1 /*-
2 * Copyright (c) 2001 Tobias Weingartner
3 * All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 * 1. Redistributions of source code must retain the above copyright
9 * notice, this list of conditions and the following disclaimer.
10 * 2. Redistributions in binary form must reproduce the above copyright
11 * notice, this list of conditions and the following disclaimer in the
12 * documentation and/or other materials provided with the distribution.
13 *
14 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
15 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
16 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
17 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
18 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
19 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
20 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
21 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
22 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
23 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
24 *
25 * $OpenBSD: hash.h,v 1.4 2004/05/25 18:37:23 jmc Exp $
26 * $FreeBSD: src/sys/sys/hash.h,v 1.3 2007/04/09 22:55:14 thompsa Exp $
27 */
28
29 #ifndef _SYS_HASH_H_
30 #define _SYS_HASH_H_
31 #include <sys/types.h>
32
33 /* Convenience */
34 #ifndef HASHINIT
35 #define HASHINIT 5381
36 #define HASHSTEP(x,c) (((x << 5) + x) + (c))
37 #endif
38
39 /*
40 * Return a 32-bit hash of the given buffer. The init
41 * value should be 0, or the previous hash value to extend
42 * the previous hash.
43 */
44 static __inline uint32_t
hash32_buf(const void * buf,size_t len,uint32_t hash)45 hash32_buf(const void *buf, size_t len, uint32_t hash)
46 {
47 const unsigned char *p = buf;
48
49 while (len--)
50 hash = HASHSTEP(hash, *p++);
51
52 return hash;
53 }
54
55 /*
56 * Return a 32-bit hash of the given string.
57 */
58 static __inline uint32_t
hash32_str(const void * buf,uint32_t hash)59 hash32_str(const void *buf, uint32_t hash)
60 {
61 const unsigned char *p = buf;
62
63 while (*p)
64 hash = HASHSTEP(hash, *p++);
65
66 return hash;
67 }
68
69 /*
70 * Return a 32-bit hash of the given string, limited by N.
71 */
72 static __inline uint32_t
hash32_strn(const void * buf,size_t len,uint32_t hash)73 hash32_strn(const void *buf, size_t len, uint32_t hash)
74 {
75 const unsigned char *p = buf;
76
77 while (*p && len--)
78 hash = HASHSTEP(hash, *p++);
79
80 return hash;
81 }
82
83 /*
84 * Return a 32-bit hash of the given string terminated by C,
85 * (as well as 0). This is mainly here as a helper for the
86 * namei() hashing of path name parts.
87 */
88 static __inline uint32_t
hash32_stre(const void * buf,int end,const char ** ep,uint32_t hash)89 hash32_stre(const void *buf, int end, const char **ep, uint32_t hash)
90 {
91 const unsigned char *p = buf;
92
93 while (*p && (*p != end))
94 hash = HASHSTEP(hash, *p++);
95
96 if (ep)
97 *ep = p;
98
99 return hash;
100 }
101
102 /*
103 * Return a 32-bit hash of the given string, limited by N,
104 * and terminated by C (as well as 0). This is mainly here
105 * as a helper for the namei() hashing of path name parts.
106 */
107 static __inline uint32_t
hash32_strne(const void * buf,size_t len,int end,const char ** ep,uint32_t hash)108 hash32_strne(const void *buf, size_t len, int end, const char **ep,
109 uint32_t hash)
110 {
111 const unsigned char *p = buf;
112
113 while (*p && (*p != end) && len--)
114 hash = HASHSTEP(hash, *p++);
115
116 if (ep)
117 *ep = p;
118
119 return hash;
120 }
121
122 #endif /* !_SYS_HASH_H_ */
123