text: /*
   * Distributed under the Boost Software License, Version 1.0.
   * (See accompanying file LICENSE_1_0.txt or copy at
   * http://www.boost.org/LICENSE_1_0.txt)
   *
   * Copyright (c) 2009 Helge Bahmann
   * Copyright (c) 2012 Tim Blechmann
   * Copyright (c) 2014 Andrey Semashev
   */
  /*!
   * \file   atomic/detail/ops_windows.hpp
   *
   * This header contains implementation of the \c operations template.
   *
   * This implementation is the most basic version for Windows. It should
   * work for any non-MSVC-like compilers as long as there are Interlocked WinAPI
   * functions available. This version is also used for WinCE.
   *
   * Notably, this implementation is not as efficient as other
   * versions based on compiler intrinsics.
   */
  
  #ifndef BOOST_ATOMIC_DETAIL_OPS_WINDOWS_HPP_INCLUDED_
  #define BOOST_ATOMIC_DETAIL_OPS_WINDOWS_HPP_INCLUDED_
  
  #include <cstddef>
  #include <boost/memory_order.hpp>
  #include <boost/atomic/detail/config.hpp>
  #include <boost/atomic/detail/interlocked.hpp>
  #include <boost/atomic/detail/storage_type.hpp>
  #include <boost/atomic/detail/operations_fwd.hpp>
  #include <boost/atomic/detail/type_traits/make_signed.hpp>
  #include <boost/atomic/capabilities.hpp>
  #include <boost/atomic/detail/ops_msvc_common.hpp>
  #include <boost/atomic/detail/ops_extending_cas_based.hpp>
  
  #ifdef BOOST_HAS_PRAGMA_ONCE
  #pragma once
  #endif
  
  namespace boost {
  namespace atomics {
  namespace detail {
  
  struct windows_operations_base
  {
      static BOOST_CONSTEXPR_OR_CONST bool full_cas_based = false;
      static BOOST_CONSTEXPR_OR_CONST bool is_always_lock_free = true;
  
      static BOOST_FORCEINLINE void hardware_full_fence() BOOST_NOEXCEPT
      {
          long tmp;
          BOOST_ATOMIC_INTERLOCKED_EXCHANGE(&tmp, 0);
      }
  
      static BOOST_FORCEINLINE void fence_before(memory_order) BOOST_NOEXCEPT
      {
          BOOST_ATOMIC_DETAIL_COMPILER_BARRIER();
      }
  
      static BOOST_FORCEINLINE void fence_after(memory_order) BOOST_NOEXCEPT
      {
          BOOST_ATOMIC_DETAIL_COMPILER_BARRIER();
      }
  };
  
  template< std::size_t Size, bool Signed, typename Derived >
  struct windows_operations :
      public windows_operations_base
  {
      typedef typename make_storage_type< Size >::type storage_type;
      typedef typename make_storage_type< Size >::aligned aligned_storage_type;
  
      static BOOST_CONSTEXPR_OR_CONST std::size_t storage_size = Size;
      static BOOST_CONSTEXPR_OR_CONST bool is_signed = Signed;
  
      static BOOST_FORCEINLINE void store(storage_type volatile& storage, storage_type v, memory_order order) BOOST_NOEXCEPT
      {
          Derived::exchange(storage, v, order);
      }
  
      static BOOST_FORCEINLINE storage_type load(storage_type const volatile& storage, memory_order order) BOOST_NOEXCEPT
      {
          return Derived::fetch_add(const_cast< storage_type volatile& >(storage), (storage_type)0, order);
      }
  
      static BOOST_FORCEINLINE storage_type fetch_sub(storage_type volatile& storage, storage_type v, memory_order order) BOOST_NOEXCEPT
      {
          typedef typename boost::atomics::detail::make_signed< storage_type >::type signed_storage_type;
          return Derived::fetch_add(storage, static_cast< storage_type >(-static_cast< signed_storage_type >(v)), order);
      }
  
      static BOOST_FORCEINLINE bool compare_exchange_weak(
          storage_type volatile& storage, storage_type& expected, storage_type desired, memory_order success_order, memory_order failure_order) BOOST_NOEXCEPT
      {
          return Derived::compare_exchange_strong(storage, expected, desired, success_order, failure_order);
      }
  
      static BOOST_FORCEINLINE bool test_and_set(storage_type volatile& storage, memory_order order) BOOST_NOEXCEPT
      {
          return !!Derived::exchange(storage, (storage_type)1, order);
      }
  
      static BOOST_FORCEINLINE void clear(storage_type volatile& storage, memory_order order) BOOST_NOEXCEPT
      {
          store(storage, (storage_type)0, order);
      }
  };
  
