#ifndef BOOST_DETAIL_SP_COUNTED_BASE_GCC_X86_HPP_INCLUDED

#define BOOST_DETAIL_SP_COUNTED_BASE_GCC_X86_HPP_INCLUDED

// MS compatible compilers support #pragma once

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

# pragma once

#endif

//

//  detail/sp_counted_base_gcc_x86.hpp - g++ on 486+ or AMD64

//

//  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 <typeinfo>

namespace boost

{

namespace detail

{

inline int atomic_exchange_and_add( int * pw, int dv )

{

    // int r = *pw;

    // *pw += dv;

    // return r;

    int r;

    __asm__ __volatile__

    (

        "lock\n\t"

        "xadd %1, %0":

        "=m"( *pw ), "=r"( r ): // outputs (%0, %1)

        "m"( *pw ), "1"( dv ): // inputs (%2, %3 == %1)

        "memory", "cc" // clobbers

    );

    return r;

}

inline void atomic_increment( int * pw )

{

    //atomic_exchange_and_add( pw, 1 );

    __asm__

    (

        "lock\n\t"

        "incl %0":

        "=m"( *pw ): // output (%0)

        "m"( *pw ): // input (%1)

        "cc" // clobbers

    );

}

inline int atomic_conditional_increment( int * pw )

{

    // int rv = *pw;

    // if( rv != 0 ) ++*pw;

    // return rv;

    int rv, tmp;

    __asm__

    (

        "movl %0, %%eax\n\t"

        "0:\n\t"

        "test %%eax, %%eax\n\t"

        "je 1f\n\t"

        "movl %%eax, %2\n\t"

        "incl %2\n\t"

        "lock\n\t"

        "cmpxchgl %2, %0\n\t"

        "jne 0b\n\t"

        "1:":

        "=m"( *pw ), "=&a"( rv ), "=&r"( tmp ): // outputs (%0, %1, %2)

        "m"( *pw ): // input (%3)

        "cc" // clobbers

    );

    return rv;

}

class sp_counted_base

{

private:

    sp_counted_base( sp_counted_base const & );

    sp_counted_base & operator= ( sp_counted_base const & );

    int use_count_;        // #shared

    int 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( std::type_info const & ti ) = 0;

    void add_ref_copy()

    {

        atomic_increment( &use_count_ );

    }

    bool add_ref_lock() // true on success

    {

        return atomic_conditional_increment( &use_count_ ) != 0;

    }

    void release() // nothrow

    {

        if( atomic_exchange_and_add( &use_count_, -1 ) == 1 )

        {

            dispose();

            weak_release();

        }

    }

    void weak_add_ref() // nothrow

    {

        atomic_increment( &weak_count_ );

    }

    void weak_release() // nothrow

    {

        if( atomic_exchange_and_add( &weak_count_, -1 ) == 1 )

        {

            destroy();

        }

    }

    long use_count() const // nothrow

    {

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

    }

};

} // namespace detail

} // namespace boost

#endif  // #ifndef BOOST_DETAIL_SP_COUNTED_BASE_GCC_X86_HPP_INCLUDED