/// <summary>
/// Processes the marshal buffer header and decompress the data if needed
/// </summary>
/// <exception cref="InvalidDataException">If the header is not a correct marshal header</exception>
protected virtual void ProcessPacketHeader()
{
// check the header and ensure we use the correct stream to read from it
byte header = (byte)this.mStream.ReadByte();
if (header == Specification.ZLIB_HEADER)
{
this.mStream.Seek(-1, SeekOrigin.Current);
this.mStream = ZlibHelper.DecompressStream(this.mStream);
header = (byte)this.mStream.ReadByte();
}
if (header != Specification.MARSHAL_HEADER)
{
throw new InvalidDataException($"Expected Marshal header, but got {header}");
}
// create the reader
this.mReader = new BinaryReader(this.mStream);
// read the save list information
int saveCount = this.mReader.ReadInt32();
// check if there are elements in the save list and parse the list-map first
if (saveCount > 0)
{
// compressed streams cannot be seek'd so ensure that the stream is decompressed first
if (this.mStream is ZInputStream)
{
MemoryStream newStream = new MemoryStream();
this.mStream.CopyTo(newStream);
this.mStream = newStream;
this.mReader = new BinaryReader(this.mStream);
this.mStream.Seek(0, SeekOrigin.Begin);
}
// reserve space for the savelist map and the actual elements in the save list
this.mSavedElementsMap = new int[saveCount];
this.mSavedList = new PyDataType[saveCount];
long currentPosition = this.mStream.Position;
// read at the end of the stream to get the correct index to element mapping
this.mStream.Seek(-saveCount * 4, SeekOrigin.End);
for (int i = 0; i < saveCount; i++)
{
this.mSavedElementsMap[i] = this.mReader.ReadInt32();
}
// go back to where the stream was after reading the amount of saved elements
this.mStream.Seek(currentPosition, SeekOrigin.Begin);
}
}