mfbt/HashFunctions.cpp

   1 /* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
   2 /* vim: set ts=8 sts=2 et sw=2 tw=80: */
   3 /* This Source Code Form is subject to the terms of the Mozilla Public
   4  * License, v. 2.0. If a copy of the MPL was not distributed with this
   5  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
   6
   7 /* Implementations of hash functions. */
   8
   9 #include "mozilla/HashFunctions.h"
  10 #include "mozilla/Types.h"
  11
  12 #include <string.h>
  13
  14 namespace mozilla {
  15
  16 uint32_t
  17 HashBytes(const void* aBytes, size_t aLength)
  18 {
  19   uint32_t hash = 0;
  20   const char* b = reinterpret_cast<const char*>(aBytes);
  21
  22   /* Walk word by word. */
  23   size_t i = 0;
  24   for (; i < aLength - (aLength % sizeof(size_t)); i += sizeof(size_t)) {
  25     /* Do an explicitly unaligned load of the data. */
  26     size_t data;
  27     memcpy(&data, b + i, sizeof(size_t));
  28
  29     hash = AddToHash(hash, data, sizeof(data));
  30   }
  31
  32   /* Get the remaining bytes. */
  33   for (; i < aLength; i++) {
  34     hash = AddToHash(hash, b[i]);
  35   }
  36   return hash;
  37 }
  38
  39 } /* namespace mozilla */