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#ifndef BOOST_SMART_PTR_DETAIL_SP_COUNTED_BASE_VACPP_PPC_HPP_INCLUDED
#define BOOST_SMART_PTR_DETAIL_SP_COUNTED_BASE_VACPP_PPC_HPP_INCLUDED
//
// detail/sp_counted_base_vacpp_ppc.hpp - xlC(vacpp) on POWER
// based on: detail/sp_counted_base_w32.hpp
//
// Copyright (c) 2001, 2002, 2003 Peter Dimov and Multi Media Ltd.
// Copyright 2004-2005 Peter Dimov
// Copyright 2006 Michael van der Westhuizen
// Copyright 2012 IBM Corp.
//
// 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 <boost/detail/sp_typeinfo.hpp>
extern "builtin" void __lwsync(void);
extern "builtin" void __isync(void);
extern "builtin" int __fetch_and_add(volatile int* addr, int val);
extern "builtin" int __compare_and_swap(volatile int*, int*, int);
namespace boost
{
namespace detail
{
inline void atomic_increment( int *pw )
{
// ++*pw;
__lwsync();
__fetch_and_add(pw, 1);
__isync();
}
inline int atomic_decrement( int *pw )
{
// return --*pw;
__lwsync();
int originalValue = __fetch_and_add(pw, -1);
__isync();
return (originalValue - 1);
}
inline int atomic_conditional_increment( int *pw )
{
// if( *pw != 0 ) ++*pw;
// return *pw;
__lwsync();
int v = *const_cast<volatile int*>(pw);
for (;;)
// loop until state is known
{
if (v == 0) return 0;
if (__compare_and_swap(pw, &v, v + 1))
{
__isync(); return (v + 1);
}
}
}
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)
char pad[64] __attribute__((__aligned__(64)));
// pad to prevent false sharing
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;
virtual void * get_untyped_deleter() = 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 *const_cast<volatile int*>(&use_count_);
}
};
} // namespace detail
} // namespace boost
#endif // #ifndef BOOST_SMART_PTR_DETAIL_SP_COUNTED_BASE_VACPP_PPC_HPP_INCLUDED