183 lines
		
	
	
		
			3.6 KiB
		
	
	
	
		
			Plaintext
		
	
	
	
	
	
			
		
		
	
	
			183 lines
		
	
	
		
			3.6 KiB
		
	
	
	
		
			Plaintext
		
	
	
	
	
	
#ifndef BOOST_SMART_PTR_DETAIL_SP_COUNTED_BASE_GCC_PPC_HPP_INCLUDED
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#define BOOST_SMART_PTR_DETAIL_SP_COUNTED_BASE_GCC_PPC_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_gcc_ppc.hpp - g++ on PowerPC
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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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//
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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 <boost/detail/sp_typeinfo.hpp>
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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 void atomic_increment( int * pw )
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{
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    // ++*pw;
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    int tmp;
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    __asm__
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    (
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        "0:\n\t"
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        "lwarx %1, 0, %2\n\t"
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        "addi %1, %1, 1\n\t"
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        "stwcx. %1, 0, %2\n\t"
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        "bne- 0b":
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        "=m"( *pw ), "=&b"( tmp ):
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        "r"( pw ), "m"( *pw ):
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        "cc"
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    );
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}
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inline int atomic_decrement( int * pw )
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{
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    // return --*pw;
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    int rv;
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    __asm__ __volatile__
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    (
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        "sync\n\t"
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        "0:\n\t"
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        "lwarx %1, 0, %2\n\t"
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        "addi %1, %1, -1\n\t"
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        "stwcx. %1, 0, %2\n\t"
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        "bne- 0b\n\t"
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        "isync":
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        "=m"( *pw ), "=&b"( rv ):
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        "r"( pw ), "m"( *pw ):
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        "memory", "cc"
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    );
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    return rv;
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}
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inline int atomic_conditional_increment( int * pw )
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{
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    // if( *pw != 0 ) ++*pw;
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    // return *pw;
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    int rv;
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    __asm__
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    (
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        "0:\n\t"
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        "lwarx %1, 0, %2\n\t"
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        "cmpwi %1, 0\n\t"
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        "beq 1f\n\t"
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        "addi %1, %1, 1\n\t"
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        "1:\n\t"
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        "stwcx. %1, 0, %2\n\t"
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        "bne- 0b":
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        "=m"( *pw ), "=&b"( rv ):
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        "r"( pw ), "m"( *pw ):
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        "cc"
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    );
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    return rv;
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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( sp_typeinfo const & ti ) = 0;
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    virtual void * get_untyped_deleter() = 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_decrement( &use_count_ ) == 0 )
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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_decrement( &weak_count_ ) == 0 )
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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_SMART_PTR_DETAIL_SP_COUNTED_BASE_GCC_PPC_HPP_INCLUDED
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