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#ifndef BOOST_SMART_PTR_DETAIL_SP_COUNTED_BASE_GCC_IA64_HPP_INCLUDED
#define BOOST_SMART_PTR_DETAIL_SP_COUNTED_BASE_GCC_IA64_HPP_INCLUDED
//
// detail/sp_counted_base_gcc_ia64.hpp - g++ on IA64
//
// Copyright (c) 2001, 2002, 2003 Peter Dimov and Multi Media Ltd.
// Copyright 2004-2006 Peter Dimov
// Copyright 2005 Ben Hutchings
//
// 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 <boost/detail/sp_typeinfo.hpp>
namespace boost
{
namespace detail
{
inline void atomic_increment( int * pw )
{
// ++*pw;
int tmp;
// No barrier is required here but fetchadd always has an acquire or
// release barrier associated with it. We choose release as it should be
// cheaper.
__asm__ ("fetchadd4.rel %0=%1,1" :
"=r"(tmp), "=m"(*pw) :
"m"( *pw ));
}
inline int atomic_decrement( int * pw )
{
// return --*pw;
int rv;
__asm__ (" fetchadd4.rel %0=%1,-1 ;; \n"
" cmp.eq p7,p0=1,%0 ;; \n"
"(p7) ld4.acq %0=%1 " :
"=&r"(rv), "=m"(*pw) :
"m"( *pw ) :
"p7");
return rv;
}
inline int atomic_conditional_increment( int * pw )
{
// if( *pw != 0 ) ++*pw;
// return *pw;
int rv, tmp, tmp2;
__asm__ ("0: ld4 %0=%3 ;; \n"
" cmp.eq p7,p0=0,%0 ;; \n"
"(p7) br.cond.spnt 1f \n"
" mov ar.ccv=%0 \n"
" add %1=1,%0 ;; \n"
" cmpxchg4.acq %2=%3,%1,ar.ccv ;; \n"
" cmp.ne p7,p0=%0,%2 ;; \n"
"(p7) br.cond.spnt 0b \n"
" mov %0=%1 ;; \n"
"1:" :
"=&r"(rv), "=&r"(tmp), "=&r"(tmp2), "=m"(*pw) :
"m"( *pw ) :
"ar.ccv", "p7");
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( sp_typeinfo 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_ ) == 0 )
{
dispose();
weak_release();
}
}
void weak_add_ref() // nothrow
{
atomic_increment( &weak_count_ );
}
void weak_release() // nothrow
{
if( atomic_decrement( &weak_count_ ) == 0 )
{
destroy();
}
}
long use_count() const // nothrow
{
return static_cast<int const volatile &>( use_count_ ); // TODO use ld.acq here
}
};
} // namespace detail
} // namespace boost
#endif // #ifndef BOOST_SMART_PTR_DETAIL_SP_COUNTED_BASE_GCC_IA64_HPP_INCLUDED