1// Declarations for hash functions. -*- C++ -*- 
2 
3// Copyright (C) 2010-2019 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 
7// terms of the GNU General Public License as published by the 
8// Free Software Foundation; either version 3, or (at your option) 
9// any later version. 
10 
11// This library is distributed in the hope that it will be useful, 
12// but WITHOUT ANY WARRANTY; without even the implied warranty of 
13// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 
14// GNU 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/** @file bits/hash_bytes.h 
26 * This is an internal header file, included by other library headers. 
27 * Do not attempt to use it directly. @headername{functional} 
28 */ 
29 
30#ifndef _HASH_BYTES_H 
31#define _HASH_BYTES_H 1 
32 
33#pragma GCC system_header 
34 
35#include <bits/c++config.h> 
36 
37namespace std 
38{ 
39_GLIBCXX_BEGIN_NAMESPACE_VERSION 
40 
41 // Hash function implementation for the nontrivial specialization. 
42 // All of them are based on a primitive that hashes a pointer to a 
43 // byte array. The actual hash algorithm is not guaranteed to stay 
44 // the same from release to release -- it may be updated or tuned to 
45 // improve hash quality or speed. 
46 size_t 
47 _Hash_bytes(const void* __ptr, size_t __len, size_t __seed); 
48 
49 // A similar hash primitive, using the FNV hash algorithm. This 
50 // algorithm is guaranteed to stay the same from release to release. 
51 // (although it might not produce the same values on different 
52 // machines.) 
53 size_t 
54 _Fnv_hash_bytes(const void* __ptr, size_t __len, size_t __seed); 
55 
56_GLIBCXX_END_NAMESPACE_VERSION 
57} // namespace 
58 
59#endif 
60