libstdc++
hash_bytes.h
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1 // Declarations for hash functions. -*- C++ -*-
2 
3 // Copyright (C) 2010-2021 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 
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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 
37 namespace 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
ISO C++ entities toplevel namespace is std.