#ifndef BOOST_SMART_PTR_DETAIL_SP_COUNTED_BASE_CW_X86_HPP_INCLUDED | |
#define BOOST_SMART_PTR_DETAIL_SP_COUNTED_BASE_CW_X86_HPP_INCLUDED | |
// MS compatible compilers support #pragma once | |
#if defined(_MSC_VER) && (_MSC_VER >= 1020) | |
# pragma once | |
#endif | |
// | |
// detail/sp_counted_base_cw_x86.hpp - CodeWarrion on 486+ | |
// | |
// Copyright (c) 2001, 2002, 2003 Peter Dimov and Multi Media Ltd. | |
// Copyright 2004-2005 Peter Dimov | |
// Copyright 2005 Rene Rivera | |
// | |
// 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> | |
namespace boost | |
{ | |
namespace detail | |
{ | |
inline int atomic_exchange_and_add( int * pw, int dv ) | |
{ | |
// int r = *pw; | |
// *pw += dv; | |
// return r; | |
asm | |
{ | |
mov esi, [pw] | |
mov eax, dv | |
lock xadd dword ptr [esi], eax | |
} | |
} | |
inline void atomic_increment( int * pw ) | |
{ | |
//atomic_exchange_and_add( pw, 1 ); | |
asm | |
{ | |
mov esi, [pw] | |
lock inc dword ptr [esi] | |
} | |
} | |
inline int atomic_conditional_increment( int * pw ) | |
{ | |
// int rv = *pw; | |
// if( rv != 0 ) ++*pw; | |
// return rv; | |
asm | |
{ | |
mov esi, [pw] | |
mov eax, dword ptr [esi] | |
L0: | |
test eax, eax | |
je L1 | |
mov ebx, eax | |
inc ebx | |
lock cmpxchg dword ptr [esi], ebx | |
jne L0 | |
L1: | |
} | |
} | |
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_exchange_and_add( &use_count_, -1 ) == 1 ) | |
{ | |
dispose(); | |
weak_release(); | |
} | |
} | |
void weak_add_ref() // nothrow | |
{ | |
atomic_increment( &weak_count_ ); | |
} | |
void weak_release() // nothrow | |
{ | |
if( atomic_exchange_and_add( &weak_count_, -1 ) == 1 ) | |
{ | |
destroy(); | |
} | |
} | |
long use_count() const // nothrow | |
{ | |
return static_cast<int const volatile &>( use_count_ ); | |
} | |
}; | |
} // namespace detail | |
} // namespace boost | |
#endif // #ifndef BOOST_SMART_PTR_DETAIL_SP_COUNTED_BASE_CW_X86_HPP_INCLUDED |