refactored

network_backend.py

@@ -5,6 +5,7 @@ import time
 from msg_container import MsgContainer
 from receiver.nmea_packetizer import NmeaPacketizer
 from receiver.ubx_packetizer import UbxPacketizer
+from receiver.ubx_receiver import UbxReceiver
 from transceiver import Transceiver
 from a_backend import ABackend
 from nmea.GLL import Gll
@@ -12,7 +13,6 @@ from nmea.GSA import Gsa
 from nmea.GSV import Gsv
 from nmea.GGA import Gga
 from nmea.RMC import Rmc
-from ubx.ubx import UbxReceiver
 
 
 class NetworkBackend(ABackend):
@@ -116,7 +116,7 @@ if __name__ == "__main__":
 
 		# Create NMEA-Packetizer
 		nmea_packetizer = NmeaPacketizer()
-		ubx_packetizer = UbxPacketizer(sync_bytes=b'\xb5\x62')
+		ubx_packetizer = UbxPacketizer()
 
 		# Register NMEA-Packetizer to transceiver
 		transceiver.register_recv(nmea_packetizer)

receiver/ubx_packetizer.py

@@ -1,34 +1,44 @@
+import struct
 from msg_container import MsgContainer
 from msg_sink import MsgSink
 from msg_source import MsgSource
-from struct import pack
+from ubx.ubx import UBX_SYNC_WORD, frame_parse_hdr, frame_create
+from receiver.ubx_receiver import UbxReceiver
 
 class UbxPacketizer(MsgSink, MsgSource):
-	def __init__(self, sync_bytes: bytes):
+	def __init__(self, sync_bytes: bytes = UBX_SYNC_WORD):
 		MsgSink.__init__(self)
 		MsgSource.__init__(self)
 		self.sync_bytes = sync_bytes
 		self.packet = b''
 		self.wait_sync = True
-		self.latency = None
+		self.sync_count = 0
+
+	def reset(self):
+		self.packet = b''
+		self.wait_sync = True
+		self.sync_count = 0
+
 	def on_recv(self, msg: MsgContainer):
 		name = msg.name
-		data = msg.data
-		w = len(self.sync_bytes)
-		self.latency = 0
-		for n in range (0, len(data)):
-			d = data[n:n+w]
-			if d == self.sync_bytes:
-				self.latency = w-1
-				print("UBX-sync")
 		timestamp = msg.timestamp
+		for n in range (0, len(msg.data)):
+			d = msg.data[n]
+			if d == self.sync_bytes[self.sync_count]:
+				self.sync_count += 1
+				if self.sync_count == len(self.sync_bytes):
+					print("UBX-sync")
+					self.sync_count = 0
+					self.packet = b''
 					self.wait_sync = False
-			elif not self.wait_sync:
-				if self.latency == 0:
-					self.packet += d
 			else:
-					self.latency -= 1
+				if not self.wait_sync:
-
+					self.packet += struct.pack('B', d)
+					hdr = frame_parse_hdr(self.packet)
+					if hdr is not None:
+						if (6 + hdr.length) == len(self.packet):
+							self.call_sinks(MsgContainer(name, timestamp, self.packet))
+							self.packet = b''
 
 
 	def is_msg(self, msg: MsgContainer):
@@ -36,11 +46,21 @@ class UbxPacketizer(MsgSink, MsgSource):
 
 
 if __name__ == "__main__":
-	_sync = b'JA'
+	class MySink(MsgSink):
-	_data = b'31'
+		def __init__(self):
-	pkt = UbxPacketizer(sync_bytes=_sync)
+			MsgSink.__init__(self)
-	frame1 = _sync + b'31' + _sync + b'31'
-	pkt.on_recv(MsgContainer('test', 31101970.0208, frame1))
 
