Incomplete work for using Boost.Polygon to compute medial axis

xs/src/boost/smart_ptr/detail/atomic_count_gcc.hpp

@@ -0,0 +1,72 @@
+#ifndef BOOST_SMART_PTR_DETAIL_ATOMIC_COUNT_GCC_HPP_INCLUDED
+#define BOOST_SMART_PTR_DETAIL_ATOMIC_COUNT_GCC_HPP_INCLUDED
+
+//
+//  boost/detail/atomic_count_gcc.hpp
+//
+//  atomic_count for GNU libstdc++ v3
+//
+//  http://gcc.gnu.org/onlinedocs/porting/Thread-safety.html
+//
+//  Copyright (c) 2001, 2002 Peter Dimov and Multi Media Ltd.
+//  Copyright (c) 2002 Lars Gullik Bjønnes <larsbj@lyx.org>
+//  Copyright 2003-2005 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)
+//
+
+#if __GNUC__ * 100 + __GNUC_MINOR__ >= 402
+# include <ext/atomicity.h> 
+#else 
+# include <bits/atomicity.h>
+#endif
+
+namespace boost
+{
+
+namespace detail
+{
+
+#if defined(__GLIBCXX__) // g++ 3.4+
+
+using __gnu_cxx::__atomic_add;
+using __gnu_cxx::__exchange_and_add;
+
+#endif
+
+class atomic_count
+{
+public:
+
+    explicit atomic_count( long v ) : value_( v ) {}
+
+    long operator++()
+    {
+        return __exchange_and_add( &value_, +1 ) + 1;
+    }
+
+    long operator--()
+    {
+        return __exchange_and_add( &value_, -1 ) - 1;
+    }
+
+    operator long() const
+    {
+        return __exchange_and_add( &value_, 0 );
+    }
+
+private:
+
+    atomic_count(atomic_count const &);
+    atomic_count & operator=(atomic_count const &);
+
+    mutable _Atomic_word value_;
+};
+
+} // namespace detail
+
+} // namespace boost
+
+#endif // #ifndef BOOST_SMART_PTR_DETAIL_ATOMIC_COUNT_GCC_HPP_INCLUDED