def getPacket(self): """ Adds start token, header and CRC to payload. Escapes bytes. """ # Construct the packet for CRC calculation packet = [] packet.append(self.protocolMajor) packet.append(self.protocolMinor) packet.append(int(self.messageType)) packet += self.payload # Calculate the CRC of the packet packetCrc = crc16ccitt(packet) # Append the CRC to the base packet to escape the entire thing packet += Conversion.uint16_to_uint8_array(packetCrc) # Prepend the size field. sizeField = len(packet) packet = Conversion.uint16_to_uint8_array(sizeField) + packet # Escape everything except the start token packet = self.escapeCharacters(packet) # Prepend the start token. packet = [START_TOKEN] + packet return packet
def process(self):
"""
Process a buffer.
Check CRC, and emit a uart packet.
Buffer starts after size header, and includes wrapper header and tail (CRC).
Return: processing success
"""
# Check size
bufferSize = len(self.buffer)
wrapperSize = WRAPPER_HEADER_SIZE + CRC_SIZE
if bufferSize < wrapperSize:
_LOGGER.warning("Buffer too small")
return False
# Get the buffer between size field and CRC:
baseBuffer = self.buffer[0 : bufferSize - CRC_SIZE]
# Check CRC
calculatedCrc = crc16ccitt(baseBuffer)
sourceCrc = Conversion.uint8_array_to_uint16(self.buffer[bufferSize - CRC_SIZE : ])
if calculatedCrc != sourceCrc:
_LOGGER.warning("Failed CRC: {0} != {1} (data: {2})".format(calculatedCrc, sourceCrc, baseBuffer))
UartEventBus.emit(DevTopics.uartNoise, "crc mismatch")
return False
wrapperPacket = UartWrapperPacket()
if wrapperPacket.parse(baseBuffer):
UartEventBus.emit(SystemTopics.uartNewPackage, wrapperPacket)
return True
def filterhash(self):
"""
Flatten the filter settings and the uint16 array of fingerprints
to a uint8 array in little endian and return a crc16 of the result.
Must match firmware.
returns: FingerprintType
"""
return crc16ccitt(self.serialize())
def process(self):
"""
Process a buffer.
Check CRC, and emit a uart packet.
Buffer starts after size header, and includes wrapper header and tail (CRC).
"""
# Check size
bufferSize = len(self.buffer)
wrapperSize = WRAPPER_HEADER_SIZE + CRC_SIZE
if bufferSize < wrapperSize:
_LOGGER.warning("Buffer too small")
UartEventBus.emit(DevTopics.uartNoise, "buffer too small")
return
# Get the buffer between size field and CRC:
baseBuffer = self.buffer[0:bufferSize - CRC_SIZE]
# Check CRC
calculatedCrc = crc16ccitt(baseBuffer)
sourceCrc = Conversion.uint8_array_to_uint16(self.buffer[bufferSize -
CRC_SIZE:])
if calculatedCrc != sourceCrc:
_LOGGER.warning("Failed CRC")
_LOGGER.debug(
f"Failed CRC: sourceCrc={sourceCrc} calculatedCrc={calculatedCrc} bufSize={len(self.buffer)} buffer={self.buffer}"
)
UartEventBus.emit(DevTopics.uartNoise, "crc mismatch")
return
wrapperPacket = UartWrapperPacket()
if wrapperPacket.parse(baseBuffer):
UartEventBus.emit(SystemTopics.uartNewPackage, wrapperPacket)
def calculateChecksum(self):
self.checksum = crc16ccitt(self.buffer)
print(f"CRC: used: {hex(self.checksum)}")
def calculateChecksum(self):
self.checksum = crc16ccitt(self.chunk)
print(f"Chunk CRC: {hex(self.checksum)}")
def test_crc16_ccitt():
assert (crc16ccitt([1, 2, 3, 4, 5]) == 37636)
assert (crc16ccitt([63, 63]) == 53016)
assert (crc16ccitt([99, 51]) == 17734)
assert (crc16ccitt([170, 251]) == 45518)
def hash_to_fingerprint(self, key):
"""
key: ByteArrayType
returns: FingerprintType
"""
return crc16ccitt(key)
