78 lines
1.5 KiB
C++
78 lines
1.5 KiB
C++
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#ifndef BOOST_SMART_PTR_DETAIL_ATOMIC_COUNT_GCC_X86_HPP_INCLUDED
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#define BOOST_SMART_PTR_DETAIL_ATOMIC_COUNT_GCC_X86_HPP_INCLUDED
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//
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// boost/detail/atomic_count_gcc_x86.hpp
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//
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// atomic_count for g++ on 486+/AMD64
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//
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// Copyright 2007 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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namespace boost
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{
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namespace detail
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{
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class atomic_count
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{
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public:
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explicit atomic_count( long v ) : value_( static_cast< int >( v ) ) {}
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long operator++()
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{
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return atomic_exchange_and_add( &value_, +1 ) + 1;
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}
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long operator--()
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{
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return atomic_exchange_and_add( &value_, -1 ) - 1;
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}
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operator long() const
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{
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return atomic_exchange_and_add( &value_, 0 );
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}
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private:
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atomic_count(atomic_count const &);
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atomic_count & operator=(atomic_count const &);
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mutable int value_;
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private:
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static 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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"1"( dv ): // inputs (%2 == %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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};
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} // namespace detail
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} // namespace boost
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#endif // #ifndef BOOST_SMART_PTR_DETAIL_ATOMIC_COUNT_GCC_X86_HPP_INCLUDED
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