#ifndef BOOST_DETAIL_SP_COUNTED_BASE_GCC_M68K_HPP_INCLUDED
#define BOOST_DETAIL_SP_COUNTED_BASE_GCC_M68K_HPP_INCLUDED

//
//  detail/sp_counted_base_gcc_m68k.hpp - g++ on Motorola 68020+
//
//  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
//

#include <typeinfo>

namespace boost
{

namespace detail
{

inline void atomic_increment( long * pw )
{
    // ++*pw;

    __asm__ ("addql 1,*%1" :
	     "=m"(*pw) :
	     "m"(pw) :
	     "cc");
}

inline bool atomic_decrement( long * pw )
{
    // return --*pw != 0;

    bool rv;

    __asm__ (" subql 1,*%1 \n"
	     " sne   %2    \n"
	     " negb  %2    " :
	     "=m"(*pw), "=r"(rv) :
	     "m"(pw) :
	     "cc");

    return rv;
}

inline long atomic_conditional_increment( long * pw )
{
    // if( *pw != 0 ) ++*pw;
    // return *pw;

    long rv, tmp;

    __asm__("0: movel *%3,%0    \n"
	    "   beq   1         \n"
	    "   movel %0,%1     \n"
	    "   addql 1,%0      \n"
	    "   casl  %0,%1,*%3 \n"
	    "   bne   0         \n"
	    "1:" :
	    "=r"(rv), "=r"(tmp), "=m"(*pw) :
	    "r"(pw) :
	    "cc");

    return rv;
}

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( 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_decrement( &use_count_ ) )
        {
            dispose();
            weak_release();
        }
    }

    void weak_add_ref() // nothrow
    {
        atomic_increment( &weak_count_ );
    }

    void weak_release() // nothrow
    {
        if( !atomic_decrement( &weak_count_ ) )
        {
            destroy();
        }
    }

    long use_count() const // nothrow
    {
        return static_cast<long const volatile &>( use_count_ );
    }
};

} // namespace detail

} // namespace boost

#endif  // #ifndef BOOST_DETAIL_SP_COUNTED_BASE_GCC_M68K_HPP_INCLUDED