FreeBSD/Linux Kernel Cross Reference
sys/sys/hash.h
1 /*-
2 * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
3 *
4 * Copyright (c) 2001 Tobias Weingartner
5 * All rights reserved.
6 *
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions
9 * are met:
10 * 1. Redistributions of source code must retain the above copyright
11 * notice, this list of conditions and the following disclaimer.
12 * 2. Redistributions in binary form must reproduce the above copyright
13 * notice, this list of conditions and the following disclaimer in the
14 * documentation and/or other materials provided with the distribution.
15 *
16 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
17 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
18 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
19 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
20 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
21 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
22 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
23 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
24 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
25 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
26 *
27 * $OpenBSD: hash.h,v 1.4 2004/05/25 18:37:23 jmc Exp $
28 * $FreeBSD$
29 */
30
31 #ifndef _SYS_HASH_H_
32 #define _SYS_HASH_H_
33 #include <sys/types.h>
34
35 /* Convenience */
36 #ifndef HASHINIT
37 #define HASHINIT 5381
38 #define HASHSTEP(x,c) (((x << 5) + x) + (c))
39 #endif
40
41 /*
42 * Return a 32-bit hash of the given buffer. The init
43 * value should be 0, or the previous hash value to extend
44 * the previous hash.
45 */
46 static __inline uint32_t
47 hash32_buf(const void *buf, size_t len, uint32_t hash)
48 {
49 const unsigned char *p = buf;
50
51 while (len--)
52 hash = HASHSTEP(hash, *p++);
53
54 return hash;
55 }
56
57 /*
58 * Return a 32-bit hash of the given string.
59 */
60 static __inline uint32_t
61 hash32_str(const void *buf, uint32_t hash)
62 {
63 const unsigned char *p = buf;
64
65 while (*p)
66 hash = HASHSTEP(hash, *p++);
67
68 return hash;
69 }
70
71 /*
72 * Return a 32-bit hash of the given string, limited by N.
73 */
74 static __inline uint32_t
75 hash32_strn(const void *buf, size_t len, uint32_t hash)
76 {
77 const unsigned char *p = buf;
78
79 while (*p && len--)
80 hash = HASHSTEP(hash, *p++);
81
82 return hash;
83 }
84
85 /*
86 * Return a 32-bit hash of the given string terminated by C,
87 * (as well as 0). This is mainly here as a helper for the
88 * namei() hashing of path name parts.
89 */
90 static __inline uint32_t
91 hash32_stre(const void *buf, int end, const char **ep, uint32_t hash)
92 {
93 const unsigned char *p = buf;
94
95 while (*p && (*p != end))
96 hash = HASHSTEP(hash, *p++);
97
98 if (ep)
99 *ep = p;
100
101 return hash;
102 }
103
104 /*
105 * Return a 32-bit hash of the given string, limited by N,
106 * and terminated by C (as well as 0). This is mainly here
107 * as a helper for the namei() hashing of path name parts.
108 */
109 static __inline uint32_t
110 hash32_strne(const void *buf, size_t len, int end, const char **ep,
111 uint32_t hash)
112 {
113 const unsigned char *p = buf;
114
115 while (*p && (*p != end) && len--)
116 hash = HASHSTEP(hash, *p++);
117
118 if (ep)
119 *ep = p;
120
121 return hash;
122 }
123
124 #ifdef _KERNEL
125 /*
126 * Hashing function from Bob Jenkins. Implementation in libkern/jenkins_hash.c.
127 */
128 uint32_t jenkins_hash(const void *, size_t, uint32_t);
129 uint32_t jenkins_hash32(const uint32_t *, size_t, uint32_t);
130
131 uint32_t murmur3_32_hash(const void *, size_t, uint32_t);
132 uint32_t murmur3_32_hash32(const uint32_t *, size_t, uint32_t);
133
134 #endif /* _KERNEL */
135
136 #endif /* !_SYS_HASH_H_ */
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