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: releng/8.0/sys/sys/fnv_hash.h 139825 2005-01-07 02:29:27Z imp $
9 */
10
11 typedef u_int32_t Fnv32_t;
12 typedef u_int64_t Fnv64_t;
13
14 #define FNV1_32_INIT ((Fnv32_t) 33554467UL)
15 #define FNV1_64_INIT ((Fnv64_t) 0xcbf29ce484222325ULL)
16
17 #define FNV_32_PRIME ((Fnv32_t) 0x01000193UL)
18 #define FNV_64_PRIME ((Fnv64_t) 0x100000001b3ULL)
19
20 static __inline Fnv32_t
21 fnv_32_buf(const void *buf, size_t len, Fnv32_t hval)
22 {
23 const u_int8_t *s = (const u_int8_t *)buf;
24
25 while (len-- != 0) {
26 hval *= FNV_32_PRIME;
27 hval ^= *s++;
28 }
29 return hval;
30 }
31
32 static __inline Fnv32_t
33 fnv_32_str(const char *str, Fnv32_t hval)
34 {
35 const u_int8_t *s = (const u_int8_t *)str;
36 Fnv32_t c;
37
38 while ((c = *s++) != 0) {
39 hval *= FNV_32_PRIME;
40 hval ^= c;
41 }
42 return hval;
43 }
44
45 static __inline Fnv64_t
46 fnv_64_buf(const void *buf, size_t len, Fnv64_t hval)
47 {
48 const u_int8_t *s = (const u_int8_t *)buf;
49
50 while (len-- != 0) {
51 hval *= FNV_64_PRIME;
52 hval ^= *s++;
53 }
54 return hval;
55 }
56
57 static __inline Fnv64_t
58 fnv_64_str(const char *str, Fnv64_t hval)
59 {
60 const u_int8_t *s = (const u_int8_t *)str;
61 u_register_t c; /* 32 bit on i386, 64 bit on alpha,ia64 */
62
63 while ((c = *s++) != 0) {
64 hval *= FNV_64_PRIME;
65 hval ^= c;
66 }
67 return hval;
68 }
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