sal/rtl/crc.cxx

   1 /* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
   2 /*
   3  * This file is part of the LibreOffice project.
   4  *
   5  * This Source Code Form is subject to the terms of the Mozilla Public
   6  * License, v. 2.0. If a copy of the MPL was not distributed with this
   7  * file, You can obtain one at http://mozilla.org/MPL/2.0/.
   8  *
   9  * This file incorporates work covered by the following license notice:
  10  *
  11  *   Licensed to the Apache Software Foundation (ASF) under one or more
  12  *   contributor license agreements. See the NOTICE file distributed
  13  *   with this work for additional information regarding copyright
  14  *   ownership. The ASF licenses this file to you under the Apache
  15  *   License, Version 2.0 (the "License"); you may not use this file
  16  *   except in compliance with the License. You may obtain a copy of
  17  *   the License at http://www.apache.org/licenses/LICENSE-2.0 .
  18  */
  19
  20 #include <sal/types.h>
  21 #include <rtl/crc.h>
  22 #include <cassert>
  23
  24 #include <zlib.h>
  25
  26 // Zlib's crc32() is very fast, so simply use that one instead
  27 // of implementing this ourselves.
  28
  29 sal_uInt32 SAL_CALL rtl_crc32 (
  30     sal_uInt32  Crc,
  31     const void *Data, sal_uInt32 DatLen) SAL_THROW_EXTERN_C()
  32 {
  33     // Check that our types map to zlib correctly.
  34     static_assert(sizeof(uLong) >= sizeof(sal_uInt32));
  35     static_assert(sizeof(uInt) >= sizeof(sal_uInt32));
  36     // Our API says that Crc should be initialized to 0, while
  37     // zlib says it should be initialized with 'crc32(0,Z_NULL,0)',
  38     // which however simply returns 0. Ensure this.
  39     assert(crc32(0, Z_NULL, 0) == 0);
  40     if (Data)
  41         Crc = crc32( Crc, static_cast<const Bytef*>(Data), DatLen);
  42     return Crc;
  43 }
  44
  45 /* vim:set shiftwidth=4 softtabstop=4 expandtab: */