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+#ifndef BOOST_SMART_PTR_DETAIL_SP_COUNTED_BASE_W32_HPP_INCLUDED
+#define BOOST_SMART_PTR_DETAIL_SP_COUNTED_BASE_W32_HPP_INCLUDED
+
+// MS compatible compilers support #pragma once
+
+#if defined(_MSC_VER) && (_MSC_VER >= 1020)
+# pragma once
+#endif
+
+//
+// detail/sp_counted_base_w32.hpp
+//
+// Copyright (c) 2001, 2002, 2003 Peter Dimov and Multi Media Ltd.
+// Copyright 2004-2005 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)
+//
+//
+// Lock-free algorithm by Alexander Terekhov
+//
+// Thanks to Ben Hitchings for the #weak + (#shared != 0)
+// formulation
+//
+
+#include <cutl/details/boost/detail/interlocked.hpp>
+#include <cutl/details/boost/detail/workaround.hpp>
+#include <cutl/details/boost/detail/sp_typeinfo.hpp>
+
+namespace cutl_details_boost
+{
+
+namespace detail
+{
+
+class sp_counted_base
+{
+private:
+
+ sp_counted_base( sp_counted_base const & );
+ sp_counted_base & operator= ( sp_counted_base const & );
+
+ long use_count_; // #shared
+ long weak_count_; // #weak + (#shared != 0)
+
+public:
+
+ sp_counted_base(): use_count_( 1 ), weak_count_( 1 )
+ {
+ }
+
+ virtual ~sp_counted_base() // nothrow
+ {
+ }
+
+ // dispose() is called when use_count_ drops to zero, to release
+ // the resources managed by *this.
+
+ virtual void dispose() = 0; // nothrow
+
+ // destroy() is called when weak_count_ drops to zero.
+
+ virtual void destroy() // nothrow
+ {
+ delete this;
+ }
+
+ virtual void * get_deleter( sp_typeinfo const & ti ) = 0;
+
+ void add_ref_copy()
+ {
+ BOOST_INTERLOCKED_INCREMENT( &use_count_ );
+ }
+
+ bool add_ref_lock() // true on success
+ {
+ for( ;; )
+ {
+ long tmp = static_cast< long const volatile& >( use_count_ );
+ if( tmp == 0 ) return false;
+
+#if defined( BOOST_MSVC ) && BOOST_WORKAROUND( BOOST_MSVC, == 1200 )
+
+ // work around a code generation bug
+
+ long tmp2 = tmp + 1;
+ if( BOOST_INTERLOCKED_COMPARE_EXCHANGE( &use_count_, tmp2, tmp ) == tmp2 - 1 ) return true;
+
+#else
+
+ if( BOOST_INTERLOCKED_COMPARE_EXCHANGE( &use_count_, tmp + 1, tmp ) == tmp ) return true;
+
+#endif
+ }
+ }
+
+ void release() // nothrow
+ {
+ if( BOOST_INTERLOCKED_DECREMENT( &use_count_ ) == 0 )
+ {
+ dispose();
+ weak_release();
+ }
+ }
+
+ void weak_add_ref() // nothrow
+ {
+ BOOST_INTERLOCKED_INCREMENT( &weak_count_ );
+ }
+
+ void weak_release() // nothrow
+ {
+ if( BOOST_INTERLOCKED_DECREMENT( &weak_count_ ) == 0 )
+ {
+ destroy();
+ }
+ }
+
+ long use_count() const // nothrow
+ {
+ return static_cast<long const volatile &>( use_count_ );
+ }
+};
+
+} // namespace detail
+
+} // namespace cutl_details_boost
+
+#endif // #ifndef BOOST_SMART_PTR_DETAIL_SP_COUNTED_BASE_W32_HPP_INCLUDED