git.m6w6.name Git - m6w6/libmemcached/blob - libhashkit/fnv.cc

   1 /* HashKit
   2  * Copyright (C) 2009 Brian Aker
   3  * All rights reserved.
   4  *
   5  * Use and distribution licensed under the BSD license.  See
   6  * the COPYING file in the parent directory for full text.
   7  */
   8
   9 #include <libhashkit/common.h>
  10
  11 /* FNV hash'es lifted from Dustin Sallings work */
  12 static uint64_t FNV_64_INIT= uint64_t(0xcbf29ce484222325);
  13 static uint64_t FNV_64_PRIME= uint64_t(0x100000001b3);
  14 static uint32_t FNV_32_INIT= 2166136261UL;
  15 static uint32_t FNV_32_PRIME= 16777619;
  16
  17 uint32_t hashkit_fnv1_64(const char *key, size_t key_length, void *context)
  18 {
  19   /* Thanks to pierre@demartines.com for the pointer */
  20   uint64_t hash= FNV_64_INIT;
  21   (void)context;
  22
  23   for (size_t x= 0; x < key_length; x++)
  24   {
  25     hash *= FNV_64_PRIME;
  26     hash ^= (uint64_t)key[x];
  27   }
  28
  29   return (uint32_t)hash;
  30 }
  31
  32 uint32_t hashkit_fnv1a_64(const char *key, size_t key_length, void *context)
  33 {
  34   uint32_t hash= (uint32_t) FNV_64_INIT;
  35   (void)context;
  36
  37   for (size_t x= 0; x < key_length; x++)
  38   {
  39     uint32_t val= (uint32_t)key[x];
  40     hash ^= val;
  41     hash *= (uint32_t) FNV_64_PRIME;
  42   }
  43
  44   return hash;
  45 }
  46
  47 uint32_t hashkit_fnv1_32(const char *key, size_t key_length, void *context)
  48 {
  49   uint32_t hash= FNV_32_INIT;
  50   (void)context;
  51
  52   for (size_t x= 0; x < key_length; x++)
  53   {
  54     uint32_t val= (uint32_t)key[x];
  55     hash *= FNV_32_PRIME;
  56     hash ^= val;
  57   }
  58
  59   return hash;
  60 }
  61
  62 uint32_t hashkit_fnv1a_32(const char *key, size_t key_length, void *context)
  63 {
  64   uint32_t hash= FNV_32_INIT;
  65   (void)context;
  66
  67   for (size_t x= 0; x < key_length; x++)
  68   {
  69     uint32_t val= (uint32_t)key[x];
  70     hash ^= val;
  71     hash *= FNV_32_PRIME;
  72   }
  73
  74   return hash;
  75 }