1 | /*- |
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2 | * Copyright (c) 2001 Tobias Weingartner |
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3 | * All rights reserved. |
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4 | * |
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5 | * Redistribution and use in source and binary forms, with or without |
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6 | * modification, are permitted provided that the following conditions |
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7 | * are met: |
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8 | * 1. Redistributions of source code must retain the above copyright |
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9 | * notice, this list of conditions and the following disclaimer. |
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10 | * 2. Redistributions in binary form must reproduce the above copyright |
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11 | * notice, this list of conditions and the following disclaimer in the |
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12 | * documentation and/or other materials provided with the distribution. |
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13 | * |
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14 | * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR |
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15 | * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES |
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16 | * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. |
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17 | * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, |
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18 | * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT |
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19 | * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, |
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20 | * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY |
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21 | * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT |
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22 | * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF |
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23 | * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. |
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24 | * |
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25 | * $OpenBSD: hash.h,v 1.4 2004/05/25 18:37:23 jmc Exp $ |
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26 | * $FreeBSD$ |
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27 | */ |
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28 | |
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29 | #ifndef _SYS_HASH_H_ |
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30 | #define _SYS_HASH_H_ |
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31 | #include <rtems/bsd/sys/types.h> |
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32 | |
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33 | /* Convenience */ |
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34 | #ifndef HASHINIT |
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35 | #define HASHINIT 5381 |
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36 | #define HASHSTEP(x,c) (((x << 5) + x) + (c)) |
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37 | #endif |
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38 | |
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39 | /* |
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40 | * Return a 32-bit hash of the given buffer. The init |
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41 | * value should be 0, or the previous hash value to extend |
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42 | * the previous hash. |
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43 | */ |
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44 | static __inline uint32_t |
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45 | hash32_buf(const void *buf, size_t len, uint32_t hash) |
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46 | { |
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47 | const unsigned char *p = buf; |
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48 | |
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49 | while (len--) |
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50 | hash = HASHSTEP(hash, *p++); |
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51 | |
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52 | return hash; |
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53 | } |
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54 | |
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55 | /* |
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56 | * Return a 32-bit hash of the given string. |
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57 | */ |
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58 | static __inline uint32_t |
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59 | hash32_str(const void *buf, uint32_t hash) |
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60 | { |
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61 | const unsigned char *p = buf; |
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62 | |
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63 | while (*p) |
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64 | hash = HASHSTEP(hash, *p++); |
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65 | |
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66 | return hash; |
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67 | } |
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68 | |
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69 | /* |
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70 | * Return a 32-bit hash of the given string, limited by N. |
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71 | */ |
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72 | static __inline uint32_t |
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73 | hash32_strn(const void *buf, size_t len, uint32_t hash) |
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74 | { |
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75 | const unsigned char *p = buf; |
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76 | |
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77 | while (*p && len--) |
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78 | hash = HASHSTEP(hash, *p++); |
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79 | |
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80 | return hash; |
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81 | } |
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82 | |
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83 | /* |
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84 | * Return a 32-bit hash of the given string terminated by C, |
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85 | * (as well as 0). This is mainly here as a helper for the |
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86 | * namei() hashing of path name parts. |
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87 | */ |
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88 | static __inline uint32_t |
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89 | hash32_stre(const void *buf, int end, const char **ep, uint32_t hash) |
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90 | { |
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91 | const unsigned char *p = buf; |
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92 | |
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93 | while (*p && (*p != end)) |
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94 | hash = HASHSTEP(hash, *p++); |
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95 | |
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96 | if (ep) |
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97 | *ep = p; |
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98 | |
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99 | return hash; |
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100 | } |
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101 | |
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102 | /* |
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103 | * Return a 32-bit hash of the given string, limited by N, |
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104 | * and terminated by C (as well as 0). This is mainly here |
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105 | * as a helper for the namei() hashing of path name parts. |
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106 | */ |
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107 | static __inline uint32_t |
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108 | hash32_strne(const void *buf, size_t len, int end, const char **ep, |
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109 | uint32_t hash) |
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110 | { |
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111 | const unsigned char *p = buf; |
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112 | |
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113 | while (*p && (*p != end) && len--) |
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114 | hash = HASHSTEP(hash, *p++); |
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115 | |
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116 | if (ep) |
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117 | *ep = p; |
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118 | |
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119 | return hash; |
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120 | } |
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121 | #endif /* !_SYS_HASH_H_ */ |
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