def parseSerialMsg(self, msgBytes, msgStart):
"""Searches raw serial data for HDLC messages and then validates message integrity by comparing a computed CRC to the CRC found in the message. Valid messages are then stored for processing.
Args:
msgBytes: Raw serial data to be parsed.
msgStart: Start location to begin looking for serial message in msgBytes data array.
"""
if len(msgBytes) > 0:
# Process serial message
self.msg.decodeMsg(msgBytes, msgStart)
if self.msg.msgFound == True: # Message start found
if self.msg.msgEnd != -1: # entire msg found
# Check msg CRC
crc = self.crc(self.msg.msg[:-self.crcLength])
if self.msg.msg[-self.crcLength:] == packData(
crc,
self.crcLength): # CRC matches - valid message
#print("CRC matches")
self.parsedMsgs.append(self.msg.msg[:-self.crcLength])
return self.msg.msgEnd
else: # partial msg found
pass
else: # No message found
pass
return len(
msgBytes) # all bytes parsed so return length of input message
else:
return 0
def encodeMsg(self, inputMsg):
"""Encodes provided serial data into an HDLC message.
Args:
inputMsg: Serial bytes to be encoded into HDLC message.
"""
if not inputMsg: # Check for empty msg
return
# Create crc
crc = self.crc(inputMsg)
inputMsg = inputMsg + packData(crc, self.crcLength)
outMsg = bytearray()
outMsg += HDLC_END # start message
for i in range(len(inputMsg)):
byte = inputMsg[i:i + 1]
if (byte == HDLC_END): # Replace END character
outMsg += HDLC_ESC
outMsg += HDLC_END_SHIFTED
elif (byte == HDLC_ESC): # Replace ESC character
outMsg += HDLC_ESC
outMsg += HDLC_ESC_SHIFTED
elif (byte == HDLC_END_TDMA): # Replace TDMA END character
outMsg += HDLC_ESC
outMsg += HDLC_END_TDMA_SHIFTED
else: # Insert raw message byte
outMsg += byte
outMsg += HDLC_END # end message
self.encoded = outMsg
def encodeMsg(self, byteList):
"""Encodes provided serial data into a SLIP message.
Args:
byteList: Serial bytes to be encoded into SLIP message.
"""
if not byteList: # Check for empty msg
return
# Create crc
crc = self.crc(byteList)
byteList = byteList + packData(crc, self.crcLength)
self.encoded = b''
self.encoded += SLIP_END
for i in range(len(byteList)):
byte = byteList[i:i + 1]
if byte == SLIP_END: # Replace END character
self.encoded += SLIP_ESC + SLIP_ESC_END
elif byte == SLIP_ESC: # Replace ESC character
self.encoded += SLIP_ESC + SLIP_ESC_ESC
#elif byte == SLIP_END_TDMA: # Replace TDMA END character
# self.encoded += SLIP_ESC + SLIP_ESC_END_TDMA
else: # Insert raw byte into message
self.encoded += byte
self.encoded += SLIP_END
def encodeMsg(self, msgBytes):
if msgBytes: # Add CRC
crc = self.crc(msgBytes)
msgBytes = msgBytes + packData(crc, self.crcLength)
self.msg.encodeMsg(msgBytes)
return self.msg.hdlc
return msgBytes
def parseMsg(self, msgBytes, msgStart):
if len(msgBytes) > 0:
# Process serial message
self.decodeMsg(msgBytes, msgStart)
if self.msgFound == True: # Message start found
if self.msgEnd != -1: # entire msg found
# Check msg CRC
crc = self.crc(self.msg[:-self.crcLength])
if self.msg[-self.crcLength:] == packData(
crc,
self.crcLength): # CRC matches - valid message
#print("CRC matches")
return self.msg[:-self.crcLength]
return [] # no message found
def setup_method(self, method):
self.hdlcMsg = HDLCMsg(256)
self.truthCRC = packData(self.hdlcMsg.crc(testMsg),
self.hdlcMsg.crcLength)
pass
def setup_method(self, method):
self.slipMsg = SLIPMsg(256)
self.truthCRC = packData(self.slipMsg.crc(testMsg), self.slipMsg.crcLength)
pass
