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 1.2 2003/06/17 04:28:58 dillon Exp $ 10 */ 11 12 typedef u_int32_t Fnv32_t; 13 typedef u_int64_t Fnv64_t; 14 15 #define FNV1_32_INIT ((Fnv32_t) 33554467UL) 16 #define FNV1_64_INIT ((Fnv64_t) 0xcbf29ce484222325ULL) 17 18 #define FNV_32_PRIME ((Fnv32_t) 0x01000193UL) 19 #define FNV_64_PRIME ((Fnv64_t) 0x100000001b3ULL) 20 21 static __inline Fnv32_t 22 fnv_32_buf(const void *buf, size_t len, Fnv32_t hval) 23 { 24 const u_int8_t *s = (const u_int8_t *)buf; 25 26 while (len-- != 0) { 27 hval *= FNV_32_PRIME; 28 hval ^= *s++; 29 } 30 return hval; 31 } 32 33 static __inline Fnv32_t 34 fnv_32_str(const char *str, Fnv32_t hval) 35 { 36 const u_int8_t *s = (const u_int8_t *)str; 37 Fnv32_t c; 38 39 while ((c = *s++) != 0) { 40 hval *= FNV_32_PRIME; 41 hval ^= c; 42 } 43 return hval; 44 } 45 46 static __inline Fnv64_t 47 fnv_64_buf(const void *buf, size_t len, Fnv64_t hval) 48 { 49 const u_int8_t *s = (const u_int8_t *)buf; 50 51 while (len-- != 0) { 52 hval *= FNV_64_PRIME; 53 hval ^= *s++; 54 } 55 return hval; 56 } 57 58 static __inline Fnv64_t 59 fnv_64_str(const char *str, Fnv64_t hval) 60 { 61 const u_int8_t *s = (const u_int8_t *)str; 62 u_register_t c; /* 32 bit on i386, 64 bit on alpha,ia64 */ 63 64 while ((c = *s++) != 0) { 65 hval *= FNV_64_PRIME; 66 hval ^= c; 67 } 68 return hval; 69 } 70