Fix UPER encoding of CurvatureCalculationMode; verified on hardware

CurvatureCalculationMode is the one extensible ENUMERATED in CAM: ENUMERATED {yawRateUsed(0), yawRateNotUsed(1), unavailable(2), ...} UPER encodes an extensible ENUMERATED as an extension bit followed by the root index - 1 + 2 = 3 bits. All three of our encoders wrote only the 2-bit index, shifting yawRate and the entire low-frequency container one bit early for any standards-compliant receiver. It went unnoticed because every end of this project shared the mistake: the Kotlin codec was ported bit-for-bit from cam.c, so phone and ESP32 agreed perfectly with each other and with nothing else. Confirmed against the ETSI ASN.1 in the C-ITS-Parser checkout, where rasn marks this type - and only this type - #[non_exhaustive]. Fixed in all three copies of the encoder (app CamUperCodec.kt, obu-firmware/main/cam.c, obu-cam-transmistter/main/cam.c) plus the decoder, which now rejects rather than misreads a set extension bit. Frame size is unchanged at 43 bytes. Transmitter reflashed and the phone decodes its CAMs. Also in this change: - serial_link: skip send_frame entirely when no USB host is attached, and raise the tx mutex timeout above the worst-case hold. With the phone unplugged every write blocked its full timeout while holding the lock, so forwarded CAM_RX traffic starved the 1 Hz heartbeat - observed as "tx mutex timeout, dropping frame" on the console, and it would have tripped the phone's link watchdog. Verified gone on hardware. - Log decoded and failed CAMs in CamUseCaseRepository. "The app shows nothing" had two indistinguishable causes; a silent `?: return` made this bug much harder to find than it needed to be. - Remove the ESP32 send-only/send-and-receive toggle. Reception can't be disabled in firmware (raw TX only works while promiscuous), so it was an app-side filter pretending to be a radio control. - V2X monitor follows the serial link state on the ESP32 path instead of MQTT, which is permanently disconnected there; CAM intake is gated on the link being up, and engine state is cleared when it drops. - About screen: 0.5.0, Phase 03. - Track obu-cam-transmistter, the bench CAM transmitter. Its cam.c is compiled (unlike obu-firmware's reference copy) and must stay bit-identical to the other two - this commit is what that coupling costs when it's broken. - Document the two-toolchain split: this project builds on IDF 5.5.4, obu-firmware on the pinned 6.1. Exporting both in one shell fails confusingly. Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
2026-08-11 14:50:35 +02:00
parent f3ae81a8fe
commit 528637dab6
32 changed files with 3852 additions and 133 deletions
@@ -0,0 +1,153 @@
+#include "denm.h"
+#include <string.h>
+
+// Minimal MSB-first bit packer - ASN.1 UPER is a bitstream, not a byte
+// stream, so we can't just memcpy structs.
+typedef struct {
+    uint8_t *buf;
+    size_t buf_len;
+    size_t bit_pos;
+} bitwriter_t;
+
+static void bw_init(bitwriter_t *bw, uint8_t *buf, size_t len)
+{
+    bw->buf = buf;
+    bw->buf_len = len;
+    bw->bit_pos = 0;
+    memset(buf, 0, len);
+}
+
+static void bw_put_bits(bitwriter_t *bw, uint64_t value, int nbits)
+{
+    for (int i = nbits - 1; i >= 0; i--) {
+        size_t byte_idx = bw->bit_pos / 8;
+        int bit_idx = 7 - (int)(bw->bit_pos % 8);
+        if (byte_idx >= bw->buf_len) {
+            return; // overflow guard - silently truncates, check return value of denm_encode
+        }
+        uint8_t bit = (value >> i) & 1;
+        bw->buf[byte_idx] = (uint8_t)(bw->buf[byte_idx] | (bit << bit_idx));
+        bw->bit_pos++;
+    }
+}
+
+static size_t bw_byte_len(const bitwriter_t *bw)
+{
+    return (bw->bit_pos + 7) / 8;
+}
+
+int denm_encode(const denm_fields_t *f, uint8_t *buf, size_t buf_len)
+{
+    bitwriter_t bw;
+    bw_init(&bw, buf, buf_len);
+
+    // ---- ItsPduHeader ---- (SEQUENCE, no OPTIONALs, no "..." -> no preamble at all)
+    bw_put_bits(&bw, 2, 8);              // protocolVersion INTEGER(0..255) = 2
+    bw_put_bits(&bw, 1, 8);              // messageID INTEGER(0..255) = denm(1)
+    bw_put_bits(&bw, f->station_id, 32); // stationID = StationID INTEGER(0..4294967295) = 32 bits
+
+    // ---- DenmPayload (DecentralizedEnvironmentalNotificationMessage) ----
+    // No "..." on this SEQUENCE -> no extension bit, just the 3-bit
+    // optional-component preamble in declared order: situation, location,
+    // alacarte. "No additional parameters" means location/alacarte stay
+    // absent.
