public static byte[] GetTerminalResponse(this NetworkStream stream)
{
var buffer = new byte[4096];
int bytesReceived = stream.ReadAsync(buffer, 0, buffer.Length).Result;
if (bytesReceived <= 0)
{
bytesReceived = stream.ReadAsync(buffer, 0, buffer.Length).Result;
}
if (bytesReceived > 0)
{
byte[] readBuffer = new byte[bytesReceived];
Array.Copy(buffer, readBuffer, bytesReceived);
var code = (ControlCodes)readBuffer[0];
if (code == ControlCodes.NAK)
{
return(null);
}
else if (code == ControlCodes.EOT)
{
throw new MessageException("Terminal returned EOT for the current message.");
}
else if (code == ControlCodes.ACK)
{
return(stream.GetTerminalResponse());
}
else if (code == ControlCodes.STX)
{
var queue = new Queue <byte>(readBuffer);
// break off only one message
var rec_buffer = new List <byte>();
do
{
rec_buffer.Add(queue.Dequeue());
if (rec_buffer[rec_buffer.Count - 1] == (byte)ControlCodes.ETX)
{
break;
}
}while (queue.Count > 0);
// Should be the LRC
if (queue.Count > 0)
{
rec_buffer.Add(queue.Dequeue());
}
return(rec_buffer.ToArray());
}
else
{
throw new MessageException(string.Format("Unknown message received: {0}", code));
}
}
return(null);
}
public byte[] Send(IDeviceMessage message)
{
Connect();
using (_stream) {
byte[] buffer = message.GetSendBuffer();
try {
if (OnMessageSent != null)
{
OnMessageSent(message.ToString());
}
for (int i = 0; i < 3; i++)
{
_stream.WriteAsync(buffer, 0, buffer.Length).Wait();
var rvalue = _stream.GetTerminalResponse();
if (rvalue != null)
{
byte lrc = rvalue[rvalue.Length - 1]; // should the the LRC
if (lrc != TerminalUtilities.CalculateLRC(rvalue))
{
SendControlCode(ControlCodes.NAK);
}
else
{
SendControlCode(ControlCodes.ACK);
return(rvalue);
}
}
}
throw new HpsMessageException("Terminal did not respond in the given timeout.");
}
catch (Exception exc) {
throw new HpsMessageException(exc.Message, exc);
}
finally {
Disconnect();
}
}
}
