fix!: align the wire format with ISO 14229-1:2020

Cargo.toml

@@ -20,20 +20,24 @@ authors = [
 
 [features]
 default = ["std"]
-std = ["alloc", "embedded-io/std", "thiserror/std"]
-alloc = ["embedded-io/alloc"]
-serde = ["dep:serde", "dep:serde_bytes"]
-utoipa = ["dep:utoipa"]
-clap = ["dep:clap"]
+std = ["alloc", "embedded-io/std", "thiserror/std", "serde?/std"]
+alloc = ["embedded-io/alloc", "serde?/alloc"]
+# `serde` is the only optional integration usable on a bare-metal target. It is wired as a
+# core-only dependency (`default-features = false`) and picks up serde's `alloc`/`std` layers
+# only when this crate's own `alloc`/`std` features are on, via weak `serde?/..` features.
+serde = ["dep:serde"]
+# `utoipa` and `clap` both imply `std`. Their derive macros expand to `std::`, `String` and
+# `Vec` paths inside this crate, which cannot compile under `#![no_std]`.
+utoipa = ["std", "dep:utoipa"]
+clap = ["std", "dep:clap"]
 
 [dependencies]
 automotive-wire-codec = { version = "0.3", default-features = false }
 bitmask-enum = "2"
 embedded-io = { version = "0.7", default-features = false }
 thiserror = { version = "2", default-features = false }
 # Optional dependencies
-serde = { version = "1", optional = true, features = ["derive"] }
-serde_bytes = { version = "0.11", optional = true }
+serde = { version = "1", optional = true, default-features = false, features = ["derive"] }
 utoipa = { version = "5", optional = true }
 clap = { version = "4", optional = true, features = ["derive"] }
 

README.md

@@ -13,33 +13,35 @@ It is not in a complete state yet with the 0.1.0 release, please check back soon
 This library provides serialization and deserialization of UDS messages.
 It is based on the ISO 14229-1:2020 standard.
 
