Line data    Source code

       1             : // Copyright (C) 2005-2006 The Trustees of Indiana University.
       2             : 
       3             : // Distributed under the Boost Software License, Version 1.0.
       4             : // (See accompanying file LICENSE_1_0.txt or copy at
       5             : // http://www.boost.org/LICENSE_1_0.txt)
       6             : 
       7             : //  Authors: Jeremiah Willcock
       8             : //           Douglas Gregor
       9             : //           Andrew Lumsdaine
      10             : 
      11             : // Two bit per color property map
      12             : 
      13             : #ifndef BOOST_TWO_BIT_COLOR_MAP_HPP
      14             : #define BOOST_TWO_BIT_COLOR_MAP_HPP
      15             : 
      16             : #include <boost/property_map/property_map.hpp>
      17             : #include <boost/graph/properties.hpp>
      18             : #include <boost/graph/detail/mpi_include.hpp>
      19             : #include <boost/shared_array.hpp>
      20             : #include <boost/config.hpp>
      21             : #include <boost/assert.hpp>
      22             : #include <algorithm>
      23             : #include <limits>
      24             : 
      25             : namespace boost {
      26             : 
      27             : enum two_bit_color_type { 
      28             :   two_bit_white = 0, 
      29             :   two_bit_gray  = 1, 
      30             :   two_bit_green = 2, 
      31             :   two_bit_black = 3 
      32             : };
      33             : 
      34             : template <>
      35             : struct color_traits<two_bit_color_type>
      36             : {
      37           0 :   static two_bit_color_type white() { return two_bit_white; }
      38           0 :   static two_bit_color_type gray()  { return two_bit_gray; }
      39             :   static two_bit_color_type green() { return two_bit_green; }
      40           0 :   static two_bit_color_type black() { return two_bit_black; }
      41             : };
      42             : 
      43             : 
      44             : template<typename IndexMap = identity_property_map>
      45           0 : struct two_bit_color_map 
      46             : {
      47             :   std::size_t n;
      48             :   IndexMap index;
      49             :   shared_array<unsigned char> data;
      50             : 
      51             :   BOOST_STATIC_CONSTANT(int, bits_per_char = std::numeric_limits<unsigned char>::digits);
      52             :   BOOST_STATIC_CONSTANT(int, elements_per_char = bits_per_char / 2);
      53             :   typedef typename property_traits<IndexMap>::key_type key_type;
      54             :   typedef two_bit_color_type value_type;
      55             :   typedef void reference;
      56             :   typedef read_write_property_map_tag category;
      57             : 
      58           0 :   explicit two_bit_color_map(std::size_t n, const IndexMap& index = IndexMap())
      59           0 :     : n(n), index(index), data(new unsigned char[(n + elements_per_char - 1) / elements_per_char])
      60             :   {
      61             :     // Fill to white
      62           0 :     std::fill(data.get(), data.get() + (n + elements_per_char - 1) / elements_per_char, 0);
      63           0 :   }
      64             : };
      65             : 
      66             : template<typename IndexMap>
      67             : inline two_bit_color_type
      68           0 : get(const two_bit_color_map<IndexMap>& pm, 
      69             :     typename property_traits<IndexMap>::key_type key) 
      70             : {
      71             :   BOOST_STATIC_CONSTANT(int, elements_per_char = two_bit_color_map<IndexMap>::elements_per_char);
      72           0 :   typename property_traits<IndexMap>::value_type i = get(pm.index, key);
      73           0 :   BOOST_ASSERT ((std::size_t)i < pm.n);
      74           0 :   std::size_t byte_num = i / elements_per_char;
      75           0 :   std::size_t bit_position = ((i % elements_per_char) * 2);
      76           0 :   return two_bit_color_type((pm.data.get()[byte_num] >> bit_position) & 3);
      77             : }
      78             : 
      79             : template<typename IndexMap>
      80             : inline void
      81           0 : put(const two_bit_color_map<IndexMap>& pm, 
      82             :     typename property_traits<IndexMap>::key_type key,
      83             :     two_bit_color_type value)
      84             : {
      85             :   BOOST_STATIC_CONSTANT(int, elements_per_char = two_bit_color_map<IndexMap>::elements_per_char);
      86           0 :   typename property_traits<IndexMap>::value_type i = get(pm.index, key);
      87           0 :   BOOST_ASSERT ((std::size_t)i < pm.n);
      88           0 :   BOOST_ASSERT (value >= 0 && value < 4);
      89           0 :   std::size_t byte_num = i / elements_per_char;
      90           0 :   std::size_t bit_position = ((i % elements_per_char) * 2);
      91           0 :     pm.data.get()[byte_num] =
      92             :       (unsigned char)
      93           0 :         ((pm.data.get()[byte_num] & ~(3 << bit_position))
      94           0 :          | (value << bit_position));
      95           0 : }
      96             : 
      97             : template<typename IndexMap>
      98             : inline two_bit_color_map<IndexMap>
      99             : make_two_bit_color_map(std::size_t n, const IndexMap& index_map)
     100             : {
     101             :   return two_bit_color_map<IndexMap>(n, index_map);
     102             : }
     103             : 
     104             : } // end namespace boost
     105             : 
     106             : #include BOOST_GRAPH_MPI_INCLUDE(<boost/graph/distributed/two_bit_color_map.hpp>)
     107             : 
     108             : #endif // BOOST_TWO_BIT_COLOR_MAP_HPP