public void Zlib_Codec_TestLargeDeflateInflate()
{
int rc;
int j;
int bufferSize = 80000;
byte[] compressedBytes = new byte[bufferSize];
byte[] workBuffer = new byte[bufferSize / 4];
ZlibCodec compressingStream = new ZlibCodec();
rc = compressingStream.InitializeDeflate(CompressionLevel.Level1);
Assert.AreEqual<int>(ZlibConstants.Z_OK, rc, String.Format("at InitializeDeflate() [{0}]", compressingStream.Message));
compressingStream.OutputBuffer = compressedBytes;
compressingStream.AvailableBytesOut = compressedBytes.Length;
compressingStream.NextOut = 0;
System.Random rnd = new Random();
for (int k = 0; k < 4; k++)
{
switch (k)
{
case 0:
// At this point, workBuffer is all zeroes, so it should compress very well.
break;
case 1:
// switch to no compression, keep same workBuffer (all zeroes):
compressingStream.SetDeflateParams(CompressionLevel.None, CompressionStrategy.Default);
break;
case 2:
// Insert data into workBuffer, and switch back to compressing mode.
// we'll use lengths of the same random byte:
for (int i = 0; i < workBuffer.Length / 1000; i++)
{
byte b = (byte)rnd.Next();
int n = 500 + rnd.Next(500);
for (j = 0; j < n; j++)
workBuffer[j + i] = b;
i += j - 1;
}
compressingStream.SetDeflateParams(CompressionLevel.BestCompression, CompressionStrategy.Filtered);
break;
case 3:
// insert totally random data into the workBuffer
rnd.NextBytes(workBuffer);
break;
}
compressingStream.InputBuffer = workBuffer;
compressingStream.NextIn = 0;
compressingStream.AvailableBytesIn = workBuffer.Length;
rc = compressingStream.Deflate(FlushType.None);
Assert.AreEqual<int>(ZlibConstants.Z_OK, rc, String.Format("at Deflate({0}) [{1}]", k, compressingStream.Message));
if (k == 0)
Assert.AreEqual<int>(0, compressingStream.AvailableBytesIn, "Deflate should be greedy.");
TestContext.WriteLine("Stage {0}: uncompressed/compresssed bytes so far: ({1,6}/{2,6})",
k, compressingStream.TotalBytesIn, compressingStream.TotalBytesOut);
}
rc = compressingStream.Deflate(FlushType.Finish);
Assert.AreEqual<int>(ZlibConstants.Z_STREAM_END, rc, String.Format("at Deflate() [{0}]", compressingStream.Message));
rc = compressingStream.EndDeflate();
Assert.AreEqual<int>(ZlibConstants.Z_OK, rc, String.Format("at EndDeflate() [{0}]", compressingStream.Message));
TestContext.WriteLine("Final: uncompressed/compressed bytes: ({0,6},{1,6})",
compressingStream.TotalBytesIn, compressingStream.TotalBytesOut);
ZlibCodec decompressingStream = new ZlibCodec(CompressionMode.Decompress);
decompressingStream.InputBuffer = compressedBytes;
decompressingStream.NextIn = 0;
decompressingStream.AvailableBytesIn = bufferSize;
// upon inflating, we overwrite the decompressedBytes buffer repeatedly
int nCycles = 0;
while (true)
{
decompressingStream.OutputBuffer = workBuffer;
decompressingStream.NextOut = 0;
decompressingStream.AvailableBytesOut = workBuffer.Length;
rc = decompressingStream.Inflate(FlushType.None);
nCycles++;
if (rc == ZlibConstants.Z_STREAM_END)
break;
Assert.AreEqual<int>(ZlibConstants.Z_OK, rc, String.Format("at Inflate() [{0}] TotalBytesOut={1}",
decompressingStream.Message, decompressingStream.TotalBytesOut));
}
rc = decompressingStream.EndInflate();
Assert.AreEqual<int>(ZlibConstants.Z_OK, rc, String.Format("at EndInflate() [{0}]", decompressingStream.Message));
Assert.AreEqual<int>(4 * workBuffer.Length, (int)decompressingStream.TotalBytesOut);
TestContext.WriteLine("compressed length: {0}", compressingStream.TotalBytesOut);
TestContext.WriteLine("decompressed length (expected): {0}", 4 * workBuffer.Length);
TestContext.WriteLine("decompressed length (actual) : {0}", decompressingStream.TotalBytesOut);
TestContext.WriteLine("decompression cycles: {0}", nCycles);
}
