gearman/libhashkit/fnv_64.cc

/*  vim:expandtab:shiftwidth=2:tabstop=2:smarttab:
 * 
 *  HashKit library
 *
 *  Copyright (C) 2011-2012 Data Differential, http://datadifferential.com/
 *  Copyright (C) 2009 Brian Aker All rights reserved.
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#include <libhashkit/common.h>

#if __WORDSIZE == 64 && defined(HAVE_FNV64_HASH)

/* FNV hash'es lifted from Dustin Sallings work */
static uint64_t FNV_64_INIT= 0xcbf29ce484222325;
static uint64_t FNV_64_PRIME= 0x100000001b3;

uint32_t hashkit_fnv1_64(const char *key, size_t key_length, void *)
{
  /* Thanks to pierre@demartines.com for the pointer */
  uint64_t hash= FNV_64_INIT;

  for (size_t x= 0; x < key_length; x++)
  {
    hash *= FNV_64_PRIME;
    hash ^= (uint64_t)key[x];
  }

  return (uint32_t)hash;
}

uint32_t hashkit_fnv1a_64(const char *key, size_t key_length, void *)
{
  uint32_t hash= (uint32_t) FNV_64_INIT;

  for (size_t x= 0; x < key_length; x++)
  {
    uint32_t val= (uint32_t)key[x];
    hash ^= val;
    hash *= (uint32_t) FNV_64_PRIME;
  }

  return hash;
}

#else
uint32_t hashkit_fnv1_64(const char *, size_t, void *)
{
  return 0;
}

uint32_t hashkit_fnv1a_64(const char *, size_t, void *)
{
  return 0;
}
#endif