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: src/sys/sys/fnv_hash.h,v 1.2.2.1 2001/03/21 10:50:59 peter Exp $
   9  */
  10
  11 #ifndef _SYS_FNV_HASH_H_
  12 #define _SYS_FNV_HASH_H_
  13
  14 #ifndef _SYS_TYPES_H_
  15 #include <sys/types.h>
  16 #endif
  17
  18 typedef u_int32_t Fnv32_t;
  19 typedef u_int64_t Fnv64_t;
  20
  21 #define FNV1_32_INIT ((Fnv32_t) 33554467UL)
  22 #define FNV1_64_INIT ((Fnv64_t) 0xcbf29ce484222325ULL)
  23
  24 #define FNV_32_PRIME ((Fnv32_t) 0x01000193UL)
  25 #define FNV_64_PRIME ((Fnv64_t) 0x100000001b3ULL)
  26
  27 static __inline Fnv32_t
  28 fnv_32_buf(const void *buf, size_t len, Fnv32_t hval)
  29 {
  30         const u_int8_t *s = (const u_int8_t *)buf;
  31
  32         while (len-- != 0) {
  33                 hval *= FNV_32_PRIME;
  34                 hval ^= *s++;
  35         }
  36         return hval;
  37 }
  38
  39 static __inline Fnv32_t
  40 fnv_32_str(const char *str, Fnv32_t hval)
  41 {
  42         const u_int8_t *s = (const u_int8_t *)str;
  43         Fnv32_t c;
  44
  45         while ((c = *s++) != 0) {
  46                 hval *= FNV_32_PRIME;
  47                 hval ^= c;
  48         }
  49         return hval;
  50 }
  51
  52 static __inline Fnv64_t
  53 fnv_64_buf(const void *buf, size_t len, Fnv64_t hval)
  54 {
  55         const u_int8_t *s = (const u_int8_t *)buf;
  56
  57         while (len-- != 0) {
  58                 hval *= FNV_64_PRIME;
  59                 hval ^= *s++;
  60         }
  61         return hval;
  62 }
  63
  64 static __inline Fnv64_t
  65 fnv_64_str(const char *str, Fnv64_t hval)
  66 {
  67         const u_int8_t *s = (const u_int8_t *)str;
  68         u_register_t c;          /* 64 bit on x86_64 */
  69
  70         while ((c = *s++) != 0) {
  71                 hval *= FNV_64_PRIME;
  72                 hval ^= c;
  73         }
  74         return hval;
  75 }
  76
  77 #endif