-| Service Name                     | Request SID | Response SID | Support |
-| -------------------------------- | ----------- | ------------ | ------- |
-| `DiagnosticSessionControl`       | 0x10        | 0x50         | ✓       |
-| `ECUReset`                       | 0x11        | 0x51         | ✓       |
-| `ClearDiagnosticInformation`     | 0x14        | 0x54         | ✓       |
-| `ReadDTCInformation`             | 0x19        | 0x59         | Partial |
-| `ReadDataByIdentifier`           | 0x22        | 0x62         | ✓       |
-| `ReadMemoryByAddress`            | 0x23        | 0x63         |         |
-| `ReadScalingDataByIdentifier`    | 0x24        | 0x64         |         |
-| `SecurityAccess`                 | 0x27        | 0x67         | ✓       |
-| `CommunicationControl`           | 0x28        | 0x68         | ✓       |
-| `Authentication`                 | 0x29        | 0x69         |         |
-| `ReadDataByPeriodicIdentifier`   | 0x2A        | 0x6A         |         |
-| `WriteDataByIdentifier`          | 0x2E        | 0x6E         | ✓       |
-| `InputOutputControlByIdentifier` | 0x2F        | 0x6F         |         |
-| `RoutineControl`                 | 0x31        | 0x71         | ✓       |
-| `RequestDownload`                | 0x34        | 0x74         | ✓       |
-| `RequestUpload`                  | 0x35        | 0x75         |         |
-| `TransferData`                   | 0x36        | 0x76         | ✓       |
-| `RequestTransferExit`            | 0x37        | 0x77         | ✓       |
-| `RequestFileTransfer`            | 0x38        | 0x78         | ✓       |
-| `WriteMemoryByAddress`           | 0x3D        | 0x7D         |         |
-| `TesterPresent`                  | 0x3E        | 0x7E         | ✓       |
-| `SecuredDataTransmission`        | 0x84        | 0xC4         |         |
-| `ControlDTCSetting`              | 0x85        | 0xC5         | ✓       |
-| `ResponseOnEvent`                | 0x86        | 0xC6         |         |
-| `LinkControl`                    | 0x87        | 0xC7         |         |
+| Service Name                       | Request SID | Response SID | Support |
+| ---------------------------------- | ----------- | ------------ | ------- |
+| `DiagnosticSessionControl`         | 0x10        | 0x50         | ✓       |
+| `EcuReset`                         | 0x11        | 0x51         | ✓       |
+| `ClearDiagnosticInformation`       | 0x14        | 0x54         | ✓       |
+| `ReadDTCInformation`               | 0x19        | 0x59         | Partial |
+| `ReadDataByIdentifier`             | 0x22        | 0x62         | ✓       |
+| `ReadMemoryByAddress`              | 0x23        | 0x63         |         |
+| `ReadScalingDataByIdentifier`      | 0x24        | 0x64         |         |
+| `SecurityAccess`                   | 0x27        | 0x67         | ✓       |
+| `CommunicationControl`             | 0x28        | 0x68         | ✓       |
+| `Authentication`                   | 0x29        | 0x69         |         |
+| `ReadDataByPeriodicIdentifier`     | 0x2A        | 0x6A         |         |
+| `DynamicallyDefinedDataIdentifier` | 0x2C        | 0x6C         |         |
+| `WriteDataByIdentifier`            | 0x2E        | 0x6E         | ✓       |
+| `InputOutputControlByIdentifier`   | 0x2F        | 0x6F         |         |
+| `RoutineControl`                   | 0x31        | 0x71         | ✓       |
+| `RequestDownload`                  | 0x34        | 0x74         | ✓       |
+| `RequestUpload`                    | 0x35        | 0x75         | ✓       |
+| `TransferData`                     | 0x36        | 0x76         | ✓       |
+| `RequestTransferExit`              | 0x37        | 0x77         | ✓       |
+| `RequestFileTransfer`              | 0x38        | 0x78         | ✓       |
+| `WriteMemoryByAddress`             | 0x3D        | 0x7D         |         |
+| `TesterPresent`                    | 0x3E        | 0x7E         | ✓       |
+| `AccessTimingParameter`            | 0x83        | 0xC3         |         |
+| `SecuredDataTransmission`          | 0x84        | 0xC4         |         |
+| `ControlDtcSetting`                | 0x85        | 0xC5         | ✓       |
+| `ResponseOnEvent`                  | 0x86        | 0xC6         |         |
+| `LinkControl`                      | 0x87        | 0xC7         |         |
 
 ## Integration
 
@@ -83,11 +85,11 @@ you need to keep before the buffer is reused.
 These services decode into typed \[`Request`\]/\[`Response`\] variants: `DiagnosticSessionControl`,
 `EcuReset`, `SecurityAccess`, `CommunicationControl`, `TesterPresent`, `ControlDtcSetting`,
 `ReadDataByIdentifier`, `WriteDataByIdentifier`, `ClearDiagnosticInfo`, `ReadDtcInfo`,
-`RoutineControl`, `RequestDownload`, `TransferData`, `RequestTransferExit`, `RequestFileTransfer`,
-and `NegativeResponse`.
+`RoutineControl`, `RequestDownload`, `RequestUpload`, `TransferData`, `RequestTransferExit`,
+`RequestFileTransfer`, and `NegativeResponse`.
 
 All other services enumerated in \[`UdsServiceType`\] (e.g. `Authentication`, `ReadMemoryByAddress`,
-`RequestUpload`, `ResponseOnEvent`) are not individually modeled. Frames for them decode into
+`ResponseOnEvent`) are not individually modeled. Frames for them decode into
 \[`Request::Other`\] / \[`Response::Other`\], carrying the service type and raw payload bytes for
 pass-through.
 

