/// <summary>
/// Compresses int[] packet data, returns it as a byte[]
/// </summary>
/// <param name="input">assumed to be point data (x,x,x,x,x,x,x)</param>
/// <param name="compression">magic byte specifying the compression to use</param>
/// <returns></returns>
internal byte[] CompressPacketData(int[] input, byte compression)
{
if (input == null)
{
throw new ArgumentNullException("input");
}
List <byte> compressedData = new List <byte>();
//leave room at the beginning of
//compressedData for the compression header byte
//which we will add at the end
compressedData.Add((byte)0);
if (DefaultCompression == (DefaultCompression & compression))
{
compression = GetBestDefHuff(input);
}
if (IndexedHuffman == (DefaultCompression & compression))
{
DataXform dtxf = this.HuffModule.FindDtXf(compression);
HuffCodec huffCodec = this.HuffModule.FindCodec(compression);
huffCodec.Compress(dtxf, input, compressedData);
if (((compressedData.Count - 1 /*for the algo byte we just made room for*/) >> 2) > input.Length)
{
//recompress with no compression (gorilla)
compression = NoCompression;
//reset
compressedData.Clear();
compressedData.Add((byte)0);
}
}
if (NoCompression == (DefaultCompression & compression))
{
bool testDelDel = ((compression & 0x20) != 0);
compression =
this.GorillaCodec.FindPacketAlgoByte(input, testDelDel);
DeltaDelta dtxf = null;
if ((compression & 0x20) != 0)
{
dtxf = this.DeltaDelta;
}
int inputIndex = 0;
if (null != dtxf)
{
//multibyteencode the first two values
int xfData = 0;
int xfExtra = 0;
dtxf.ResetState();
dtxf.Transform(input[0], ref xfData, ref xfExtra);
this.MultiByteCodec.SignEncode(xfData, compressedData);
dtxf.Transform(input[1], ref xfData, ref xfExtra);
this.MultiByteCodec.SignEncode(xfData, compressedData);
//advance to the third member, we've already read the first two
inputIndex = 2;
}
//Gorllia time
int bitCount = (compression & 0x1F);
this.GorillaCodec.Compress(bitCount, //the max count of bits required for each int
input, //the input array to compress
inputIndex, //the index to start compressing at
dtxf, //data transform to use when compressing, can be null
compressedData); //a ref to the compressed data that will be written to
}
// compression / algo data always goes in index 0
compressedData[0] = compression;
return(compressedData.ToArray());
}
/// <summary>
/// DecompressPacketData - given a compressed byte[], uncompress it to the outputBuffer
/// </summary>
/// <param name="input">compressed byte from the ISF stream</param>
/// <param name="outputBuffer">prealloc'd buffer to write to</param>
/// <returns></returns>
internal uint DecompressPacketData(byte[] input, int[] outputBuffer)
{
if (input == null)
{
throw new ArgumentNullException("input");
}
if (input.Length < 2)
{
throw new ArgumentException(StrokeCollectionSerializer.ISFDebugMessage("Input buffer passed was shorter than expected"));
}
if (outputBuffer == null)
{
throw new ArgumentNullException("outputBuffer");
}
if (outputBuffer.Length == 0)
{
throw new ArgumentException(StrokeCollectionSerializer.ISFDebugMessage("output buffer length was zero"));
}
byte compression = input[0];
uint totalBytesRead = 1; //we just read one
int inputIndex = 1;
switch (compression & 0xC0)
{
case 0x80: //IndexedHuffman
{
DataXform dtxf = this.HuffModule.FindDtXf(compression);
HuffCodec huffCodec = this.HuffModule.FindCodec(compression);
totalBytesRead += huffCodec.Uncompress(dtxf, input, inputIndex, outputBuffer);
return(totalBytesRead);
}
case 0x00: //NoCompression
{
int outputBufferIndex = 0;
DeltaDelta dtxf = null;
if ((compression & 0x20) != 0)
{
dtxf = this.DeltaDelta;
}
int bitCount = 0;
if ((compression & 0x1F) == 0)
{
bitCount = Native.BitsPerInt; //32
}
else
{
bitCount = (compression & 0x1F);
}
if (null != dtxf)
{
//must have at least two more bytes besides the
//initial algo byte
if (input.Length < 3)
{
throw new ArgumentException(StrokeCollectionSerializer.ISFDebugMessage("Input buffer was too short (must be at least 3 bytes)"));
}
//multibyteencode the first two values
int xfData = 0;
int xfExtra = 0;
dtxf.ResetState();
uint bytesRead =
this.MultiByteCodec.SignDecode(input, inputIndex, ref xfData);
//advance our index
inputIndex += (int)bytesRead;
totalBytesRead += bytesRead;
int result = dtxf.InverseTransform(xfData, xfExtra);
Debug.Assert(outputBufferIndex < outputBuffer.Length);
outputBuffer[outputBufferIndex++] = result;
bytesRead =
this.MultiByteCodec.SignDecode(input, inputIndex, ref xfData);
//advance our index
inputIndex += (int)bytesRead;
totalBytesRead += bytesRead;
result = dtxf.InverseTransform(xfData, xfExtra);
Debug.Assert(outputBufferIndex < outputBuffer.Length);
outputBuffer[outputBufferIndex++] = result;
}
totalBytesRead +=
this.GorillaCodec.Uncompress(bitCount, //the max count of bits required for each int
input, //the input array to uncompress
inputIndex, //the index to start uncompressing at
dtxf, //data transform to use when compressing, can be null
outputBuffer, //a ref to the output buffer to write to
outputBufferIndex); //the index of the output buffer to write to
return(totalBytesRead);
}
default:
{
throw new ArgumentException(StrokeCollectionSerializer.ISFDebugMessage("Invalid decompression algo byte"));
}
}
}