  template< bool Signed >
  struct operations< 4u, Signed > :
      public windows_operations< 4u, Signed, operations< 4u, Signed > >
  {
      typedef windows_operations< 4u, Signed, operations< 4u, Signed > > base_type;
      typedef typename base_type::storage_type storage_type;
  
      static BOOST_FORCEINLINE storage_type fetch_add(storage_type volatile& storage, storage_type v, memory_order order) BOOST_NOEXCEPT
      {
          base_type::fence_before(order);
          v = static_cast< storage_type >(BOOST_ATOMIC_INTERLOCKED_EXCHANGE_ADD(&storage, v));
          base_type::fence_after(order);
          return v;
      }
  
      static BOOST_FORCEINLINE storage_type exchange(storage_type volatile& storage, storage_type v, memory_order order) BOOST_NOEXCEPT
      {
          base_type::fence_before(order);
          v = static_cast< storage_type >(BOOST_ATOMIC_INTERLOCKED_EXCHANGE(&storage, v));
          base_type::fence_after(order);
          return v;
      }
  
      static BOOST_FORCEINLINE bool compare_exchange_strong(
          storage_type volatile& storage, storage_type& expected, storage_type desired, memory_order success_order, memory_order failure_order) BOOST_NOEXCEPT
      {
          storage_type previous = expected;
          base_type::fence_before(success_order);
          storage_type old_val = static_cast< storage_type >(BOOST_ATOMIC_INTERLOCKED_COMPARE_EXCHANGE(&storage, desired, previous));
          expected = old_val;
          // The success and failure fences are the same anyway
          base_type::fence_after(success_order);
          return (previous == old_val);
      }
  
      static BOOST_FORCEINLINE storage_type fetch_and(storage_type volatile& storage, storage_type v, memory_order order) BOOST_NOEXCEPT
      {
  #if defined(BOOST_ATOMIC_INTERLOCKED_AND)
          base_type::fence_before(order);
          v = static_cast< storage_type >(BOOST_ATOMIC_INTERLOCKED_AND(&storage, v));
          base_type::fence_after(order);
          return v;
  #else
          storage_type res = storage;
          while (!compare_exchange_strong(storage, res, res & v, order, memory_order_relaxed)) {}
          return res;
  #endif
      }
  
      static BOOST_FORCEINLINE storage_type fetch_or(storage_type volatile& storage, storage_type v, memory_order order) BOOST_NOEXCEPT
      {
  #if defined(BOOST_ATOMIC_INTERLOCKED_OR)
          base_type::fence_before(order);
          v = static_cast< storage_type >(BOOST_ATOMIC_INTERLOCKED_OR(&storage, v));
          base_type::fence_after(order);
          return v;
  #else
          storage_type res = storage;
          while (!compare_exchange_strong(storage, res, res | v, order, memory_order_relaxed)) {}
          return res;
  #endif
      }
  
      static BOOST_FORCEINLINE storage_type fetch_xor(storage_type volatile& storage, storage_type v, memory_order order) BOOST_NOEXCEPT
      {
  #if defined(BOOST_ATOMIC_INTERLOCKED_XOR)
          base_type::fence_before(order);
          v = static_cast< storage_type >(BOOST_ATOMIC_INTERLOCKED_XOR(&storage, v));
          base_type::fence_after(order);
          return v;
  #else
          storage_type res = storage;
          while (!compare_exchange_strong(storage, res, res ^ v, order, memory_order_relaxed)) {}
          return res;
  #endif
      }
  };
  
  template< bool Signed >
  struct operations< 1u, Signed > :
      public extending_cas_based_operations< operations< 4u, Signed >, 1u, Signed >
  {
  };
  
  template< bool Signed >
  struct operations< 2u, Signed > :
      public extending_cas_based_operations< operations< 4u, Signed >, 2u, Signed >
  {
  };
  
  BOOST_FORCEINLINE void thread_fence(memory_order order) BOOST_NOEXCEPT
  {
      BOOST_ATOMIC_DETAIL_COMPILER_BARRIER();
      if (order == memory_order_seq_cst)
          windows_operations_base::hardware_full_fence();
      BOOST_ATOMIC_DETAIL_COMPILER_BARRIER();
  }
  
  BOOST_FORCEINLINE void signal_fence(memory_order order) BOOST_NOEXCEPT
  {
      if (order != memory_order_relaxed)
          BOOST_ATOMIC_DETAIL_COMPILER_BARRIER();
  }
  
  } // namespace detail
  } // namespace atomics
  } // namespace boost
  
  #endif // BOOST_ATOMIC_DETAIL_OPS_WINDOWS_HPP_INCLUDED_
  