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1 // Declarations for hash functions. -*- C++ -*-
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2
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145
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3 // Copyright (C) 2010-2020 Free Software Foundation, Inc.
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111
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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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