1 files changed, 45 insertions, 0 deletions
diff --git a/sal/rtl/crc.cxx b/sal/rtl/crc.cxx
new file mode 100644
index 000000000..7912b15d0
--- /dev/null
+++ b/sal/rtl/crc.cxx
@@ -0,0 +1,45 @@
+/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
+/*
+ * This file is part of the LibreOffice project.
+ *
+ * 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/.
+ *
+ * This file incorporates work covered by the following license notice:
+ *
+ *   Licensed to the Apache Software Foundation (ASF) under one or more
+ *   contributor license agreements. See the NOTICE file distributed
+ *   with this work for additional information regarding copyright
+ *   ownership. The ASF licenses this file to you under the Apache
+ *   License, Version 2.0 (the "License"); you may not use this file
+ *   except in compliance with the License. You may obtain a copy of
+ *   the License at http://www.apache.org/licenses/LICENSE-2.0 .
+ */
+
+#include <sal/types.h>
+#include <rtl/crc.h>
+#include <cassert>
+
+#include <zlib.h>
+
+// Zlib's crc32() is very fast, so simply use that one instead
+// of implementing this ourselves.
+
+sal_uInt32 SAL_CALL rtl_crc32 (
+    sal_uInt32  Crc,
+    const void *Data, sal_uInt32 DatLen) SAL_THROW_EXTERN_C()
+{
+    // Check that our types map to zlib correctly.
+    static_assert(sizeof(uLong) >= sizeof(sal_uInt32));
+    static_assert(sizeof(uInt) >= sizeof(sal_uInt32));
+    // Our API says that Crc should be initialized to 0, while
+    // zlib says it should be initialized with 'crc32(0,Z_NULL,0)',
+    // which however simply returns 0. Ensure this.
+    assert(crc32(0, Z_NULL, 0) == 0);
+    if (Data)
+        Crc = crc32( Crc, static_cast<const Bytef*>(Data), DatLen);
+    return Crc;
+}
+
+/* vim:set shiftwidth=4 softtabstop=4 expandtab: */