private Int32 FigureCrc32()
{
if (_crcCalculated == false)
{
Stream input = null;
// get the original stream:
if (_sourceStream != null)
{
_sourceStream.Position = 0;
input = _sourceStream;
}
else
{
input = System.IO.File.OpenRead(LocalFileName);
}
var crc32 = new CRC32();
_Crc32 = crc32.GetCrc32(input);
if (_sourceStream == null)
{
input.Close();
input.Dispose();
}
_crcCalculated = true;
}
return _Crc32;
}
