  52         }
  53         while (!base_type::compare_exchange_weak(storage, old_storage, new_storage, order, memory_order_relaxed));
  54         return old_val;
  55     }
  56
  57     static BOOST_FORCEINLINE value_type fetch_sub(storage_type volatile& storage, value_type v, memory_order order) BOOST_NOEXCEPT
  58     {
  59         storage_type old_storage, new_storage;
  60         value_type old_val, new_val;
  61         atomics::detail::non_atomic_load(storage, old_storage);
  62         do
  63         {
  64             old_val = atomics::detail::bitwise_fp_cast< value_type >(old_storage);
  65             new_val = old_val - v;
  66             new_storage = atomics::detail::bitwise_fp_cast< storage_type >(new_val);
  67         }
  68         while (!base_type::compare_exchange_weak(storage, old_storage, new_storage, order, memory_order_relaxed));
  69         return old_val;
  70     }
  71 };
  72
  73 // Default fp_operations template definition will be used unless specialized for a specific platform
  74 template< typename Base, typename Value, std::size_t Size >
  75 struct fp_operations< Base, Value, Size, true > :
  76     public fp_operations_generic< Base, Value, Size >
  77 {
  78 };
  79
  80 } // namespace detail
  81 } // namespace atomics
  82 } // namespace boost
  83
  84 #include <boost/atomic/detail/footer.hpp>
  85
  86 #endif // BOOST_ATOMIC_DETAIL_FP_OPS_GENERIC_HPP_INCLUDED_