mfbt/HashFunctions.cpp

   1 /* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
   2 /* This Source Code Form is subject to the terms of the Mozilla Public
   3  * License, v. 2.0. If a copy of the MPL was not distributed with this
   4  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
   5
   6 /* Implementations of hash functions. */
   7
   8 #include "mozilla/HashFunctions.h"
   9 #include "mozilla/Types.h"
  10
  11 #include <string.h>
  12
  13 namespace mozilla {
  14
  15 uint32_t
  16 HashBytes(const void* bytes, size_t length)
  17 {
  18   uint32_t hash = 0;
  19   const char* b = reinterpret_cast<const char*>(bytes);
  20
  21   /* Walk word by word. */
  22   size_t i = 0;
  23   for (; i < length - (length % sizeof(size_t)); i += sizeof(size_t)) {
  24     /* Do an explicitly unaligned load of the data. */
  25     size_t data;
  26     memcpy(&data, b + i, sizeof(size_t));
  27
  28     hash = AddToHash(hash, data, sizeof(data));
  29   }
  30
  31   /* Get the remaining bytes. */
  32   for (; i < length; i++)
  33     hash = AddToHash(hash, b[i]);
  34
  35   return hash;
  36 }
  37
  38 } /* namespace mozilla */