1 // -*- C++ -*- 2 3 // Copyright (C) 2005, 2006, 2009 Free Software Foundation, Inc. 4 // 5 // This file is part of the GNU ISO C++ Library. This library is free 6 // software; you can redistribute it and/or modify it under the terms 7 // of the GNU General Public License as published by the Free Software 8 // Foundation; either version 3, or (at your option) any later 9 // version. 10 11 // This library is distributed in the hope that it will be useful, but 12 // WITHOUT ANY WARRANTY; without even the implied warranty of 13 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 14 // General Public License for more details. 15 16 // Under Section 7 of GPL version 3, you are granted additional 17 // permissions described in the GCC Runtime Library Exception, version 18 // 3.1, as published by the Free Software Foundation. 19 20 // You should have received a copy of the GNU General Public License and 21 // a copy of the GCC Runtime Library Exception along with this program; 22 // see the files COPYING3 and COPYING.RUNTIME respectively. If not, see 23 // <http://www.gnu.org/licenses/>. 24 25 // Copyright (C) 2004 Ami Tavory and Vladimir Dreizin, IBM-HRL. 26 27 // Permission to use, copy, modify, sell, and distribute this software 28 // is hereby granted without fee, provided that the above copyright 29 // notice appears in all copies, and that both that copyright notice 30 // and this permission notice appear in supporting documentation. None 31 // of the above authors, nor IBM Haifa Research Laboratories, make any 32 // representation about the suitability of this software for any 33 // purpose. It is provided "as is" without express or implied 34 // warranty. 35 36 /** 37 * @file mask_based_range_hashing.hpp 38 * Contains a range hashing policy base. 39 */ 40 41 #ifndef PB_DS_MASK_BASED_RANGE_HASHING_HPP 42 #define PB_DS_MASK_BASED_RANGE_HASHING_HPP 43 44 namespace __gnu_pbds 45 { 46 namespace detail 47 { 48 #define PB_DS_CLASS_T_DEC template<typename Size_Type> 49 #define PB_DS_CLASS_C_DEC mask_based_range_hashing<Size_Type> 50 51 template<typename Size_Type> 52 class mask_based_range_hashing 53 { 54 protected: 55 typedef Size_Type size_type; 56 57 void 58 swap(mask_based_range_hashing& other) 59 { std::swap(m_mask, other.m_mask); } 60 61 void 62 notify_resized(size_type size); 63 64 inline size_type 65 range_hash(size_type hash) const 66 { return size_type(hash & m_mask); } 67 68 private: 69 size_type m_mask; 70 const static size_type s_num_bits_in_size_type; 71 const static size_type s_highest_bit_1; 72 }; 73 74 PB_DS_CLASS_T_DEC 75 const typename PB_DS_CLASS_C_DEC::size_type 76 PB_DS_CLASS_C_DEC::s_num_bits_in_size_type = 77 sizeof(typename PB_DS_CLASS_C_DEC::size_type) << 3; 78 79 PB_DS_CLASS_T_DEC 80 const typename PB_DS_CLASS_C_DEC::size_type PB_DS_CLASS_C_DEC::s_highest_bit_1 = static_cast<typename PB_DS_CLASS_C_DEC::size_type>(1) << (s_num_bits_in_size_type - 1); 81 82 83 PB_DS_CLASS_T_DEC 84 void 85 PB_DS_CLASS_C_DEC:: 86 notify_resized(size_type size) 87 { 88 size_type i = 0; 89 while (size ^ s_highest_bit_1) 90 { 91 size <<= 1; 92 ++i; 93 } 94 95 m_mask = 1; 96 i += 2; 97 while (i++ < s_num_bits_in_size_type) 98 m_mask = (m_mask << 1) ^ 1; 99 } 100 101 #undef PB_DS_CLASS_T_DEC 102 #undef PB_DS_CLASS_C_DEC 103 104 } // namespace detail 105 } // namespace __gnu_pbds 106 107 #endif 108
