atomic/detail/extra_fp_ops_generic.hpp

0001 /*
0002  * Distributed under the Boost Software License, Version 1.0.
0003  * (See accompanying file LICENSE_1_0.txt or copy at
0004  * http://www.boost.org/LICENSE_1_0.txt)
0005  *
0006  * Copyright (c) 2018 Andrey Semashev
0007  */
0008 /*!
0009  * \file   atomic/detail/extra_fp_ops_generic.hpp
0010  *
0011  * This header contains generic implementation of the extra floating point atomic operations.
0012  */
0013
0014 #ifndef BOOST_ATOMIC_DETAIL_EXTRA_FP_OPS_GENERIC_HPP_INCLUDED_
0015 #define BOOST_ATOMIC_DETAIL_EXTRA_FP_OPS_GENERIC_HPP_INCLUDED_
0016
0017 #include <cstddef>
0018 #include <boost/memory_order.hpp>
0019 #include <boost/atomic/detail/config.hpp>
0020 #include <boost/atomic/detail/bitwise_fp_cast.hpp>
0021 #include <boost/atomic/detail/storage_traits.hpp>
0022 #include <boost/atomic/detail/extra_fp_operations_fwd.hpp>
0023 #include <boost/atomic/detail/type_traits/is_iec559.hpp>
0024 #include <boost/atomic/detail/type_traits/is_integral.hpp>
0025 #include <boost/atomic/detail/header.hpp>
0026
0027 #ifdef BOOST_HAS_PRAGMA_ONCE
0028 #pragma once
0029 #endif
0030
0031 #if defined(BOOST_GCC) && BOOST_GCC >= 60000
0032 #pragma GCC diagnostic push
0033 // ignoring attributes on template argument X - this warning is because we need to pass storage_type as a template argument; no problem in this case
0034 #pragma GCC diagnostic ignored "-Wignored-attributes"
0035 #endif
0036
0037 namespace boost {
0038 namespace atomics {
0039 namespace detail {
0040
0041 //! Negate implementation
0042 template<
0043     typename Base,
0044     typename Value,
0045     std::size_t Size
0046 #if defined(BOOST_ATOMIC_DETAIL_INT_FP_ENDIAN_MATCH)
0047     , bool = atomics::detail::is_iec559< Value >::value && atomics::detail::is_integral< typename Base::storage_type >::value
0048 #endif
0049 >
0050 struct extra_fp_negate_generic :
0051     public Base
0052 {
0053     typedef Base base_type;
0054     typedef typename base_type::storage_type storage_type;
0055     typedef Value value_type;
0056
0057     static BOOST_FORCEINLINE value_type fetch_negate(storage_type volatile& storage, memory_order order) BOOST_NOEXCEPT
0058     {
0059         storage_type old_storage, new_storage;
0060         value_type old_val, new_val;
0061         atomics::detail::non_atomic_load(storage, old_storage);
0062         do
0063         {
0064             old_val = atomics::detail::bitwise_fp_cast< value_type >(old_storage);
0065             new_val = -old_val;
0066             new_storage = atomics::detail::bitwise_fp_cast< storage_type >(new_val);
0067         }
0068         while (!base_type::compare_exchange_weak(storage, old_storage, new_storage, order, memory_order_relaxed));
0069         return old_val;
0070     }
0071
0072     static BOOST_FORCEINLINE value_type negate(storage_type volatile& storage, memory_order order) BOOST_NOEXCEPT
0073     {
0074         storage_type old_storage, new_storage;
0075         value_type old_val, new_val;
0076         atomics::detail::non_atomic_load(storage, old_storage);
0077         do
0078         {
0079             old_val = atomics::detail::bitwise_fp_cast< value_type >(old_storage);
0080             new_val = -old_val;
0081             new_storage = atomics::detail::bitwise_fp_cast< storage_type >(new_val);
0082         }
0083         while (!base_type::compare_exchange_weak(storage, old_storage, new_storage, order, memory_order_relaxed));
0084         return new_val;
0085     }
0086
0087     static BOOST_FORCEINLINE void opaque_negate(storage_type volatile& storage, memory_order order) BOOST_NOEXCEPT
0088     {
0089         fetch_negate(storage, order);
0090     }
0091 };
0092
0093 #if defined(BOOST_ATOMIC_DETAIL_INT_FP_ENDIAN_MATCH)
0094
0095 //! Negate implementation for IEEE 754 / IEC 559 floating point types. We leverage the fact that the sign bit is the most significant bit in the value.
