private Int32 FigureCrc32()
        {
            if (_crcCalculated == false)
            {
                Stream input = null;
                // get the original stream:
                if (this._Source == ZipEntrySource.WriteDelegate)
                {
                    var output = new Alienlab.Crc.CrcCalculatorStream(Stream.Null);
                    // allow the application to write the data
                    this._WriteDelegate(this.FileName, output);
                    _Crc32 = output.Crc;
                }
                else if (this._Source == ZipEntrySource.ZipFile)
                {
                    // nothing to do - the CRC is already set
                }
                else
                {
                    if (this._Source == ZipEntrySource.Stream)
                    {
                        PrepSourceStream();
                        input = this._sourceStream;
                    }
                    else if (this._Source == ZipEntrySource.JitStream)
                    {
                        // allow the application to open the stream
                        if (this._sourceStream == null)
                            _sourceStream = this._OpenDelegate(this.FileName);
                        PrepSourceStream();
                        input = this._sourceStream;
                    }
                    else if (this._Source == ZipEntrySource.ZipOutputStream)
                    {
                    }
                    else
                    {
                        //input = File.OpenRead(LocalFileName);
                        input = File.Open(LocalFileName, FileMode.Open, FileAccess.Read, FileShare.ReadWrite);
                    }

                    var crc32 = new Alienlab.Crc.CRC32();
                    _Crc32 = crc32.GetCrc32(input);

                    if (_sourceStream == null)
                    {
#if NETCF
                        input.Close();
#else
                        input.Dispose();
#endif
                    }
                }
                _crcCalculated = true;
            }
            return _Crc32;
        }
        public void Zlib_ParallelDeflateStream()
        {
            var sw = new System.Diagnostics.Stopwatch();
            sw.Start();
            TestContext.WriteLine("{0}: Zlib_ParallelDeflateStream Start", sw.Elapsed);

            int sz = 256*1024 + this.rnd.Next(120000);
            string FileToCompress = System.IO.Path.Combine(TopLevelDir, String.Format("Zlib_ParallelDeflateStream.{0}.txt", sz));

            CreateAndFillFileText( FileToCompress, sz);

            TestContext.WriteLine("{0}: Created file: {1}", sw.Elapsed, FileToCompress );

            byte[] original = File.ReadAllBytes(FileToCompress);

            int crc1 = DoCrc(FileToCompress);

            TestContext.WriteLine("{0}: Original CRC: {1:X8}", sw.Elapsed, crc1 );

            byte[] working = new byte[WORKING_BUFFER_SIZE];
            int n = -1;
            long originalLength;
            MemoryStream ms1 = new MemoryStream();
            {
                using (FileStream fs1 = File.OpenRead(FileToCompress))
                {
                    originalLength = fs1.Length;
                    using (var compressor = new Alienlab.Zlib.ParallelDeflateOutputStream(ms1, true))
                    {
                        while ((n = fs1.Read(working, 0, working.Length)) != 0)
                        {
                            compressor.Write(working, 0, n);
                        }
                    }
                }
                ms1.Seek(0, SeekOrigin.Begin);
            }

            TestContext.WriteLine("{0}: Compressed {1} bytes into {2} bytes", sw.Elapsed,
                                  originalLength, ms1.Length);

            var crc = new Alienlab.Crc.CRC32();
            int crc2= 0;
            byte[] decompressedBytes= null;
            using (MemoryStream ms2 = new MemoryStream())
            {
                using (var decompressor = new DeflateStream(ms1, CompressionMode.Decompress, false))
                {
                    while ((n = decompressor.Read(working, 0, working.Length)) != 0)
                    {
                        ms2.Write(working, 0, n);
                    }
                }
                TestContext.WriteLine("{0}: Decompressed", sw.Elapsed);
                TestContext.WriteLine("{0}: Decompressed length: {1}", sw.Elapsed, ms2.Length);
                ms2.Seek(0, SeekOrigin.Begin);
                crc2 = crc.GetCrc32(ms2);
                decompressedBytes = ms2.ToArray();
                TestContext.WriteLine("{0}: Decompressed CRC: {1:X8}", sw.Elapsed, crc2 );
            }


            TestContext.WriteLine("{0}: Checking...", sw.Elapsed );

            bool check = true;
            if (originalLength != decompressedBytes.Length)
            {
                TestContext.WriteLine("Different lengths.");
                check = false;
            }
            else
            {
                for (int i = 0; i < decompressedBytes.Length; i++)
                {
                    if (original[i] != decompressedBytes[i])
                    {
                        TestContext.WriteLine("byte {0} differs", i);
                        check = false;
                        break;
                    }
                }
            }

            Assert.IsTrue(check,"Data check failed");
            TestContext.WriteLine("{0}: Done...", sw.Elapsed );
        }