-	frame2 = _sync + b'3' + _sync + b'10'
+		def on_recv(self, msg: MsgContainer):
-	pkt.on_recv(MsgContainer('test', 31101970.0208, frame2))
+			print(msg)
+
+		def is_msg(self, msg: MsgContainer):
+			return True
+
+	ubx_rx = UbxReceiver('test', 1, 2)
+
+	pkt = UbxPacketizer()
+	pkt.register_recv(ubx_rx)
+
+	pkt.reset()
+	frame = frame_create(_class=1, _id=2, _data=b'Hallo') + frame_create(_class=1, _id=2, _data=b',') + frame_create(_class=1, _id=2, _data=b'UBX') + frame_create(_class=1, _id=2, _data=b'World')
+	pkt.on_recv(MsgContainer('test', 31101970.0208, frame))

receiver/ubx_receiver.py

@@ -0,0 +1,20 @@
+from msg_container import MsgContainer
+from msg_sink import MsgSink
+from ubx.ubx import frame_parse, frame_parse_hdr
+
+class UbxReceiver(MsgSink):
+	def __init__(self, name: str, mid: int, mclass: int):
+		MsgSink.__init__(self)
+		self.name = name
+		self.mid = mid
+		self.mclass = mclass
+
+	def on_recv(self, msg: MsgContainer):
+		data, hdr = frame_parse(msg.data)
+		print(f"{hdr.mclass}:{hdr.mid}:{data}")
+
+	def is_msg(self, msg: MsgContainer):
+		hdr = frame_parse_hdr(msg.data)
+		if hdr is not None:
+			return self.mclass == hdr.mclass and self.mid == hdr.mid
+		return False

ubx/ubx.py

@@ -1,8 +1,6 @@
 import struct
 
-from msg_container import MsgContainer
+UBX_SYNC_WORD = b'\xb5\x62'
-from msg_sink import MsgSink
-
 
 def checksum(data: bytes) -> bytes:
 	ck_a = 0
@@ -22,59 +20,49 @@ def frame_create(_class: int, _id: int, _data: bytes) -> bytes:
 
 	return _sync + _hdr + _data + _check
 
+class Hdr:
+	def __init__(self, _class: int, _id: int, _length: int):
+		self.mclass = _class
+		self.mid = _id
+		self.length = _length
+
+
+def frame_parse_hdr(frame: bytes) -> Hdr|None:
+	hdr = Hdr(0,0,0)
+
+	if len(frame) < 4:
+		return None
+
+	hdr.mclass = struct.unpack('B', frame[0:1])[0]
+	hdr.mid = struct.unpack('B', frame[1:2])[0]
+	hdr.length = struct.unpack('<H', frame[2:4])[0]
+
+	return hdr
+
 def frame_parse(frame: bytes):
-	_class = 0
-	_id = 0
 	_data = None
+	_hdr = Hdr(0,0,0)
 
 	while True:
-		hdr = frame[0:2]
+		_hdr = frame_parse_hdr(frame[0:4])
-		if hdr != b'\xb5\x62':
+		if _hdr is None:
 			break
 
-		_class = struct.unpack('B', frame[2:3])[0]
+		if (4+_hdr.length+2) != len(frame):
-		_id = struct.unpack('B', frame[3:4])[0]
-		_length = struct.unpack('<H', frame[4:6])[0]
-		if (6+_length+2) != len(frame):
 			break
 
 		_check_soll = frame[-2:]
-		_check_ist = checksum(frame[2:-2])
+		_check_ist = checksum(frame[0:-2])
 		if _check_soll != _check_ist:
 			break
 
-		_data = frame[6:-2]
+		_data = frame[4:-2]
 		break
 
-	return _data, _class, _id
+	return _data, _hdr
-
-class UbxReceiver(MsgSink):
-	def __init__(self, name: str, mid: int, mclass: int):
-		MsgSink.__init__(self)
-		self.name = name
-		self.mid = mid
-		self.mclass = mclass
-
-	def on_recv(self, msg: MsgContainer):
-		data, mclass, mid = frame_parse(msg.data)
-		print(f"{mclass}:{mid}:{data}")
-
-
-	def is_msg(self, msg: MsgContainer):
-		data, mclass, mid = frame_parse(msg.data)
-		if data is None:
-			return False
-
-		if mclass != self.mclass:
-			return False
-
-		if mid != self.mid:
-			return False
-
-		return True
 
 if __name__ == "__main__":
 	result = frame_create(1, 2, b'Hallo')
 	print(result)
-	payload, msg_class, msg_id = frame_parse(result)
+	payload, hdr = frame_parse(result)
 	print(payload)