| 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 | #ifndef _SYS_FNV_HASH_H_ |
| 9 | #define _SYS_FNV_HASH_H_ |
| 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 */ |
| 62 | |
| 63 | while ((c = *s++) != 0) { |
| 64 | hval *= FNV_64_PRIME; |
| 65 | hval ^= c; |
| 66 | } |
| 67 | return hval; |
| 68 | } |
| 69 | #endif /* _SYS_FNV_HASH_H_ */ |