git.m6w6.name Git - awesomized/libmemcached/blob - src/libhashkit/fnv_64.cc

   1 /*
   2     +--------------------------------------------------------------------+
   3     | libmemcached-awesome - C/C++ Client Library for memcached          |
   4     +--------------------------------------------------------------------+
   5     | Redistribution and use in source and binary forms, with or without |
   6     | modification, are permitted under the terms of the BSD license.    |
   7     | You should have received a copy of the license in a bundled file   |
   8     | named LICENSE; in case you did not receive a copy you can review   |
   9     | the terms online at: https://opensource.org/licenses/BSD-3-Clause  |
  10     +--------------------------------------------------------------------+
  11     | Copyright (c) 2006-2014 Brian Aker   https://datadifferential.com/ |
  12     | Copyright (c) 2020-2021 Michael Wallner        https://awesome.co/ |
  13     +--------------------------------------------------------------------+
  14 */
  15
  16 #include "libhashkit/common.h"
  17
  18 #if __WORDSIZE == 64 && defined(HAVE_FNV64_HASH)
  19
  20 /* FNV hash'es lifted from Dustin Sallings work */
  21 static uint64_t FNV_64_INIT = 0xcbf29ce484222325;
  22 static uint64_t FNV_64_PRIME = 0x100000001b3;
  23
  24 uint32_t hashkit_fnv1_64(const char *key, size_t key_length, void *) {
  25   /* Thanks to pierre@demartines.com for the pointer */
  26   uint64_t hash = FNV_64_INIT;
  27
  28   for (size_t x = 0; x < key_length; x++) {
  29     hash *= FNV_64_PRIME;
  30     hash ^= (uint64_t) key[x];
  31   }
  32
  33   return (uint32_t) hash;
  34 }
  35
  36 uint32_t hashkit_fnv1a_64(const char *key, size_t key_length, void *) {
  37   uint32_t hash = (uint32_t) FNV_64_INIT;
  38
  39   for (size_t x = 0; x < key_length; x++) {
  40     uint32_t val = (uint32_t) key[x];
  41     hash ^= val;
  42     hash *= (uint32_t) FNV_64_PRIME;
  43   }
  44
  45   return hash;
  46 }
  47
  48 #else
  49 uint32_t hashkit_fnv1_64(const char *, size_t, void *) {
  50   return 0;
  51 }
  52
  53 uint32_t hashkit_fnv1a_64(const char *, size_t, void *) {
  54   return 0;
  55 }
  56 #endif