| #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 |