public void TestDecompressionOfStreamCompression()
{
MemoryStream memStream = new MemoryStream();
Random rnd = new Random();
byte[] original;
byte[] decompressed;
int decompressedLen;
bool match;
PatternCompressor compressor = new PatternCompressor
{
CompressedBuffer = new byte[4 * TotalTestSampleSize],
CompressionStrength = 31
};
for (int i = 0; i < TotalTestSampleSize; i++)
{
uint value = (uint)(rnd.NextDouble() * 100000);
memStream.Write(BitConverter.GetBytes(value), 0, 4);
compressor.Compress(value);
}
original = memStream.ToArray();
decompressed = new byte[PatternDecompressor.MaximumSizeDecompressed(compressor.CompressedBufferLength)];
Buffer.BlockCopy(compressor.CompressedBuffer, 0, decompressed, 0, compressor.CompressedBufferLength);
decompressedLen = PatternDecompressor.DecompressBuffer(decompressed, 0, compressor.CompressedBufferLength, decompressed.Length);
match = decompressedLen == original.Length;
for (int i = 0; match && i < decompressedLen; i++)
{
match = decompressed[i] == original[i];
}
Assert.AreEqual(original.Length, decompressedLen);
Assert.IsTrue(match);
}
/// <summary>
/// Decompresses <see cref="CompactMeasurement"/> values from the given <paramref name="source"/> buffer.
/// </summary>
/// <param name="source">Buffer with compressed <see cref="CompactMeasurement"/> payload.</param>
/// <param name="signalIndexCache">Current <see cref="SignalIndexCache"/>.</param>
/// <param name="index">Index into buffer where compressed payload begins.</param>
/// <param name="dataLength">Length of all data within <paramref name="source"/> buffer.</param>
/// <param name="measurementCount">Number of compressed measurements in the payload.</param>
/// <param name="includeTime">Flag that determines if timestamps as included in the payload.</param>
/// <param name="flags">Current <see cref="DataPacketFlags"/>.</param>
/// <returns>Decompressed <see cref="CompactMeasurement"/> values from the given <paramref name="source"/> buffer.</returns>
public static CompactMeasurement[] DecompressPayload(this byte[] source, SignalIndexCache signalIndexCache, int index, int dataLength, int measurementCount, bool includeTime, DataPacketFlags flags)
{
CompactMeasurement[] measurements = new CompactMeasurement[measurementCount];
// Actual data length has to take into account response byte and in-response-to server command byte in the payload header
//int dataLength = length - index - 2;
int bufferLength = PatternDecompressor.MaximumSizeDecompressed(dataLength);
// Copy source data into a decompression buffer
byte[] buffer = new byte[bufferLength];
Buffer.BlockCopy(source, index, buffer, 0, dataLength);
// Check that OS endian-order matches endian-order of compressed data
if (!(BitConverter.IsLittleEndian && (flags & DataPacketFlags.LittleEndianCompression) > 0))
{
// can be modified to decompress a payload that is in a non-native Endian order
throw new NotImplementedException("Cannot currently decompress payload that is not in native endian-order.");
}
// Attempt to decompress buffer
int uncompressedSize = PatternDecompressor.DecompressBuffer(buffer, 0, dataLength, bufferLength);
if (uncompressedSize == 0)
{
throw new InvalidOperationException("Failed to decompress payload buffer - possible data corruption.");
}
index = 0;
// Decode ID and state flags
for (int i = 0; i < measurementCount; i++)
{
uint value = NativeEndianOrder.Default.ToUInt32(buffer, index);
measurements[i] = new CompactMeasurement(signalIndexCache, includeTime)
{
CompactStateFlags = (byte)(value >> 16),
RuntimeID = (ushort)value
};
index += 4;
}
// Decode values
