| 1 | // Declarations for hash functions. -*- C++ -*- |
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| 2 | |
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| 3 | // Copyright (C) 2010-2021 Free Software Foundation, Inc. |
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| 4 | // |
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| 5 | // This file is part of the GNU ISO C++ Library. This library is free |
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| 6 | // software; you can redistribute it and/or modify it under the |
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| 7 | // terms of the GNU General Public License as published by the |
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| 8 | // Free Software Foundation; either version 3, or (at your option) |
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| 9 | // any later version. |
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| 10 | |
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| 11 | // This library is distributed in the hope that it will be useful, |
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| 12 | // but WITHOUT ANY WARRANTY; without even the implied warranty of |
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| 13 | // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
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| 14 | // GNU General Public License for more details. |
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| 15 | |
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| 16 | // Under Section 7 of GPL version 3, you are granted additional |
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| 17 | // permissions described in the GCC Runtime Library Exception, version |
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| 18 | // 3.1, as published by the Free Software Foundation. |
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| 19 | |
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| 20 | // You should have received a copy of the GNU General Public License and |
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| 21 | // a copy of the GCC Runtime Library Exception along with this program; |
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| 22 | // see the files COPYING3 and COPYING.RUNTIME respectively. If not, see |
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| 23 | // <http://www.gnu.org/licenses/>. |
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| 24 | |
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| 25 | /** @file bits/hash_bytes.h |
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| 26 | * This is an internal header file, included by other library headers. |
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| 27 | * Do not attempt to use it directly. @headername{functional} |
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| 28 | */ |
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| 29 | |
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| 30 | #ifndef _HASH_BYTES_H |
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| 31 | #define _HASH_BYTES_H 1 |
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| 32 | |
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| 33 | #pragma GCC system_header |
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| 34 | |
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| 35 | #include <bits/c++config.h> |
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| 36 | |
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| 37 | namespace std |
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| 38 | { |
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| 39 | _GLIBCXX_BEGIN_NAMESPACE_VERSION |
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| 40 | |
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| 41 | // Hash function implementation for the nontrivial specialization. |
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| 42 | // All of them are based on a primitive that hashes a pointer to a |
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| 43 | // byte array. The actual hash algorithm is not guaranteed to stay |
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| 44 | // the same from release to release -- it may be updated or tuned to |
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| 45 | // improve hash quality or speed. |
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| 46 | size_t |
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| 47 | _Hash_bytes(const void* __ptr, size_t __len, size_t __seed); |
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| 48 | |
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| 49 | // A similar hash primitive, using the FNV hash algorithm. This |
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| 50 | // algorithm is guaranteed to stay the same from release to release. |
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| 51 | // (although it might not produce the same values on different |
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| 52 | // machines.) |
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| 53 | size_t |
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| 54 | _Fnv_hash_bytes(const void* __ptr, size_t __len, size_t __seed); |
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| 55 | |
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| 56 | _GLIBCXX_END_NAMESPACE_VERSION |
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| 57 | } // namespace |
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| 58 | |
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| 59 | #endif |
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| 60 | |
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