Generate message length and cycle time consts from DBC attributes

src/lib.rs

@@ -24,7 +24,9 @@ use can_dbc::MultiplexIndicator::{
     MultiplexedSignal, Multiplexor, MultiplexorAndMultiplexedSignal, Plain,
 };
 use can_dbc::ValueType::Signed;
-use can_dbc::{Dbc, Message, MessageId, Signal, Transmitter, ValDescription, ValueDescription};
+use can_dbc::{
+    AttributeValue, Dbc, Message, MessageId, Signal, Transmitter, ValDescription, ValueDescription,
+};
 use heck::ToSnakeCase;
 use quote::ToTokens;
 use typed_builder::TypedBuilder;
@@ -134,6 +136,13 @@ impl Config<'_> {
         writeln!(w, "use bitvec::prelude::*;")?;
         writeln!(w, "#[allow(unused_imports)]")?;
         writeln!(w, "use embedded_can::{{Id, StandardId, ExtendedId}};")?;
+        if get_relevant_messages(&dbc).any(|m| {
+            message_attr(&dbc, m.id, "GenMsgCycleTime")
+                .and_then(attr_value_u64)
+                .is_some()
+        }) {
+            writeln!(w, "use core::time::Duration;")?;
+        }
 
         self.impl_arbitrary.fmt_cfg(&mut w, |w| {
             writeln!(w, "use arbitrary::{{Arbitrary, Unstructured}};")
@@ -278,6 +287,11 @@ impl Config<'_> {
             )?;
             writeln!(w)?;
 
+            writeln!(w, "pub const MESSAGE_SIZE: usize = {};", msg.size)?;
+            writeln!(w)?;
+
+            Self::render_cycle_time(&mut w, msg, dbc)?;
+
             for signal in &msg.signals {
                 let typ = ValType::from_signal(signal);
                 if typ != ValType::Bool {
@@ -414,6 +428,23 @@ impl Config<'_> {
         Ok(())
     }
 
+    /// Emit the cycle time as a constant for messages that have an assigned
+    /// `GenMsgCycleTime` (`BA_`) attribute.
+    fn render_cycle_time(w: &mut impl Write, msg: &Message, dbc: &Dbc) -> Result<()> {
+        let Some(ms) = message_attr(dbc, msg.id, "GenMsgCycleTime").and_then(attr_value_u64) else {
+            return Ok(());
+        };
+        writeln!(
+            w,
+            "/// Message cycle time (from the `GenMsgCycleTime` attribute)."
+        )?;
+        writeln!(
+            w,
+            "pub const MESSAGE_CYCLE_TIME: Duration = Duration::from_millis({ms});"
+        )?;
+        Ok(())
+    }
+
     fn render_signal(
         &self,
         w: &mut impl Write,
@@ -1322,6 +1353,23 @@ fn message_ignored(message: &Message) -> bool {
     message.name == "VECTOR__INDEPENDENT_SIG_MSG"
 }
 
+/// Look up an assigned message-level (`BO_`) attribute value.
+fn message_attr<'a>(dbc: &'a Dbc, id: MessageId, name: &str) -> Option<&'a AttributeValue> {
+    dbc.attribute_values_message
+        .iter()
+        .find(|a| a.message_id == id && a.name == name)
+        .map(|a| &a.value)
+}
+
+/// Interpret an attribute value as a non-negative integer, if it is one.
+fn attr_value_u64(value: &AttributeValue) -> Option<u64> {
+    match value {
+        AttributeValue::Uint(v) => Some(*v),
+        AttributeValue::Int(v) => u64::try_from(*v).ok(),
+        AttributeValue::Double(_) | AttributeValue::String(_) => None,
+    }
+}
+
 impl Config<'_> {
     /// Generate Rust structs matching DBC input description and return as String
     pub fn generate(self) -> Result<String> {

testing/can-messages/tests/all.rs

@@ -195,3 +195,12 @@ fn test_extended_id() {
         Id::Extended(ExtendedId::new(0x1234).unwrap())
     );
 }
+
+#[test]
+fn test_message_size() {
+    assert_eq!(Foo::MESSAGE_SIZE, 4);
+    assert_eq!(MsgExtendedId::MESSAGE_SIZE, 8);
+
+    let m = Foo::new(0.0, 0.0).unwrap();
+    assert_eq!(m.raw().len(), Foo::MESSAGE_SIZE);
+}

