refactored

ubx.py

@@ -0,0 +1,167 @@
+import struct
+
+# ---------------------------------------------------------------------------
+# UBX Protokoll-Konstanten
+# ---------------------------------------------------------------------------
+UBX_SYNC1         = 0xB5
+UBX_SYNC2         = 0x62
+UBX_CLASS_NAV     = 0x01
+UBX_ID_NAV_SAT    = 0x35
+UBX_ID_NAV_SVINFO = 0x30
+UBX_SYNC_WORD = b'\xb5\x62'
+
+
+def checksum(data: bytes) -> bytes:
+	ck_a = 0
+	ck_b = 0
+	for i in range(len(data)):
+		ck_a = (ck_a + data[i]) & 0xFF
+		ck_b = (ck_b + ck_a) & 0xFF
+
+	return struct.pack("BB", ck_a, ck_b)
+
+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):
+	_data = None
+	_hdr = Hdr(0,0,0)
+
+	while True:
+		_hdr = frame_parse_hdr(frame[0:4])
+		if _hdr is None:
+			break
+
+		if (4+_hdr.length+2) != len(frame):
+			break
+
+		_check_soll = frame[-2:]
+		_check_ist = checksum(frame[0:-2])
+		if _check_soll != _check_ist:
+			break
+
+		_data = frame[4:-2]
+		break
+
+	return _data, _hdr
+
+class UbxPacketizer:
+	def __init__(self, sync_bytes: bytes = UBX_SYNC_WORD):
+		self.sync_bytes = sync_bytes
+		self.packet = b''
+		self.wait_sync = True
+		self.sync_count = 0
+		self.d_save = b''
+
+	def reset(self):
+		self.packet = b''
+		self.wait_sync = True
+		self.sync_count = 0
+
+	def on_recv(self, msg: bytes):
+		frames = []
+		for d in msg:
+			if d == self.sync_bytes[self.sync_count]:
+				self.d_save += struct.pack('B', d)
+				self.sync_count += 1
+				if self.sync_count == len(self.sync_bytes):
+					self.sync_count = 0
+					self.d_save = b''
+					self.packet = b''
+					self.wait_sync = False
+			else:
+				if self.sync_count > 0:
+					self.packet += self.d_save
+					self.d_save = b''
+					self.sync_count = 0
+				if not self.wait_sync:
+					self.packet += struct.pack('B', d)
+					data, hdr = frame_parse(self.packet)
+					if data is not None:
+						if hdr.length == len(data):
+							frames.append({"cls": hdr.mclass, "id": hdr.mid, "payload": data})
+							self.packet = b''
+							self.wait_sync = True
+		return frames
+
+# ---------------------------------------------------------------------------
+# UBX Hilfsfunktionen
+# ---------------------------------------------------------------------------
+def ubx_checksum(payload: bytes) -> tuple[int, int]:
+	ck_a = ck_b = 0
+	for b in payload:
+		ck_a = (ck_a + b) & 0xFF
+		ck_b = (ck_b + ck_a) & 0xFF
+	return ck_a, ck_b
+
+def build_ubx(cls: int, msg_id: int, payload: bytes = b"") -> bytes:
+	header = bytes([UBX_SYNC1, UBX_SYNC2, cls, msg_id])
+	length = struct.pack("<H", len(payload))
+	raw = bytes([cls, msg_id]) + length + payload
+	ck_a, ck_b = ubx_checksum(raw)
+	return header + length + payload + bytes([ck_a, ck_b])
+
+def build_poll(cls: int, msg_id: int) -> bytes:
+	return build_ubx(cls, msg_id, b"")
+
+def parse_nav_sat(payload: bytes) -> list[dict]:
+	if len(payload) < 8:
+		return []
+	num_svs = payload[5]
+	sats = []
+	for n in range(num_svs):
+		off = 8 + n * 12
+		if off + 12 > len(payload):
+			break
+		gnss_id, sv_id, cno, elev, azim, _, flags = struct.unpack_from(
+			"<BBBBhhI", payload[off:off + 12]
+		)
+		sats.append({
+			"gnssId": gnss_id, "svId": sv_id, "cno": cno,
+			"elev": elev, "azim": azim, "used": bool(flags & 0x08),
+		})
+	return sats
+
+def parse_nav_svinfo(payload: bytes) -> list[dict]:
+	if len(payload) < 8:
+		return []
+	num_ch = payload[4]
+	sats = []
+	for n in range(num_ch):
+		off = 8 + n * 12
+		if off + 12 > len(payload):
+			break
+		_, svid, flags, _, cno, elev, azim, _ = struct.unpack_from(
+			"<BBBBBbhI", payload, off
+		)
+		sats.append({
+			"gnssId": 0, "svId": svid, "cno": cno,
+			"elev": elev, "azim": azim, "used": bool(flags & 0x01),
+		})
+	return sats
+
+def extract_satellites(frames: list[dict]) -> list[dict]:
+	for f in frames:
+		if f["cls"] == UBX_CLASS_NAV and f["id"] == UBX_ID_NAV_SAT:
+			return parse_nav_sat(f["payload"])
+		if f["cls"] == UBX_CLASS_NAV and f["id"] == UBX_ID_NAV_SVINFO:
+			return parse_nav_svinfo(f["payload"])
+	return []
+
+