- added ubx parse

- fixed ubx create

ubx/ubx.py

@@ -10,17 +10,37 @@ def checksum(data: bytes) -> bytes:
 
 	return struct.pack("BB", ck_a, ck_b)
 
-def frame_create(msg_class: int, msg_id: int, payload: bytes) -> bytes:
+def frame_create(_class: int, _id: int, _data: bytes) -> bytes:
 	hdr = b'\xb5\x62'
-	frame = struct.pack('B', msg_class)
-	frame += struct.pack('B', msg_id)
-	frame += struct.pack('<H', len(payload))
-	frame += payload
+	frame = struct.pack('B', _class)
+	frame += struct.pack('B', _id)
+	frame += struct.pack('<H', len(_data))
+	frame += _data
 	check = checksum(frame)
 
-	return hdr + payload + check
+	return hdr + frame + check
 
+def frame_parse(frame: bytes):
+	hdr = frame[0:2]
+	if hdr != b'\xb5\x62':
+		return None
+
+	_class = struct.unpack('B', frame[2:3])[0]
+	_id = struct.unpack('B', frame[3:4])[0]
+	_length = struct.unpack('<H', frame[4:6])[0]
+	if (6+_length+2) != len(frame):
+		return None
+
+	_data = frame[6:-2]
+	_check_soll = frame[-2:]
+	_check_ist = checksum(frame[2:-2])
+	if _check_soll != _check_ist:
+		return None
+
+	return _data, _class, _id
 
 if __name__ == "__main__":
 	result = frame_create(1, 2, b'Hallo')
 	print(result)
+	payload, msg_class, msg_id = frame_parse(result)
+	print(payload)