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

   1 /*  vim:expandtab:shiftwidth=2:tabstop=2:smarttab:
   2  *
   3  *  HashKit library
   4  *
   5  *  Copyright (C) 2011 Data Differential, http://datadifferential.com/
   6  *  Copyright (C) 2009 Brian Aker All rights reserved.
   7  *
   8  *  Redistribution and use in source and binary forms, with or without
   9  *  modification, are permitted provided that the following conditions are
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  11  *
  12  *      * Redistributions of source code must retain the above copyright
  13  *  notice, this list of conditions and the following disclaimer.
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  15  *      * Redistributions in binary form must reproduce the above
  16  *  copyright notice, this list of conditions and the following disclaimer
  17  *  in the documentation and/or other materials provided with the
  18  *  distribution.
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  20  *      * The names of its contributors may not be used to endorse or
  21  *  promote products derived from this software without specific prior
  22  *  written permission.
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  24  *  THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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  37
  38
  39 #include <libhashkit/common.h>
  40
  41 /* FNV hash'es lifted from Dustin Sallings work */
  42 static uint64_t FNV_64_INIT= 0xcbf29ce484222325;
  43 static uint64_t FNV_64_PRIME= 0x100000001b3;
  44
  45 uint32_t hashkit_fnv1_64(const char *key, size_t key_length, void *)
  46 {
  47   /* Thanks to pierre@demartines.com for the pointer */
  48   uint64_t hash= FNV_64_INIT;
  49
  50   for (size_t x= 0; x < key_length; x++)
  51   {
  52     hash *= FNV_64_PRIME;
  53     hash ^= (uint64_t)key[x];
  54   }
  55
  56   return (uint32_t)hash;
  57 }
  58
  59 uint32_t hashkit_fnv1a_64(const char *key, size_t key_length, void *)
  60 {
  61   uint32_t hash= (uint32_t) FNV_64_INIT;
  62
  63   for (size_t x= 0; x < key_length; x++)
  64   {
  65     uint32_t val= (uint32_t)key[x];
  66     hash ^= val;
  67     hash *= (uint32_t) FNV_64_PRIME;
  68   }
  69
  70   return hash;
  71 }