175 lines
3.7 KiB
Plaintext
175 lines
3.7 KiB
Plaintext
#ifndef BOOST_SMART_PTR_DETAIL_SP_COUNTED_BASE_GCC_X86_HPP_INCLUDED
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#define BOOST_SMART_PTR_DETAIL_SP_COUNTED_BASE_GCC_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_gcc_x86.hpp - g++ on 486+ or AMD64
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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 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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int r;
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__asm__ __volatile__
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(
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"lock\n\t"
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"xadd %1, %0":
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"=m"( *pw ), "=r"( r ): // outputs (%0, %1)
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"m"( *pw ), "1"( dv ): // inputs (%2, %3 == %1)
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"memory", "cc" // clobbers
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);
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return r;
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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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"lock\n\t"
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"incl %0":
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"=m"( *pw ): // output (%0)
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"m"( *pw ): // input (%1)
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"cc" // clobbers
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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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int rv, tmp;
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__asm__
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(
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"movl %0, %%eax\n\t"
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"0:\n\t"
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"test %%eax, %%eax\n\t"
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"je 1f\n\t"
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"movl %%eax, %2\n\t"
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"incl %2\n\t"
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"lock\n\t"
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"cmpxchgl %2, %0\n\t"
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"jne 0b\n\t"
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"1:":
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"=m"( *pw ), "=&a"( rv ), "=&r"( tmp ): // outputs (%0, %1, %2)
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"m"( *pw ): // input (%3)
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"cc" // clobbers
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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_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_SMART_PTR_DETAIL_SP_COUNTED_BASE_GCC_X86_HPP_INCLUDED
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