1//
2// detail/atomic_count.hpp
3// ~~~~~~~~~~~~~~~~~~~~~~~
4//
5// Copyright (c) 2003-2015 Christopher M. Kohlhoff (chris at kohlhoff dot com)
6//
7// Distributed under the Boost Software License, Version 1.0. (See accompanying
8// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
9//
10
11#ifndef BOOST_ASIO_DETAIL_ATOMIC_COUNT_HPP
12#define BOOST_ASIO_DETAIL_ATOMIC_COUNT_HPP
13
14#if defined(_MSC_VER) && (_MSC_VER >= 1200)
15# pragma once
16#endif // defined(_MSC_VER) && (_MSC_VER >= 1200)
17
18#include <boost/asio/detail/config.hpp>
19
20#if !defined(BOOST_ASIO_HAS_THREADS)
21// Nothing to include.
22#elif defined(BOOST_ASIO_HAS_STD_ATOMIC)
23# include <atomic>
24#else // defined(BOOST_ASIO_HAS_STD_ATOMIC)
25# include <boost/detail/atomic_count.hpp>
26#endif // defined(BOOST_ASIO_HAS_STD_ATOMIC)
27
28namespace boost {
29namespace asio {
30namespace detail {
31
32#if !defined(BOOST_ASIO_HAS_THREADS)
33typedef long atomic_count;
34inline void increment(atomic_count& a, long b) { a += b; }
35#elif defined(BOOST_ASIO_HAS_STD_ATOMIC)
36typedef std::atomic<long> atomic_count;
37inline void increment(atomic_count& a, long b) { a += b; }
38#else // defined(BOOST_ASIO_HAS_STD_ATOMIC)
39typedef boost::detail::atomic_count atomic_count;
40inline void increment(atomic_count& a, long b) { while (b > 0) ++a, --b; }
41#endif // defined(BOOST_ASIO_HAS_STD_ATOMIC)
42
43} // namespace detail
44} // namespace asio
45} // namespace boost
46
47#endif // BOOST_ASIO_DETAIL_ATOMIC_COUNT_HPP
48

source code of boost/boost/asio/detail/atomic_count.hpp