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  * $DragonFly: src/sys/sys/fnv_hash.h,v 1.3 2006/05/20 02:42:13 dillon Exp $
  10  */
  11
  12 #ifndef _SYS_FNV_HASH_H_
  13 #define _SYS_FNV_HASH_H_
  14
  15 #ifndef _SYS_TYPES_H_
  16 #include <sys/types.h>
  17 #endif
  18
  19 typedef u_int32_t Fnv32_t;
  20 typedef u_int64_t Fnv64_t;
  21
  22 #define FNV1_32_INIT ((Fnv32_t) 33554467UL)
  23 #define FNV1_64_INIT ((Fnv64_t) 0xcbf29ce484222325ULL)
  24
  25 #define FNV_32_PRIME ((Fnv32_t) 0x01000193UL)
  26 #define FNV_64_PRIME ((Fnv64_t) 0x100000001b3ULL)
  27
  28 static __inline Fnv32_t
  29 fnv_32_buf(const void *buf, size_t len, Fnv32_t hval)
  30 {
  31         const u_int8_t *s = (const u_int8_t *)buf;
  32
  33         while (len-- != 0) {
  34                 hval *= FNV_32_PRIME;
  35                 hval ^= *s++;
  36         }
  37         return hval;
  38 }
  39
  40 static __inline Fnv32_t
  41 fnv_32_str(const char *str, Fnv32_t hval)
  42 {
  43         const u_int8_t *s = (const u_int8_t *)str;
  44         Fnv32_t c;
  45
  46         while ((c = *s++) != 0) {
  47                 hval *= FNV_32_PRIME;
  48                 hval ^= c;
  49         }
  50         return hval;
  51 }
  52
  53 static __inline Fnv64_t
  54 fnv_64_buf(const void *buf, size_t len, Fnv64_t hval)
  55 {
  56         const u_int8_t *s = (const u_int8_t *)buf;
  57
  58         while (len-- != 0) {
  59                 hval *= FNV_64_PRIME;
  60                 hval ^= *s++;
  61         }
  62         return hval;
  63 }
  64
  65 static __inline Fnv64_t
  66 fnv_64_str(const char *str, Fnv64_t hval)
  67 {
  68         const u_int8_t *s = (const u_int8_t *)str;
  69         u_register_t c;          /* 32 bit on i386, 64 bit on alpha,ia64 */
  70
  71         while ((c = *s++) != 0) {
  72                 hval *= FNV_64_PRIME;
  73                 hval ^= c;
  74         }
  75         return hval;
  76 }
  77
  78 #endif