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#ifndef BOOST_SMART_PTR_DETAIL_SPINLOCK_GCC_ARM_HPP_INCLUDED
#define BOOST_SMART_PTR_DETAIL_SPINLOCK_GCC_ARM_HPP_INCLUDED
//
// Copyright (c) 2008, 2011 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>
#if defined(__ARM_ARCH_7__) || defined(__ARM_ARCH_7A__) || defined(__ARM_ARCH_7R__) || defined(__ARM_ARCH_7M__) || defined(__ARM_ARCH_7EM__) || defined(__ARM_ARCH_7S__)
# define BOOST_SP_ARM_BARRIER "dmb"
# define BOOST_SP_ARM_HAS_LDREX
#elif defined(__ARM_ARCH_6__) || defined(__ARM_ARCH_6J__) || defined(__ARM_ARCH_6K__) || defined(__ARM_ARCH_6Z__) || defined(__ARM_ARCH_6ZK__) || defined(__ARM_ARCH_6T2__)
# define BOOST_SP_ARM_BARRIER "mcr p15, 0, r0, c7, c10, 5"
# define BOOST_SP_ARM_HAS_LDREX
#else
# define BOOST_SP_ARM_BARRIER ""
#endif
namespace boost
{
namespace detail
{
class spinlock
{
public:
int v_;
public:
bool try_lock()
{
int r;
#ifdef BOOST_SP_ARM_HAS_LDREX
__asm__ __volatile__(
"ldrex %0, [%2]; \n"
"cmp %0, %1; \n"
"strexne %0, %1, [%2]; \n"
BOOST_SP_ARM_BARRIER :
"=&r"( r ): // outputs
"r"( 1 ), "r"( &v_ ): // inputs
"memory", "cc" );
#else
__asm__ __volatile__(
"swp %0, %1, [%2];\n"
BOOST_SP_ARM_BARRIER :
"=&r"( r ): // outputs
"r"( 1 ), "r"( &v_ ): // inputs
"memory", "cc" );
#endif
return r == 0;
}
void lock()
{
for( unsigned k = 0; !try_lock(); ++k )
{
boost::detail::yield( k );
}
}
void unlock()
{
__asm__ __volatile__( BOOST_SP_ARM_BARRIER ::: "memory" );
*const_cast< int volatile* >( &v_ ) = 0;
__asm__ __volatile__( BOOST_SP_ARM_BARRIER ::: "memory" );
}
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}
#undef BOOST_SP_ARM_BARRIER
#undef BOOST_SP_ARM_HAS_LDREX
#endif // #ifndef BOOST_SMART_PTR_DETAIL_SPINLOCK_GCC_ARM_HPP_INCLUDED
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