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- #ifndef BOOST_SMART_PTR_DETAIL_ATOMIC_COUNT_GCC_X86_HPP_INCLUDED
- #define BOOST_SMART_PTR_DETAIL_ATOMIC_COUNT_GCC_X86_HPP_INCLUDED
- //
- // boost/detail/atomic_count_gcc_x86.hpp
- //
- // atomic_count for g++ on 486+/AMD64
- //
- // Copyright 2007 Peter Dimov
- //
- // 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)
- //
- namespace boost
- {
- namespace detail
- {
- class atomic_count
- {
- public:
- explicit atomic_count( long v ) : value_( static_cast< int >( v ) ) {}
- long operator++()
- {
- return atomic_exchange_and_add( &value_, +1 ) + 1;
- }
- long operator--()
- {
- return atomic_exchange_and_add( &value_, -1 ) - 1;
- }
- operator long() const
- {
- return atomic_exchange_and_add( &value_, 0 );
- }
- private:
- atomic_count(atomic_count const &);
- atomic_count & operator=(atomic_count const &);
- mutable int value_;
- private:
- static int atomic_exchange_and_add( int * pw, int dv )
- {
- // int r = *pw;
- // *pw += dv;
- // return r;
- int r;
- __asm__ __volatile__
- (
- "lock\n\t"
- "xadd %1, %0":
- "+m"( *pw ), "=r"( r ): // outputs (%0, %1)
- "1"( dv ): // inputs (%2 == %1)
- "memory", "cc" // clobbers
- );
- return r;
- }
- };
- } // namespace detail
- } // namespace boost
- #endif // #ifndef BOOST_SMART_PTR_DETAIL_ATOMIC_COUNT_GCC_X86_HPP_INCLUDED
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