/// <summary>
/// Decompress the virtual channel data into decompressedBuffer buffer.
/// After decompressing the last pdu, the member decompressedBuffer contains
/// the complete virtual data.
/// </summary>
/// <param name="pdu">The virtual channel pdu includes header and data.</param>
/// <returns>If the reassemble is complete, then return the completePdu. Else return null.</returns>
internal Virtual_Channel_Complete_Pdu ReassembleChunkData(Virtual_Channel_RAW_Pdu pdu)
{
if (pdu == null || pdu.virtualChannelData == null)
{
return null;
}
// the first chunk
if ((pdu.channelPduHeader.flags & CHANNEL_PDU_HEADER_flags_Values.CHANNEL_FLAG_FIRST)
== CHANNEL_PDU_HEADER_flags_Values.CHANNEL_FLAG_FIRST)
{
completePdu = new Virtual_Channel_Complete_Pdu();
completePdu.rawPdus = new System.Collections.ObjectModel.Collection<Virtual_Channel_RAW_Pdu>();
completePdu.channelId = channelId;
decompressedBuffer.Clear();
}
byte[] decompressedData = pdu.virtualChannelData;
if (mppcDecompressor != null) // has compression
{
CompressMode flag = CompressMode.None;
if ((pdu.channelPduHeader.flags & CHANNEL_PDU_HEADER_flags_Values.CHANNEL_PACKET_AT_FRONT)
== CHANNEL_PDU_HEADER_flags_Values.CHANNEL_PACKET_AT_FRONT)
{
flag |= CompressMode.SetToFront;
}
if ((pdu.channelPduHeader.flags & CHANNEL_PDU_HEADER_flags_Values.CHANNEL_PACKET_COMPRESSED)
== CHANNEL_PDU_HEADER_flags_Values.CHANNEL_PACKET_COMPRESSED)
{
flag |= CompressMode.Compressed;
}
if ((pdu.channelPduHeader.flags & CHANNEL_PDU_HEADER_flags_Values.CHANNEL_PACKET_FLUSHED)
== CHANNEL_PDU_HEADER_flags_Values.CHANNEL_PACKET_FLUSHED)
{
flag |= CompressMode.Flush;
}
if (flag != CompressMode.None)
{
decompressedData = mppcDecompressor.Decompress(pdu.virtualChannelData, flag);
}
}
if (completePdu != null)
{
completePdu.rawPdus.Add(pdu);
decompressedBuffer.AddRange(decompressedData);
}
else
{
// not need to reassemble
Virtual_Channel_Complete_Pdu returnPDU = new Virtual_Channel_Complete_Pdu();
returnPDU.rawPdus = new System.Collections.ObjectModel.Collection<Virtual_Channel_RAW_Pdu>();
returnPDU.channelId = channelId;
returnPDU.rawPdus.Add(pdu);
returnPDU.virtualChannelData = decompressedData;
return returnPDU;
}
// the last chunk
if ((pdu.channelPduHeader.flags & CHANNEL_PDU_HEADER_flags_Values.CHANNEL_FLAG_LAST)
== CHANNEL_PDU_HEADER_flags_Values.CHANNEL_FLAG_LAST)
{
if (decompressedBuffer != null)
{
completePdu.virtualChannelData = decompressedBuffer.ToArray();
}
Virtual_Channel_Complete_Pdu returnPDU = completePdu;
completePdu = null;
return returnPDU;
}
return null;
}
