epoc32/include/stdapis/boost/detail/sp_counted_base_cw_x86.hpp
author William Roberts <williamr@symbian.org>
Wed, 31 Mar 2010 12:33:34 +0100
branchSymbian3
changeset 4 837f303aceeb
permissions -rw-r--r--
Current Symbian^3 public API header files (from PDK 3.0.h)
This is the epoc32/include tree with the "platform" subtrees removed, and
all but a selected few mbg and rsg files removed.
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#ifndef BOOST_DETAIL_SP_COUNTED_BASE_CW_X86_HPP_INCLUDED
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#define BOOST_DETAIL_SP_COUNTED_BASE_CW_X86_HPP_INCLUDED
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// MS compatible compilers support #pragma once
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#if defined(_MSC_VER) && (_MSC_VER >= 1020)
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# pragma once
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#endif
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//
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//  detail/sp_counted_base_cw_x86.hpp - CodeWarrion on 486+
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//
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//  Copyright (c) 2001, 2002, 2003 Peter Dimov and Multi Media Ltd.
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//  Copyright 2004-2005 Peter Dimov
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//  Copyright 2005 Rene Rivera
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//
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//  Distributed under the Boost Software License, Version 1.0. (See
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//  accompanying file LICENSE_1_0.txt or copy at
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//  http://www.boost.org/LICENSE_1_0.txt)
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//
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//
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//  Lock-free algorithm by Alexander Terekhov
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//
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//  Thanks to Ben Hitchings for the #weak + (#shared != 0)
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//  formulation
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//
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#include <typeinfo>
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namespace boost
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{
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namespace detail
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{
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inline int atomic_exchange_and_add( int * pw, int dv )
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{
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    // int r = *pw;
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    // *pw += dv;
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    // return r;
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    asm
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    {
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        mov esi, [pw]
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        mov eax, dv
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        lock xadd dword ptr [esi], eax
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    }
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}
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inline void atomic_increment( int * pw )
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{
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    //atomic_exchange_and_add( pw, 1 );
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    asm
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    {
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        mov esi, [pw]
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        lock inc dword ptr [esi]
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    }
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}
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inline int atomic_conditional_increment( int * pw )
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{
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    // int rv = *pw;
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    // if( rv != 0 ) ++*pw;
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    // return rv;
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    asm
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    {
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        mov esi, [pw]
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        mov eax, dword ptr [esi]
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    L0:
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        test eax, eax
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        je L1
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        mov ebx, eax
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        inc ebx
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        lock cmpxchg dword ptr [esi], ebx
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        jne L0
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    L1:
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    }
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}
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class sp_counted_base
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{
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private:
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    sp_counted_base( sp_counted_base const & );
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    sp_counted_base & operator= ( sp_counted_base const & );
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    int use_count_;        // #shared
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    int weak_count_;       // #weak + (#shared != 0)
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public:
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    sp_counted_base(): use_count_( 1 ), weak_count_( 1 )
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    {
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    }
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    virtual ~sp_counted_base() // nothrow
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    {
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    }
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    // dispose() is called when use_count_ drops to zero, to release
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    // the resources managed by *this.
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    virtual void dispose() = 0; // nothrow
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    // destroy() is called when weak_count_ drops to zero.
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    virtual void destroy() // nothrow
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    {
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        delete this;
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    }
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    virtual void * get_deleter( std::type_info const & ti ) = 0;
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    void add_ref_copy()
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    {
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        atomic_increment( &use_count_ );
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    }
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    bool add_ref_lock() // true on success
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    {
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        return atomic_conditional_increment( &use_count_ ) != 0;
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    }
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    void release() // nothrow
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    {
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        if( atomic_exchange_and_add( &use_count_, -1 ) == 1 )
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        {
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            dispose();
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            weak_release();
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        }
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    }
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    void weak_add_ref() // nothrow
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    {
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        atomic_increment( &weak_count_ );
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    }
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    void weak_release() // nothrow
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    {
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        if( atomic_exchange_and_add( &weak_count_, -1 ) == 1 )
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        {
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            destroy();
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        }
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    }
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    long use_count() const // nothrow
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    {
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        return static_cast<int const volatile &>( use_count_ );
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    }
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};
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} // namespace detail
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} // namespace boost
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#endif  // #ifndef BOOST_DETAIL_SP_COUNTED_BASE_GCC_X86_HPP_INCLUDED