+    bw_put_bits(&bw, 1, 1); // situation present
+    bw_put_bits(&bw, 0, 1); // location absent
+    bw_put_bits(&bw, 0, 1); // alacarte absent
+
+    // ---- ManagementContainer ----
+    // This SEQUENCE ends in "..." in the real ASN.1 module -> extensible,
+    // so it needs a leading 1-bit extension flag (0 = no extension
+    // additions used) BEFORE the 5-bit optional/default preamble
+    // (termination, relevanceDistance, relevanceTrafficDirection,
+    // validityDuration, transmissionInterval, in that declared order). An
+    // earlier version of this code omitted the extension bit entirely,
+    // which would shift every single bit after it and corrupt the whole
+    // rest of the message for any spec-compliant decoder.
+    bw_put_bits(&bw, 0, 1); // ManagementContainer extension bit: none used
+    bw_put_bits(&bw, f->terminate ? 1 : 0, 1); // termination present only when cancelling
+    bw_put_bits(&bw, 0, 1); // relevanceDistance absent
+    bw_put_bits(&bw, 0, 1); // relevanceTrafficDirection absent
+    bw_put_bits(&bw, 0, 1); // validityDuration absent -> default 600s applies
+    bw_put_bits(&bw, 0, 1); // transmissionInterval absent
+
+    // actionID = ActionID{ originatingStationID StationID(32), sequenceNumber
+    // SequenceNumber(0..65535, 16 bits) } - no OPTIONALs/"..." -> no preamble.
+    // Keep sequenceNumber constant across repeats of the SAME event - it's
+    // the caller's job (see main.c) to only bump it on a genuinely new event
+    // and reuse it for that event's eventual termination message.
+    bw_put_bits(&bw, f->station_id, 32);
+    bw_put_bits(&bw, f->sequence_number, 16);
+
+    // detectionTime / referenceTime: TimestampIts INTEGER(0..4398046511103)
+    // = exactly 42 bits (2^42), ms since 2004-01-01T00:00:00Z. NOT WIRED UP
+    // YET - there's no RTC/NTP sync in this skeleton, so this is 0 (decodes
+    // as 2004-01-01). Wire in SNTP or a GNSS UTC fix before this is real.
+    bw_put_bits(&bw, 0, 42);
+    bw_put_bits(&bw, 0, 42);
+
+    // termination VALUE - only emitted when present (per the preamble bit
+    // above - UPER never encodes a value for an absent optional component).
+    // Termination ::= ENUMERATED{isCancellation(0), isNegation(1)}, no
+    // "...", 2 values -> 1 bit.
+    if (f->terminate) {
+        bw_put_bits(&bw, 0, 1); // isCancellation
+    }
+
+    // eventPosition (ReferencePosition ::= SEQUENCE{latitude, longitude,
+    // positionConfidenceEllipse, altitude} - no OPTIONALs/"..." -> no
+    // preamble, straight concatenation). Widths below are each field's
+    // exact constrained-INTEGER range size from ITS-Container.asn, encoded
+    // as an unsigned offset from the type's declared minimum - NOT assumed
+    // to match neighboring fields (latitude and longitude are different
+    // widths, which is easy to miss).
