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fix: stop lpp zero tail

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Janez T
2026-03-05 20:12:09 +01:00
parent 03c0c7ad38
commit 2b34bc4162
2 changed files with 34 additions and 0 deletions
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16
lib/services/cayenne_lpp_parser.dart
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@@ -25,6 +25,14 @@ class CayenneLppParser {
int fieldCount = 0;
while (reader.hasRemaining) {
if (fieldCount > 0 && _isZeroPaddedTail(data, reader.remainingBytesCount)) {
debugPrint(
' Detected zero-padded telemetry tail, stopping parse at position '
'${data.length - reader.remainingBytesCount}',
);
break;
}
try {
fieldCount++;
debugPrint(
@@ -250,6 +258,14 @@ class CayenneLppParser {
return ((voltage - 3.0) / 1.2) * 100.0;
}
static bool _isZeroPaddedTail(Uint8List data, int remainingBytes) {
final start = data.length - remainingBytes;
for (int i = start; i < data.length; i++) {
if (data[i] != 0) return false;
}
return remainingBytes > 0;
}
/// Create Cayenne LPP data for GPS location
/// Standard Cayenne LPP GPS format (type 0x88):
/// - Latitude: 3 bytes, signed 24-bit, big-endian, × 10000

18
test/services/cayenne_lpp_parser_test.dart
View File

@@ -410,6 +410,24 @@ void main() {
expect(decoded.batteryMilliVolts, closeTo(3850, 1));
});
test('stops parsing at zero-padded telemetry tail', () {
final payload = Uint8List.fromList([
0x01, 0x74, 0x01, 0x5F, // voltage 3.51V
0x01, 0x88, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00,
]);
final decoded = CayenneLppParser.parse(payload);
expect(decoded.batteryMilliVolts, closeTo(3510, 1));
expect(decoded.batteryPercentage, closeTo(42.5, 0.1));
expect(decoded.gpsLocation, isNotNull);
expect(decoded.gpsLocation!.latitude, 0.0);
expect(decoded.gpsLocation!.longitude, 0.0);
expect(decoded.extraSensorData?['digital_input_0'], isNull);
});
test('empty data returns empty telemetry', () {
final empty = Uint8List(0);
final decoded = CayenneLppParser.parse(empty);