for (int i = 0; i < measurementCount; i++)
{
measurements[i].Value = NativeEndianOrder.Default.ToSingle(buffer, index);
index += 4;
}
if (includeTime)
{
// Decode timestamps
for (int i = 0; i < measurementCount; i++)
{
measurements[i].Timestamp = NativeEndianOrder.Default.ToInt64(buffer, index);
index += 8;
}
}
return(measurements);
}
public void TestArrayOfIntCompressionOnRandomData()
{
StringBuilder results = new StringBuilder();
MemoryStream buffer = new MemoryStream();
Random rnd = new Random();
uint value;
for (int i = 0; i < TotalTestSampleSize; i++)
{
value = (uint)(rnd.NextDouble() * 100000);
buffer.Write(BitConverter.GetBytes(value), 0, 4);
}
// Add one byte of extra space to accommodate compression algorithm
buffer.WriteByte(0xFF);
byte[] arrayOfInts = buffer.ToArray();
byte[] copy = arrayOfInts.BlockCopy(0, arrayOfInts.Length);
int bufferLen = arrayOfInts.Length;
int dataLen = bufferLen - 1;
int gzipLen = arrayOfInts.Compress().Length;
int compressedLen, decompressedLen, maxDecompressedLen;
Ticks compressTime, decompressTime;
Ticks stopTime, startTime;
bool lossless;
// Make sure a buffer exists in the buffer pool so that operation time will not be skewed by buffer initialization:
startTime = DateTime.UtcNow.Ticks;
BufferPool.ReturnBuffer(BufferPool.TakeBuffer(dataLen + TotalTestSampleSize));
stopTime = DateTime.UtcNow.Ticks;
results.AppendFormat("Buffer Pool initial take time: {0}\r\n", (stopTime - startTime).ToElapsedTimeString(4));
startTime = DateTime.UtcNow.Ticks;
BufferPool.ReturnBuffer(BufferPool.TakeBuffer(dataLen + TotalTestSampleSize));
stopTime = DateTime.UtcNow.Ticks;
results.AppendFormat("Buffer Pool cached take time: {0}\r\n\r\n", (stopTime - startTime).ToElapsedTimeString(4));
startTime = DateTime.UtcNow.Ticks;
compressedLen = PatternCompressor.CompressBuffer(arrayOfInts, 0, dataLen, bufferLen, 31);
stopTime = DateTime.UtcNow.Ticks;
compressTime = stopTime - startTime;
maxDecompressedLen = PatternDecompressor.MaximumSizeDecompressed(compressedLen);
if (arrayOfInts.Length < maxDecompressedLen)
{
byte[] temp = new byte[maxDecompressedLen];
Buffer.BlockCopy(arrayOfInts, 0, temp, 0, compressedLen);
arrayOfInts = temp;
}
startTime = DateTime.UtcNow.Ticks;
decompressedLen = PatternDecompressor.DecompressBuffer(arrayOfInts, 0, compressedLen, maxDecompressedLen);
stopTime = DateTime.UtcNow.Ticks;
decompressTime = stopTime - startTime;
lossless = decompressedLen == dataLen;
for (int i = 0; lossless && i < Math.Min(decompressedLen, dataLen); i++)
{
lossless = arrayOfInts[i] == copy[i];
}
// Publish results to debug window
results.AppendFormat("Results of floating point compression algorithm over sequential data:\r\n\r\n");
results.AppendFormat("Total number of samples: \t{0:#,##0}\r\n", TotalTestSampleSize);
results.AppendFormat("Total number of bytes: \t{0:#,##0}\r\n", dataLen);
results.AppendFormat("Total compression time: \t{0}\r\n", compressTime.ToElapsedTimeString(4));
results.AppendFormat("Compression speed: \t{0:#,##0.0000} MB/sec\r\n", (dataLen / (double)SI2.Mega) / compressTime.ToSeconds());
results.AppendFormat("Total decompression time: \t{0}\r\n", decompressTime.ToElapsedTimeString(4));
results.AppendFormat("Decompression speed: \t{0:#,##0.0000} MB/sec\r\n", (dataLen / (double)SI2.Mega) / decompressTime.ToSeconds());
results.AppendFormat("Compression results: \t{0:0.00%}\r\n", (dataLen - compressedLen) / (double)dataLen);
results.AppendFormat("Standard gzip results: \t{0:0.00%}\r\n", (dataLen - gzipLen) / (double)dataLen);
Debug.WriteLine(results.ToString());
Assert.AreEqual(dataLen, decompressedLen);
Assert.IsTrue(lossless);
}