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/12.0/sys/sys/fnv_hash.h 268351 2014-07-07 00:27:09Z marcel $
9 */
10 #ifndef _SYS_FNV_HASH_H_
11 #define _SYS_FNV_HASH_H_
12
13 typedef u_int32_t Fnv32_t;
14 typedef u_int64_t Fnv64_t;
15
16 #define FNV1_32_INIT ((Fnv32_t) 33554467UL)
17 #define FNV1_64_INIT ((Fnv64_t) 0xcbf29ce484222325ULL)
18
19 #define FNV_32_PRIME ((Fnv32_t) 0x01000193UL)
20 #define FNV_64_PRIME ((Fnv64_t) 0x100000001b3ULL)
21
22 static __inline Fnv32_t
23 fnv_32_buf(const void *buf, size_t len, Fnv32_t hval)
24 {
25 const u_int8_t *s = (const u_int8_t *)buf;
26
27 while (len-- != 0) {
28 hval *= FNV_32_PRIME;
29 hval ^= *s++;
30 }
31 return hval;
32 }
33
34 static __inline Fnv32_t
35 fnv_32_str(const char *str, Fnv32_t hval)
36 {
37 const u_int8_t *s = (const u_int8_t *)str;
38 Fnv32_t c;
39
40 while ((c = *s++) != 0) {
41 hval *= FNV_32_PRIME;
42 hval ^= c;
43 }
44 return hval;
45 }
46
47 static __inline Fnv64_t
48 fnv_64_buf(const void *buf, size_t len, Fnv64_t hval)
49 {
50 const u_int8_t *s = (const u_int8_t *)buf;
51
52 while (len-- != 0) {
53 hval *= FNV_64_PRIME;
54 hval ^= *s++;
55 }
56 return hval;
57 }
58
59 static __inline Fnv64_t
60 fnv_64_str(const char *str, Fnv64_t hval)
61 {
62 const u_int8_t *s = (const u_int8_t *)str;
63 u_register_t c; /* 32 bit on i386, 64 bit on alpha */
64
65 while ((c = *s++) != 0) {
66 hval *= FNV_64_PRIME;
67 hval ^= c;
68 }
69 return hval;
70 }
71 #endif /* _SYS_FNV_HASH_H_ */
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