altoslib: Allow early bail-out on bad telemetry CRC

[fw/altos] / altoslib / AltosTelemetry.java

diff --git a/altoslib/AltosTelemetry.java b/altoslib/AltosTelemetry.java
index fe536c6ac17e4ede763d2bb832b9bb7e1c2f4121..a374519d41c50d34508fb6dc1971ae37ba763b4c 100644 (file)
--- a/altoslib/AltosTelemetry.java
+++ b/altoslib/AltosTelemetry.java
@@ -28,8 +28,11 @@ public abstract class AltosTelemetry implements AltosDataProvider {
        int[]   bytes;
 
        /* All telemetry packets have these fields */
-       public int rssi() { return AltosConvert.telem_to_rssi(AltosLib.int8(bytes, bytes.length - 3)); }
-       public int status() { return AltosLib.uint8(bytes, bytes.length - 2); }
+       static public int rssi(int[] bytes) { return AltosConvert.telem_to_rssi(AltosLib.int8(bytes, bytes.length - 3)); }
+       static public int status(int[] bytes) { return AltosLib.uint8(bytes, bytes.length - 2); }
+
+       public int rssi() { return rssi(bytes); }
+       public int status() { return status(bytes); }
 
        /* All telemetry packets report these fields in some form */
        public abstract int serial();
@@ -96,6 +99,9 @@ public abstract class AltosTelemetry implements AltosDataProvider {
                if (!cksum(bytes))
                        throw new ParseException(String.format("invalid line \"%s\"", hex), 0);
 
+               if ((status(bytes) & PKT_APPEND_STATUS_1_CRC_OK) == 0)
+                       throw new AltosCRCException(rssi(bytes));
+
                /* length, data ..., rssi, status, checksum -- 4 bytes extra */
                switch (bytes.length) {
                case AltosLib.ao_telemetry_standard_len + 4: