private bool ReceivePacket()
{
m_rcvState = RcvState.Idle;
m_bufferSize = 0;
int timeout = Environment.TickCount + m_readTimeout;
while (Environment.TickCount < timeout)
{
int read = PortRead(m_tempBuffer, 0, m_tempBuffer.Length);
if (read > 0)
{
if (ProcessData(m_tempBuffer, read))
{
Logging.TraceHex(TraceEventType.Verbose, "Rt Pkt", m_buffer, 0, m_bufferSize);
return(true);
}
}
}
Logging.Trace(TraceEventType.Warning, "Error reading packet from the bus.");
return(false);
}
private bool ProcessData(byte[] buffer, int length)
{
for (int i = 0; i < length; ++i)
{
byte ch = buffer[i];
switch (m_rcvState)
{
case RcvState.Idle:
{
switch (ch)
{
case (byte)ControlChars.DLE:
m_rcvState = RcvState.DLE_START;
break;
case (byte)ControlChars.STX:
m_rcvState = RcvState.Data;
break;
case (byte)ControlChars.NAK:
case (byte)ControlChars.EOT:
m_packetType = PacketType.Command;
m_buffer[m_bufferSize++] = ch;
m_rcvState = RcvState.Done;
break;
}
}
break;
case RcvState.DLE_START:
{
switch (ch)
{
case (byte)ControlChars.STX:
m_rcvState = RcvState.Data;
m_packetType = PacketType.Data;
break;
case (byte)ControlChars.ACK0:
case (byte)ControlChars.ACK1:
m_buffer[m_bufferSize++] = ch;
m_rcvState = RcvState.Done;
m_packetType = PacketType.Command;
break;
}
}
break;
case RcvState.DLE:
{
if (ch == (byte)ControlChars.DLE)
{
m_buffer[m_bufferSize++] = ch;
m_rcvState = RcvState.Data;
}
else if (ch == (byte)ControlChars.ETX || ch == (byte)ControlChars.ETB)
{
m_buffer[m_bufferSize++] = ch;
m_rcvState = RcvState.CHS_1;
}
}
break;
case RcvState.Data:
{
switch (ch)
{
case (byte)ControlChars.DLE:
m_rcvState = RcvState.DLE;
break;
default:
m_buffer[m_bufferSize++] = ch;
break;
}
}
break;
case RcvState.CHS_1:
m_buffer[m_bufferSize++] = ch;
m_rcvState = RcvState.CHS_2;
break;
case RcvState.CHS_2:
{
m_buffer[m_bufferSize++] = ch;
m_rcvState = RcvState.Done;
}
break;
case RcvState.Done:
break;
}
if (m_rcvState == RcvState.Done)
{
return(true);
}
}
return(false);
}
