#ifndef BOOST_SMART_PTR_DETAIL_SPINLOCK_GCC_ARM_HPP_INCLUDED

#define BOOST_SMART_PTR_DETAIL_SPINLOCK_GCC_ARM_HPP_INCLUDED

//

//  Copyright (c) 2008 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)

//

#include <boost/smart_ptr/detail/yield_k.hpp>

namespace boost

{

namespace detail

{

class spinlock

{

public:

    int v_;

public:

    bool try_lock()

    {

        int r;

        __asm__ __volatile__(

            "swp %0, %1, [%2]":

            "=&r"( r ): // outputs

            "r"( 1 ), "r"( &v_ ): // inputs

            "memory", "cc" );

        return r == 0;

    }

    void lock()

    {

        for( unsigned k = 0; !try_lock(); ++k )

        {

            boost::detail::yield( k );

        }

    }

    void unlock()

    {

        __asm__ __volatile__( "" ::: "memory" );

        *const_cast< int volatile* >( &v_ ) = 0;

    }

public:

    class scoped_lock

    {

    private:

        spinlock & sp_;

        scoped_lock( scoped_lock const & );

        scoped_lock & operator=( scoped_lock const & );

    public:

        explicit scoped_lock( spinlock & sp ): sp_( sp )

        {

            sp.lock();

        }

        ~scoped_lock()

        {

            sp_.unlock();

        }

    };

};

} // namespace detail

} // namespace boost

#define BOOST_DETAIL_SPINLOCK_INIT {0}

#endif // #ifndef BOOST_SMART_PTR_DETAIL_SPINLOCK_GCC_ARM_HPP_INCLUDED