private BacnetMstpProtocolTransport.GetMessageStatus GetNextMessage(byte[] buffer, ref int offset,
int timeoutMs, out BacnetPtpFrameTypes frameType, out int msgLength)
{
BacnetMstpProtocolTransport.GetMessageStatus status;
var timeout = timeoutMs;
frameType = BacnetPtpFrameTypes.FRAME_TYPE_HEARTBEAT_XOFF;
msgLength = 0;
var complimentNext = false;
//fetch header
while (offset < PTP.PTP_HEADER_LENGTH)
{
if (_port == null)
{
return(BacnetMstpProtocolTransport.GetMessageStatus.ConnectionClose);
}
timeout = offset > 0 ? T_FRAME_ABORT : timeoutMs;
//read
var rx = _port.Read(buffer, offset, PTP.PTP_HEADER_LENGTH - offset, timeout);
status = ProcessRxStatus(buffer, ref offset, rx);
if (status != BacnetMstpProtocolTransport.GetMessageStatus.Good)
{
return(status);
}
//remove XON/XOFF
var newOffset = offset + rx;
RemoveXonOff(buffer, offset, ref newOffset, ref complimentNext);
offset = newOffset;
//remove garbage
RemoveGarbage(buffer, ref offset);
}
//greeting
if (IsGreeting(buffer, 0, offset))
{
//get last byte
var rx = _port.Read(buffer, offset, 1, timeout);
status = ProcessRxStatus(buffer, ref offset, rx);
if (status != BacnetMstpProtocolTransport.GetMessageStatus.Good)
{
return(status);
}
offset += 1;
if (IsGreeting(buffer, 0, offset))
{
frameType = BacnetPtpFrameTypes.FRAME_TYPE_GREETING;
Log.AddCustomEvent(LagoVista.Core.PlatformSupport.LogLevel.Message, "BacnetPtpProtocol", frameType.ToString());
return(BacnetMstpProtocolTransport.GetMessageStatus.Good);
}
//drop message
buffer[0] = 0xFF;
RemoveGarbage(buffer, ref offset);
return(BacnetMstpProtocolTransport.GetMessageStatus.DecodeError);
}
//decode
if (PTP.Decode(buffer, 0, offset, out frameType, out msgLength) < 0)
{
//drop message
buffer[0] = 0xFF;
RemoveGarbage(buffer, ref offset);
return(BacnetMstpProtocolTransport.GetMessageStatus.DecodeError);
}
//valid length?
var fullMsgLength = msgLength + PTP.PTP_HEADER_LENGTH + (msgLength > 0 ? 2 : 0);
if (msgLength > MaxBufferLength)
{
//drop message
buffer[0] = 0xFF;
RemoveGarbage(buffer, ref offset);
return(BacnetMstpProtocolTransport.GetMessageStatus.DecodeError);
}
//fetch data
if (msgLength > 0)
{
timeout = T_FRAME_ABORT; //set sub timeout
while (offset < fullMsgLength)
{
//read
var rx = _port.Read(buffer, offset, fullMsgLength - offset, timeout);
status = ProcessRxStatus(buffer, ref offset, rx);
if (status != BacnetMstpProtocolTransport.GetMessageStatus.Good)
{
return(status);
}
//remove XON/XOFF
var newOffset = offset + rx;
RemoveXonOff(buffer, offset, ref newOffset, ref complimentNext);
offset = newOffset;
}
//verify data crc
if (PTP.Decode(buffer, 0, offset, out frameType, out msgLength) < 0)
{
//drop message
buffer[0] = 0xFF;
RemoveGarbage(buffer, ref offset);
return(BacnetMstpProtocolTransport.GetMessageStatus.DecodeError);
}
}
Log.AddCustomEvent(LagoVista.Core.PlatformSupport.LogLevel.Message, "BacnetPtpProtocol", frameType.ToString());
//done
return(BacnetMstpProtocolTransport.GetMessageStatus.Good);
}
private void SendFrame(BacnetPtpFrameTypes frameType, byte[] buffer = null, int msgLength = 0)
{
if (_port == null)
{
return;
}
var fullLength = PTP.PTP_HEADER_LENGTH + msgLength + (msgLength > 0 ? 2 : 0);
if (buffer == null)
{
buffer = new byte[fullLength];
}
PTP.Encode(buffer, 0, frameType, msgLength);
Log.AddCustomEvent(LagoVista.Core.PlatformSupport.LogLevel.Message, "BacnetPtpProtocol", frameType.ToString());
//send
SendWithXonXoff(buffer, 0, fullLength);
}