smart_ptr/include/boost/detail/atomic_count_sync.hpp

#ifndef BOOST_DETAIL_ATOMIC_COUNT_SYNC_HPP_INCLUDED
#define BOOST_DETAIL_ATOMIC_COUNT_SYNC_HPP_INCLUDED

//
//  boost/detail/atomic_count_sync.hpp
//
//  atomic_count for g++ 4.1+
//
//  http://gcc.gnu.org/onlinedocs/gcc-4.1.1/gcc/Atomic-Builtins.html
//
//  Copyright 2007 Peter Dimov
//
//  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)
//

namespace boost
{

namespace detail
{

class atomic_count
{
public:

    explicit atomic_count( long v ) : value_( v ) {}

    void operator++()
    {
        __sync_add_and_fetch( &value_, 1 );
    }

    long operator--()
    {
        return __sync_add_and_fetch( &value_, -1 );
    }

    operator long() const
    {
        return __sync_fetch_and_add( &value_, 0 );
    }

private:

    atomic_count(atomic_count const &);
    atomic_count & operator=(atomic_count const &);

    mutable long value_;
};

} // namespace detail

} // namespace boost

#endif // #ifndef BOOST_DETAIL_ATOMIC_COUNT_SYNC_HPP_INCLUDED