comparison DEPENDENCIES/generic/include/boost/intrusive/pointer_plus_bits.hpp @ 16:2665513ce2d3

Add boost headers

+/////////////////////////////////////////////////////////////////////////////
+//
+// (C) Copyright Ion Gaztanaga  2007-2013
+//
+// 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)
+//
+// See http://www.boost.org/libs/intrusive for documentation.
+//
+/////////////////////////////////////////////////////////////////////////////
+
+#ifndef BOOST_INTRUSIVE_POINTER_PLUS_BITS_HPP
+#define BOOST_INTRUSIVE_POINTER_PLUS_BITS_HPP
+
+#include <boost/intrusive/detail/mpl.hpp> //ls_zeros
+#include <boost/intrusive/detail/assert.hpp> //BOOST_INTRUSIVE_INVARIANT_ASSERT
+
+namespace boost {
+namespace intrusive {
+
+//!This trait class is used to know if a pointer
+//!can embed extra bits of information if
+//!it's going to be used to point to objects
+//!with an alignment of "Alignment" bytes.
+template<class VoidPointer, std::size_t Alignment>
+struct max_pointer_plus_bits
+{
+   static const std::size_t value = 0;
+};
+
+//!This is a specialization for raw pointers.
+//!Raw pointers can embed extra bits in the lower bits
+//!if the alignment is multiple of 2pow(NumBits).
+template<std::size_t Alignment>
+struct max_pointer_plus_bits<void*, Alignment>
+{
+   static const std::size_t value = detail::ls_zeros<Alignment>::value;
+};
+
+//!This is class that is supposed to have static methods
+//!to embed extra bits of information in a pointer.
+//!This is a declaration and there is no default implementation,
+//!because operations to embed the bits change with every pointer type.
+//!
+//!An implementation that detects that a pointer type whose
+//!has_pointer_plus_bits<>::value is non-zero can make use of these
+//!operations to embed the bits in the pointer.
+template<class Pointer, std::size_t NumBits>
+struct pointer_plus_bits
+   #ifdef BOOST_INTRUSIVE_DOXYGEN_INVOKED
+   {}
+   #endif
+;
+
+//!This is the specialization to embed extra bits of information
+//!in a raw pointer. The extra bits are stored in the lower bits of the pointer.
+template<class T, std::size_t NumBits>
+struct pointer_plus_bits<T*, NumBits>
+{
+   static const std::size_t Mask = ((std::size_t(1u) << NumBits) - 1);
+   typedef T*        pointer;
+
+   static pointer get_pointer(pointer n)
+   {  return pointer(std::size_t(n) & ~Mask);  }
+
+   static void set_pointer(pointer &n, pointer p)
+   {
+      BOOST_INTRUSIVE_INVARIANT_ASSERT(0 == (std::size_t(p) & Mask));
+      n = pointer(std::size_t(p) | (std::size_t(n) & Mask));
+   }
+
+   static std::size_t get_bits(pointer n)
+   {  return (std::size_t(n) & Mask);  }
+
+   static void set_bits(pointer &n, std::size_t c)
+   {
+      BOOST_INTRUSIVE_INVARIANT_ASSERT(c <= Mask);
+      n = pointer(std::size_t(get_pointer(n)) | c);
+   }
+};
+
+} //namespace intrusive
+} //namespace boost
+
+#endif //BOOST_INTRUSIVE_POINTER_PLUS_BITS_HPP