FreeBSD/Linux Kernel Cross Reference
sys/sys/fnv_hash.h
1 /*
2 * Fowler / Noll / Vo Hash (FNV Hash)
3 * http://www.isthe.com/chongo/tech/comp/fnv/
4 *
5 * This is an implementation of the algorithms posted above.
6 * This file is placed in the public domain by Peter Wemm.
7 *
8 * $FreeBSD: src/sys/sys/fnv_hash.h,v 1.2.2.1 2001/03/21 10:50:59 peter Exp $
9 * $DragonFly: src/sys/sys/fnv_hash.h,v 1.3 2006/05/20 02:42:13 dillon Exp $
10 */
11
12 #ifndef _SYS_FNV_HASH_H_
13 #define _SYS_FNV_HASH_H_
14
15 #ifndef _SYS_TYPES_H_
16 #include <sys/types.h>
17 #endif
18
19 typedef u_int32_t Fnv32_t;
20 typedef u_int64_t Fnv64_t;
21
22 #define FNV1_32_INIT ((Fnv32_t) 33554467UL)
23 #define FNV1_64_INIT ((Fnv64_t) 0xcbf29ce484222325ULL)
24
25 #define FNV_32_PRIME ((Fnv32_t) 0x01000193UL)
26 #define FNV_64_PRIME ((Fnv64_t) 0x100000001b3ULL)
27
28 static __inline Fnv32_t
29 fnv_32_buf(const void *buf, size_t len, Fnv32_t hval)
30 {
31 const u_int8_t *s = (const u_int8_t *)buf;
32
33 while (len-- != 0) {
34 hval *= FNV_32_PRIME;
35 hval ^= *s++;
36 }
37 return hval;
38 }
39
40 static __inline Fnv32_t
41 fnv_32_str(const char *str, Fnv32_t hval)
42 {
43 const u_int8_t *s = (const u_int8_t *)str;
44 Fnv32_t c;
45
46 while ((c = *s++) != 0) {
47 hval *= FNV_32_PRIME;
48 hval ^= c;
49 }
50 return hval;
51 }
52
53 static __inline Fnv64_t
54 fnv_64_buf(const void *buf, size_t len, Fnv64_t hval)
55 {
56 const u_int8_t *s = (const u_int8_t *)buf;
57
58 while (len-- != 0) {
59 hval *= FNV_64_PRIME;
60 hval ^= *s++;
61 }
62 return hval;
63 }
64
65 static __inline Fnv64_t
66 fnv_64_str(const char *str, Fnv64_t hval)
67 {
68 const u_int8_t *s = (const u_int8_t *)str;
69 u_register_t c; /* 32 bit on i386, 64 bit on alpha,ia64 */
70
71 while ((c = *s++) != 0) {
72 hval *= FNV_64_PRIME;
73 hval ^= c;
74 }
75 return hval;
76 }
77
78 #endif
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