src/cx/hash_key.h

Sun, 23 Oct 2022 16:57:10 +0200

author
Mike Becker <universe@uap-core.de>
date
Sun, 23 Oct 2022 16:57:10 +0200
changeset 597
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parent 563
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child 603
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permissions
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#217 cover cx_strcat macro

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1 /*
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2 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS HEADER.
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3 *
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4 * Copyright 2021 Mike Becker, Olaf Wintermann All rights reserved.
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5 *
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6 * Redistribution and use in source and binary forms, with or without
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7 * modification, are permitted provided that the following conditions are met:
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8 *
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9 * 1. Redistributions of source code must retain the above copyright
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10 * notice, this list of conditions and the following disclaimer.
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11 *
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12 * 2. Redistributions in binary form must reproduce the above copyright
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13 * notice, this list of conditions and the following disclaimer in the
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14 * documentation and/or other materials provided with the distribution.
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15 *
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16 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
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17 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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18 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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19 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
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20 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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21 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
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22 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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23 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
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24 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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25 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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26 * POSSIBILITY OF SUCH DAMAGE.
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27 */
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28 /**
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29 * \file hash_key.h
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30 * \brief Interface for map implementations.
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31 * \author Mike Becker
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32 * \author Olaf Wintermann
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33 * \version 3.0
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34 * \copyright 2-Clause BSD License
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35 */
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36
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37
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38 #ifndef UCX_HASH_KEY_H
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39 #define UCX_HASH_KEY_H
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40
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41 #include "stddef.h"
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42
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43 #ifdef __cplusplus
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44 extern "C" {
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45 #endif
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46
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47 /** Internal structure for a key within a hash map. */
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48 struct cx_hash_key_s {
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49 /** The key data. */
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50 union {
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51 unsigned char *bytes;
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52 unsigned char const *cbytes;
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53 char const *cstr;
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54 char *str;
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55 void *obj;
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56 } data;
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57 /**
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58 * The key data length.
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59 */
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60 size_t len;
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61 /** The hash value of the key data. */
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62 unsigned hash;
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63 };
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64
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65 /**
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66 * Type for a hash key.
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67 */
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68 typedef struct cx_hash_key_s CxHashKey;
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69
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70 /**
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71 * Computes a murmur hash-2.
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72 *
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73 * You need to initialize data and len in the key struct.
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74 * The hash is then directly written to that struct.
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75 *
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76 * @param key the key, the hash shall be computed for
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77 */
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78 void cx_hash_murmur(CxHashKey *key);
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79
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80 /**
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81 * Computes a hash key from a string.
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82 *
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83 * The string needs to be zero-terminated.
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84 *
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85 * @param str the string
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86 * @return the hash key
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87 */
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88 __attribute__((__warn_unused_result__))
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89 CxHashKey cx_hash_key_str(char const *str);
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90
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91 /**
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92 * Computes a hash key from a byte array.
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93 *
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94 * @param bytes the array
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95 * @param len the length
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96 * @return the hash key
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97 */
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98 __attribute__((__warn_unused_result__))
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99 CxHashKey cx_hash_key_bytes(
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100 unsigned char const *bytes,
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101 size_t len
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102 );
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103
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104 /**
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105 * Computes a hash key for an arbitrary object.
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106 *
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107 * The computation uses the in-memory representation that might not be
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108 * the same on different platforms. Therefore, this hash should not be
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109 * used for data exchange with different machines.
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110 *
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111 * @param obj a pointer to an arbitrary object
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112 * @param len the length of object in memory
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113 * @return the hash key
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114 */
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115 __attribute__((__warn_unused_result__))
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116 CxHashKey cx_hash_key(
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117 void *obj,
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118 size_t len
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119 );
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120
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121 #ifdef __cplusplus
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122 } // extern "C"
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123 #endif
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124
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125 #endif /* UCX_HASH_KEY_H */

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