#ifndef BOOST_SMART_PTR_DETAIL_SP_COUNTED_BASE_W32_HPP_INCLUDED

#define BOOST_SMART_PTR_DETAIL_SP_COUNTED_BASE_W32_HPP_INCLUDED

// MS compatible compilers support #pragma once

#if defined(_MSC_VER) && (_MSC_VER >= 1020)

# pragma once

#endif

//

//  detail/sp_counted_base_w32.hpp

//

//  Copyright (c) 2001, 2002, 2003 Peter Dimov and Multi Media Ltd.

//  Copyright 2004-2005 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)

//

//

//  Lock-free algorithm by Alexander Terekhov

//

//  Thanks to Ben Hitchings for the #weak + (#shared != 0)

//  formulation

//

#include <boost/detail/interlocked.hpp>

#include <boost/detail/workaround.hpp>

#include <boost/detail/sp_typeinfo.hpp>

namespace boost

{

namespace detail

{

class sp_counted_base

{

private:

    sp_counted_base( sp_counted_base const & );

    sp_counted_base & operator= ( sp_counted_base const & );

    long use_count_;        // #shared

    long weak_count_;       // #weak + (#shared != 0)

public:

    sp_counted_base(): use_count_( 1 ), weak_count_( 1 )

    {

    }

    virtual ~sp_counted_base() // nothrow

    {

    }

    // dispose() is called when use_count_ drops to zero, to release

    // the resources managed by *this.

    virtual void dispose() = 0; // nothrow

    // destroy() is called when weak_count_ drops to zero.

    virtual void destroy() // nothrow

    {

        delete this;

    }

    virtual void * get_deleter( sp_typeinfo const & ti ) = 0;

    void add_ref_copy()

    {

        BOOST_INTERLOCKED_INCREMENT( &use_count_ );

    }

    bool add_ref_lock() // true on success

    {

        for( ;; )

        {

            long tmp = static_cast< long const volatile& >( use_count_ );

            if( tmp == 0 ) return false;

#if defined( BOOST_MSVC ) && BOOST_WORKAROUND( BOOST_MSVC, == 1200 )

            // work around a code generation bug

            long tmp2 = tmp + 1;

            if( BOOST_INTERLOCKED_COMPARE_EXCHANGE( &use_count_, tmp2, tmp ) == tmp2 - 1 ) return true;

#else

            if( BOOST_INTERLOCKED_COMPARE_EXCHANGE( &use_count_, tmp + 1, tmp ) == tmp ) return true;

#endif

        }

    }

    void release() // nothrow

    {

        if( BOOST_INTERLOCKED_DECREMENT( &use_count_ ) == 0 )

        {

            dispose();

            weak_release();

        }

    }

    void weak_add_ref() // nothrow

    {

        BOOST_INTERLOCKED_INCREMENT( &weak_count_ );

    }

    void weak_release() // nothrow

    {

        if( BOOST_INTERLOCKED_DECREMENT( &weak_count_ ) == 0 )

        {

            destroy();

        }

    }

    long use_count() const // nothrow

    {

        return static_cast<long const volatile &>( use_count_ );

    }

};

} // namespace detail

} // namespace boost

#endif  // #ifndef BOOST_SMART_PTR_DETAIL_SP_COUNTED_BASE_W32_HPP_INCLUDED