src/dtc/ext_data.rs

@@ -36,7 +36,7 @@ pub enum DtcExtDataRecordNumber {
 impl DtcExtDataRecordNumber {
     /// Create a new `DtcExtDataRecordNumber` from a raw byte, mapping it to the correct variant.
     #[must_use]
-    pub fn new(value: u8) -> Self {
+    pub const fn new(value: u8) -> Self {
         match value {
             0x00 | 0xF0..=0xFD => Self::IsoSaeReserved(value),
             0x01..=0x8F => Self::VehicleManufacturer(value),

src/dtc/snapshot.rs

@@ -23,7 +23,7 @@ impl DtcSnapshotRecordNumber {
     /// (`0x00`/`0xF0`), `All` (`0xFF`), or `Number`. Every byte is accepted (decoding is
     /// deliberately liberal); no value is rejected.
     #[must_use]
-    pub fn new(record_number: u8) -> Self {
+    pub const fn new(record_number: u8) -> Self {
         match record_number {
             0x00 | 0xF0 => Self::Reserved(record_number),
             0xFF => Self::All,

src/dtc/status.rs

@@ -204,13 +204,32 @@ pub struct DtcRecord {
 impl DtcRecord {
     /// Create a `DtcRecord` from its three component bytes.
     #[must_use]
-    pub fn new(high_byte: u8, middle_byte: u8, low_byte: u8) -> Self {
+    pub const fn new(high_byte: u8, middle_byte: u8, low_byte: u8) -> Self {
         Self {
             high_byte,
             middle_byte,
             low_byte,
         }
     }
+
+    /// The high byte, which ISO 14229-1 Annex D.1 uses to identify the system group
+    /// (powertrain, body, chassis, network).
+    #[must_use]
+    pub const fn high_byte(&self) -> u8 {
+        self.high_byte
+    }
+
+    /// The middle byte of the DTC number.
+    #[must_use]
+    pub const fn middle_byte(&self) -> u8 {
+        self.middle_byte
+    }
+
+    /// The low byte of the DTC number, which carries the failure type.
+    #[must_use]
+    pub const fn low_byte(&self) -> u8 {
+        self.low_byte
+    }
 }
 
 impl From<u32> for DtcRecord {
@@ -431,19 +450,21 @@ impl<'a> Decode<'a> for DtcSeverityMask {
     }
 }
 
-/// Indicates the number of the specific `DTCSnapshot` data record requested
-/// Setting to 0xFF will return all `DTCStoredDataRecords` at once
+/// Identifies which `DTCStoredDataRecord` is being requested.
+///
+/// Setting to `0xFF` will return all `DTCStoredDataRecords` at once.
 #[cfg_attr(feature = "serde", derive(serde::Deserialize, serde::Serialize))]
 #[cfg_attr(feature = "utoipa", derive(utoipa::ToSchema))]
 #[derive(Clone, Copy, Debug, Eq, PartialEq)]
 pub struct DtcStoredDataRecordNumber(u8);
 
-// create a constructor for DtcStoredDataRecordNumber
 impl DtcStoredDataRecordNumber {
+    /// Create a `DtcStoredDataRecordNumber` from a raw byte, rejecting the values ISO 14229-1
+    /// reserves.
     ///
     /// # Errors
-    /// Will return `Err(Error::ReservedForLegislativeUse()` if the record number == 0x00 or 0xF0
-    pub fn new(record_number: u8) -> Result<Self, Error> {
+    /// Returns [`Error::ReservedForLegislativeUse`] if the record number is `0x00` or `0xF0`.
+    pub const fn new(record_number: u8) -> Result<Self, Error> {
         if record_number == 0 || record_number == 0xF0 {
             return Err(Error::ReservedForLegislativeUse(record_number));
         }
@@ -551,6 +572,22 @@ mod encode_param_tests {
 mod dtc_status_tests {
     use super::*;
 
+    #[test]
+    fn dtc_record_exposes_its_three_wire_bytes() {
+        // A decoded DtcRecord has to be inspectable byte-wise: D.1 assigns meaning to the
+        // high byte (system group) separately from the middle and low bytes.
+        let record = DtcRecord::from(0x12_3456);
+        assert_eq!(record.high_byte(), 0x12);
+        assert_eq!(record.middle_byte(), 0x34);
+        assert_eq!(record.low_byte(), 0x56);
+    }
+
+    #[test]
+    fn dtc_record_byte_accessors_are_usable_in_const_context() {
+        const HIGH: u8 = CLEAR_ALL_DTCS.high_byte();
+        assert_eq!(HIGH, 0xFF);
+    }
+
     #[test]
     fn status_mask() {
         let status_mask = DtcStatusMask::TestFailed | DtcStatusMask::PendingDtc;