import FIREFOX_52_6_0esr_RELEASE from mozilla-esr52 hg repo

mfbt/HashFunctions.cpp

@@ -0,0 +1,39 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+/* Implementations of hash functions. */
+
+#include "mozilla/HashFunctions.h"
+#include "mozilla/Types.h"
+
+#include <string.h>
+
+namespace mozilla {
+
+uint32_t
+HashBytes(const void* aBytes, size_t aLength)
+{
+  uint32_t hash = 0;
+  const char* b = reinterpret_cast<const char*>(aBytes);
+
+  /* Walk word by word. */
+  size_t i = 0;
+  for (; i < aLength - (aLength % sizeof(size_t)); i += sizeof(size_t)) {
+    /* Do an explicitly unaligned load of the data. */
+    size_t data;
+    memcpy(&data, b + i, sizeof(size_t));
+
+    hash = AddToHash(hash, data, sizeof(data));
+  }
+
+  /* Get the remaining bytes. */
+  for (; i < aLength; i++) {
+    hash = AddToHash(hash, b[i]);
+  }
+  return hash;
+}
+
+} /* namespace mozilla */