xref: /freebsd/sys/sys/fnv_hash.h (revision 7afb8adff33d47f10a11368ff54bb2eec5b30165)
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   * $FreeBSD$
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_ */
72