FreeBSD/Linux Kernel Cross Reference
sys/sys/hash.h
1 /* $NetBSD: hash.h,v 1.1 2001/12/05 06:51:55 lukem Exp $ */
2
3 /*-
4 * Copyright (c) 2001 The NetBSD Foundation, Inc.
5 * All rights reserved.
6 *
7 * This code is derived from software contributed to The NetBSD Foundation
8 * by Luke Mewburn.
9 *
10 * Redistribution and use in source and binary forms, with or without
11 * modification, are permitted provided that the following conditions
12 * are met:
13 * 1. Redistributions of source code must retain the above copyright
14 * notice, this list of conditions and the following disclaimer.
15 * 2. Redistributions in binary form must reproduce the above copyright
16 * notice, this list of conditions and the following disclaimer in the
17 * documentation and/or other materials provided with the distribution.
18 * 3. All advertising materials mentioning features or use of this software
19 * must display the following acknowledgement:
20 * This product includes software developed by the NetBSD
21 * Foundation, Inc. and its contributors.
22 * 4. Neither the name of The NetBSD Foundation nor the names of its
23 * contributors may be used to endorse or promote products derived
24 * from this software without specific prior written permission.
25 *
26 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
27 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
28 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
29 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
30 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
31 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
32 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
33 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
34 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
35 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
36 * POSSIBILITY OF SUCH DAMAGE.
37 */
38
39 #ifndef _SYS_HASH_H_
40 #define _SYS_HASH_H_
41
42 #include <sys/types.h>
43 #ifdef __HAVE_MACHINE_HASH_H
44 #include <machine/hash.h>
45 #endif
46
47
48 #ifndef __HAVE_HASH32_BUF /* not overridden by MD hash */
49
50 #define HASH32_BUF_INIT 5381
51
52 /*
53 * uint32_t
54 * hash32_buf(const void *buf, size_t len, uint32_t hash)
55 * return a 32 bit hash of the binary buffer buf (size len),
56 * seeded with an initial hash value of hash (usually HASH32_BUF_INIT).
57 */
58 static __inline uint32_t
59 hash32_buf(const void *buf, size_t len, uint32_t hash)
60 {
61 const uint8_t *s = buf;
62
63 while (len-- != 0) /* "nemesi": k=257, r=r*257 */
64 hash = hash * 257 + *s++;
65 return (hash * 257);
66 }
67 #endif /* __HAVE_HASH32_BUF */
68
69
70 #ifndef __HAVE_HASH32_STR /* not overridden by MD hash */
71
72 #define HASH32_STR_INIT 5381
73 /*
74 * uint32_t
75 * hash32_str(const void *buf, uint32_t hash)
76 * return a 32 bit hash of NUL terminated ASCII string buf,
77 * seeded with an initial hash value of hash (usually HASH32_STR_INIT).
78 */
79 static __inline uint32_t
80 hash32_str(const void *buf, uint32_t hash)
81 {
82 const uint8_t *s = buf;
83 uint8_t c;
84
85 while ((c = *s++) != 0)
86 hash = hash * 33 + c; /* "perl": k=33, r=r+r/32 */
87 return (hash + (hash >> 5));
88 }
89
90 /*
91 * uint32_t
92 * hash32_strn(const void *buf, size_t len, uint32_t hash)
93 * return a 32 bit hash of NUL terminated ASCII string buf up to
94 * a maximum of len bytes,
95 * seeded with an initial hash value of hash (usually HASH32_STR_INIT).
96 */
97 static __inline uint32_t
98 hash32_strn(const void *buf, size_t len, uint32_t hash)
99 {
100 const uint8_t *s = buf;
101 uint8_t c;
102
103 while ((c = *s++) != 0 && len-- != 0)
104 hash = hash * 33 + c; /* "perl": k=33, r=r+r/32 */
105 return (hash + (hash >> 5));
106 }
107 #endif /* __HAVE_HASH32_STR */
108
109
110 #endif /* !_SYS_HASH_H_ */
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