1// -*- C++ -*-
2
3// Copyright (C) 2005-2022 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 hash_prime_size_policy_imp.hpp
38 * Contains a resize size policy implementation.
39 */
40
41#ifdef PB_DS_CLASS_C_DEC
42
43#pragma GCC system_header
44
45namespace detail
46{
47  enum
48    {
49      num_distinct_sizes_16_bit = 14,
50      num_distinct_sizes_32_bit = 30,
51      num_distinct_sizes_64_bit = 62,
52      // The number of values is limited by the width of size_t.
53      // Maybe we could just use (__SIZE_WIDTH__ - 2) here.
54#if __SIZE_WIDTH__ >= 64
55      num_distinct_sizes =  num_distinct_sizes_64_bit
56#elif __SIZE_WIDTH__ >= 32
57      num_distinct_sizes =  num_distinct_sizes_32_bit
58#else
59      num_distinct_sizes =  num_distinct_sizes_16_bit
60#endif
61    };
62
63  // Originally taken from the SGI implementation; acknowledged in the docs.
64  // Further modified (for 64 bits) from tr1's hashtable.
65  static const std::size_t g_a_sizes[num_distinct_sizes] =
66    {
67      /* 0     */              5ul,
68      /* 1     */              11ul,
69      /* 2     */              23ul,
70      /* 3     */              47ul,
71      /* 4     */              97ul,
72      /* 5     */              199ul,
73      /* 6     */              409ul,
74      /* 7     */              823ul,
75      /* 8     */              1741ul,
76      /* 9     */              3469ul,
77      /* 10    */              6949ul,
78      /* 11    */              14033ul,
79      /* 12    */              28411ul,
80      /* 13    */              57557ul,
81#if __SIZE_WIDTH__ >= 32
82      /* 14    */              116731ul,
83      /* 15    */              236897ul,
84      /* 16    */              480881ul,
85      /* 17    */              976369ul,
86      /* 18    */              1982627ul,
87      /* 19    */              4026031ul,
88      /* 20    */              8175383ul,
89      /* 21    */              16601593ul,
90      /* 22    */              33712729ul,
91      /* 23    */              68460391ul,
92      /* 24    */              139022417ul,
93      /* 25    */              282312799ul,
94      /* 26    */              573292817ul,
95      /* 27    */              1164186217ul,
96      /* 28    */              2364114217ul,
97      /* 29    */              4294967291ul,
98#if __SIZE_WIDTH__ >= 64
99      /* 30    */ (std::size_t)8589934583ull,
100      /* 31    */ (std::size_t)17179869143ull,
101      /* 32    */ (std::size_t)34359738337ull,
102      /* 33    */ (std::size_t)68719476731ull,
103      /* 34    */ (std::size_t)137438953447ull,
104      /* 35    */ (std::size_t)274877906899ull,
105      /* 36    */ (std::size_t)549755813881ull,
106      /* 37    */ (std::size_t)1099511627689ull,
107      /* 38    */ (std::size_t)2199023255531ull,
108      /* 39    */ (std::size_t)4398046511093ull,
109      /* 40    */ (std::size_t)8796093022151ull,
110      /* 41    */ (std::size_t)17592186044399ull,
111      /* 42    */ (std::size_t)35184372088777ull,
112      /* 43    */ (std::size_t)70368744177643ull,
113      /* 44    */ (std::size_t)140737488355213ull,
114      /* 45    */ (std::size_t)281474976710597ull,
115      /* 46    */ (std::size_t)562949953421231ull,
116      /* 47    */ (std::size_t)1125899906842597ull,
117      /* 48    */ (std::size_t)2251799813685119ull,
118      /* 49    */ (std::size_t)4503599627370449ull,
119      /* 50    */ (std::size_t)9007199254740881ull,
120      /* 51    */ (std::size_t)18014398509481951ull,
121      /* 52    */ (std::size_t)36028797018963913ull,
122      /* 53    */ (std::size_t)72057594037927931ull,
123      /* 54    */ (std::size_t)144115188075855859ull,
124      /* 55    */ (std::size_t)288230376151711717ull,
125      /* 56    */ (std::size_t)576460752303423433ull,
126      /* 57    */ (std::size_t)1152921504606846883ull,
127      /* 58    */ (std::size_t)2305843009213693951ull,
128      /* 59    */ (std::size_t)4611686018427387847ull,
129      /* 60    */ (std::size_t)9223372036854775783ull,
130      /* 61    */ (std::size_t)18446744073709551557ull,
131#endif
132#endif
133    };
134
135} // namespace detail
136
137PB_DS_CLASS_T_DEC
138inline
139PB_DS_CLASS_C_DEC::
140hash_prime_size_policy(size_type n) : m_start_size(n)
141{ m_start_size = get_nearest_larger_size(n); }
142
143PB_DS_CLASS_T_DEC
144inline void
145PB_DS_CLASS_C_DEC::
146swap(PB_DS_CLASS_C_DEC& other)
147{ std::swap(m_start_size, other.m_start_size); }
148
149PB_DS_CLASS_T_DEC
150inline PB_DS_CLASS_C_DEC::size_type
151PB_DS_CLASS_C_DEC::
152get_nearest_larger_size(size_type n) const
153{
154  const std::size_t* const p_upper = std::upper_bound(detail::g_a_sizes,
155		     detail::g_a_sizes + detail::num_distinct_sizes, n);
156
157  if (p_upper == detail::g_a_sizes + detail::num_distinct_sizes)
158    __throw_resize_error();
159  return *p_upper;
160}
161
162PB_DS_CLASS_T_DEC
163inline PB_DS_CLASS_C_DEC::size_type
164PB_DS_CLASS_C_DEC::
165get_nearest_smaller_size(size_type n) const
166{
167  const std::size_t* p_lower = std::lower_bound(detail::g_a_sizes,
168		       detail::g_a_sizes + detail::num_distinct_sizes, n);
169
170  if (*p_lower >= n &&  p_lower != detail::g_a_sizes)
171    --p_lower;
172  if (*p_lower < m_start_size)
173    return m_start_size;
174  return *p_lower;
175}
176#endif
177