0096 template< typename Base, typename Value, std::size_t Size >
0097 struct extra_fp_negate_generic< Base, Value, Size, true > :
0098     public Base
0099 {
0100     typedef Base base_type;
0101     typedef typename base_type::storage_type storage_type;
0102     typedef Value value_type;
0103
0104     //! The mask with only one sign bit set to 1
0105     static BOOST_CONSTEXPR_OR_CONST storage_type sign_mask = static_cast< storage_type >(1u) << (atomics::detail::value_size_of< value_type >::value * 8u - 1u);
0106
0107     static BOOST_FORCEINLINE value_type fetch_negate(storage_type volatile& storage, memory_order order) BOOST_NOEXCEPT
0108     {
0109         return atomics::detail::bitwise_fp_cast< value_type >(base_type::fetch_xor(storage, sign_mask, order));
0110     }
0111
0112     static BOOST_FORCEINLINE value_type negate(storage_type volatile& storage, memory_order order) BOOST_NOEXCEPT
0113     {
0114         return atomics::detail::bitwise_fp_cast< value_type >(base_type::bitwise_xor(storage, sign_mask, order));
0115     }
0116
0117     static BOOST_FORCEINLINE void opaque_negate(storage_type volatile& storage, memory_order order) BOOST_NOEXCEPT
0118     {
0119         base_type::opaque_xor(storage, sign_mask, order);
0120     }
0121 };
0122
0123 #endif // defined(BOOST_ATOMIC_DETAIL_INT_FP_ENDIAN_MATCH)
0124
0125 //! Generic implementation of floating point operations
0126 template< typename Base, typename Value, std::size_t Size >
0127 struct extra_fp_operations_generic :
0128     public extra_fp_negate_generic< Base, Value, Size >
0129 {
0130     typedef extra_fp_negate_generic< Base, Value, Size > base_type;
0131     typedef typename base_type::storage_type storage_type;
0132     typedef Value value_type;
0133
0134     static BOOST_FORCEINLINE value_type add(storage_type volatile& storage, value_type v, memory_order order) BOOST_NOEXCEPT
0135     {
0136         storage_type old_storage, new_storage;
0137         value_type old_val, new_val;
0138         atomics::detail::non_atomic_load(storage, old_storage);
0139         do
0140         {
0141             old_val = atomics::detail::bitwise_fp_cast< value_type >(old_storage);
0142             new_val = old_val + v;
0143             new_storage = atomics::detail::bitwise_fp_cast< storage_type >(new_val);
0144         }
0145         while (!base_type::compare_exchange_weak(storage, old_storage, new_storage, order, memory_order_relaxed));
0146         return new_val;
0147     }
0148
0149     static BOOST_FORCEINLINE value_type sub(storage_type volatile& storage, value_type v, memory_order order) BOOST_NOEXCEPT
0150     {
0151         storage_type old_storage, new_storage;
0152         value_type old_val, new_val;
0153         atomics::detail::non_atomic_load(storage, old_storage);
0154         do
0155         {
0156             old_val = atomics::detail::bitwise_fp_cast< value_type >(old_storage);
0157             new_val = old_val - v;
0158             new_storage = atomics::detail::bitwise_fp_cast< storage_type >(new_val);
0159         }
0160         while (!base_type::compare_exchange_weak(storage, old_storage, new_storage, order, memory_order_relaxed));
0161         return new_val;
0162     }
0163
0164     static BOOST_FORCEINLINE void opaque_add(storage_type volatile& storage, value_type v, memory_order order) BOOST_NOEXCEPT
0165     {
0166         base_type::fetch_add(storage, v, order);
0167     }
0168
0169     static BOOST_FORCEINLINE void opaque_sub(storage_type volatile& storage, value_type v, memory_order order) BOOST_NOEXCEPT
0170     {
0171         base_type::fetch_sub(storage, v, order);
0172     }
0173 };
0174
0175 // Default extra_fp_operations template definition will be used unless specialized for a specific platform
0176 template< typename Base, typename Value, std::size_t Size >
0177 struct extra_fp_operations< Base, Value, Size, true > :
0178     public extra_fp_operations_generic< Base, Value, Size >
0179 {
0180 };
0181
0182 } // namespace detail
0183 } // namespace atomics
0184 } // namespace boost
0185
0186 #if defined(BOOST_GCC) && BOOST_GCC >= 60000
0187 #pragma GCC diagnostic pop
0188 #endif
0189
0190 #include <boost/atomic/detail/footer.hpp>
0191
0192 #endif // BOOST_ATOMIC_DETAIL_FP_OPS_GENERIC_HPP_INCLUDED_