+    //   Latitude ::= INTEGER(-900000000..900000001) -> range 1800000002 -> 31 bits
+    uint32_t lat_offset = (uint32_t)(f->latitude_tenmicrodeg - (-900000000));
+    bw_put_bits(&bw, lat_offset, 31);
+    //   Longitude ::= INTEGER(-1800000000..1800000001) -> range 3600000002 -> 32 bits
+    uint32_t lon_offset = (uint32_t)(f->longitude_tenmicrodeg - (-1800000000));
+    bw_put_bits(&bw, lon_offset, 32);
+    //   PosConfidenceEllipse ::= SEQUENCE{semiMajorConfidence, semiMinorConfidence,
+    //   semiMajorOrientation} - no preamble.
+    //     SemiAxisLength ::= INTEGER(0..4095) -> 12 bits (not 16 - this was wrong before)
+    bw_put_bits(&bw, 4095, 12); // semiMajorConfidence: unavailable
+    bw_put_bits(&bw, 4095, 12); // semiMinorConfidence: unavailable
+    //     HeadingValue ::= INTEGER(0..3601) -> 12 bits (not 16 - this was wrong before)
+    bw_put_bits(&bw, 3601, 12); // semiMajorOrientation: unavailable
+    //   Altitude ::= SEQUENCE{altitudeValue, altitudeConfidence} - no preamble.
+    //     AltitudeValue ::= INTEGER(-100000..800001) -> range 900002 -> 20 bits
+    //     (not 24 - this was wrong before), offset-encoded from -100000.
+    bw_put_bits(&bw, 900001, 20); // 800001 ("unavailable") - (-100000) = 900001
+    //     AltitudeConfidence ::= ENUMERATED, 16 named values, no "..." -> 4 bits
+    bw_put_bits(&bw, 15, 4); // unavailable
+
+    // stationType: StationType INTEGER(0..255) -> 8 bits fixed regardless of
+    // how sparse the named values are.
+    bw_put_bits(&bw, f->station_type, 8);
+
+    // ---- SituationContainer ----
+    // This SEQUENCE also ends in "..." -> its own 1-bit extension flag,
+    // THEN the 2-bit preamble (linkedCause, eventHistory), THEN the
+    // mandatory field values. An earlier version of this code put the
+    // linkedCause/eventHistory bits at the END instead of the start, and
+    // had no extension bit at all - both are structural bugs that would
+    // desync any spec-compliant decoder from this point on.
+    bw_put_bits(&bw, 0, 1); // SituationContainer extension bit: none used
+    bw_put_bits(&bw, 0, 1); // linkedCause absent
+    bw_put_bits(&bw, 0, 1); // eventHistory absent
+
+    // informationQuality: InformationQuality INTEGER(0..7) -> 3 bits
+    bw_put_bits(&bw, 1, 3); // low quality - no real sensor input, just the hazard-light GPIO
+
+    // eventType: CauseCode ::= SEQUENCE{causeCode, subCauseCode, ...} - this
+    // inner SEQUENCE is ALSO extensible ("..."), so it gets its own leading
+    // extension bit before its two mandatory fields.
+    bw_put_bits(&bw, 0, 1);                  // CauseCode extension bit: none used
+    bw_put_bits(&bw, f->cause_code, 8);      // CauseCodeType INTEGER(0..255) -> 8 bits
+    bw_put_bits(&bw, f->sub_cause_code, 8);  // SubCauseCodeType INTEGER(0..255) -> 8 bits
+
+    // linkedCause / eventHistory: both absent, already signalled in the
+    // preamble above - UPER writes no value bits for them.
+
+    return (int)bw_byte_len(&bw);
+}