firmware/lib/utility.c


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/* Copyright (c) 2011 The Chromium OS Authors. All rights reserved.
 * Use of this source code is governed by a BSD-style license that can be
 * found in the LICENSE file.
 *
 * Utility functions that need to be built as part of the firmware.
 */

#include "sysincludes.h"
#include "utility.h"

int SafeMemcmp(const void* s1, const void* s2, size_t n) {
  const unsigned char* us1 = s1;
  const unsigned char* us2 = s2;
  int result = 0;

  if (0 == n)
    return 0;

  /* Code snippet without data-dependent branch due to
   * Nate Lawson (nate@root.org) of Root Labs. */
  while (n--)
    result |= *us1++ ^ *us2++;

  return result != 0;
}