tests-snapshots/canpy/DBC_template.snap.rs

@@ -76,6 +76,7 @@ impl CanMultiplexed {
     pub const MESSAGE_ID: embedded_can::Id = Id::Extended(unsafe {
         ExtendedId::new_unchecked(0x10e1)
     });
+    pub const MESSAGE_SIZE: usize = 2;
     pub const VALUE1_MIN: u8 = 0_u8;
     pub const VALUE1_MAX: u8 = 0_u8;
     pub const VALUE0_MIN: u8 = 0_u8;
@@ -454,6 +455,7 @@ impl CanMessage {
     pub const MESSAGE_ID: embedded_can::Id = Id::Standard(unsafe {
         StandardId::new_unchecked(0x4d2)
     });
+    pub const MESSAGE_SIZE: usize = 8;
     pub const SIGNAL1_MIN: u64 = 0_u64;
     pub const SIGNAL1_MAX: u64 = 100_u64;
     pub const SIGNAL0_MIN: i32 = 0_i32;

tests-snapshots/dbc-cantools/BU_BO_REL_.snap.rs

@@ -67,6 +67,7 @@ impl Control {
     pub const MESSAGE_ID: embedded_can::Id = Id::Standard(unsafe {
         StandardId::new_unchecked(0x1)
     });
+    pub const MESSAGE_SIZE: usize = 7;
     pub const STATE_MIN: u8 = 0_u8;
     pub const STATE_MAX: u8 = 100_u8;
     /// Construct new CONTROL from values

tests-snapshots/dbc-cantools/BU_BO_REL_Message.snap.rs

@@ -67,6 +67,7 @@ impl Message1 {
     pub const MESSAGE_ID: embedded_can::Id = Id::Standard(unsafe {
         StandardId::new_unchecked(0x1)
     });
+    pub const MESSAGE_SIZE: usize = 7;
     pub const SIGNAL_1_MIN: u8 = 0_u8;
     pub const SIGNAL_1_MAX: u8 = 100_u8;
     /// Construct new message_1 from values

tests-snapshots/dbc-cantools/CamelCaseEmpty.snap.rs

@@ -67,6 +67,7 @@ impl Message1 {
     pub const MESSAGE_ID: embedded_can::Id = Id::Standard(unsafe {
         StandardId::new_unchecked(0x400)
     });
+    pub const MESSAGE_SIZE: usize = 5;
     /// Construct new Message1 from values
     pub fn new() -> Result<Self, CanError> {
         let res = Self { raw: [0u8; 5] };

tests-snapshots/dbc-cantools/abs.snap.rs

@@ -118,6 +118,7 @@ impl Bremse33 {
     pub const MESSAGE_ID: embedded_can::Id = Id::Standard(unsafe {
         StandardId::new_unchecked(0x343)
     });
+    pub const MESSAGE_SIZE: usize = 8;
     pub const WHLSPEED_FL_MIN: f32 = 0_f32;
     pub const WHLSPEED_FL_MAX: f32 = 100_f32;
     pub const WHLSPEED_FR_MIN: f32 = 0_f32;
@@ -369,6 +370,7 @@ impl Bremse10 {
     pub const MESSAGE_ID: embedded_can::Id = Id::Standard(unsafe {
         StandardId::new_unchecked(0x140)
     });
+    pub const MESSAGE_SIZE: usize = 8;
     /// Construct new BREMSE_10 from values
     pub fn new() -> Result<Self, CanError> {
         let res = Self { raw: [0u8; 8] };
@@ -439,6 +441,7 @@ impl Bremse11 {
     pub const MESSAGE_ID: embedded_can::Id = Id::Standard(unsafe {
         StandardId::new_unchecked(0x141)
     });
+    pub const MESSAGE_SIZE: usize = 8;
     /// Construct new BREMSE_11 from values
     pub fn new() -> Result<Self, CanError> {
         let res = Self { raw: [0u8; 8] };
@@ -509,6 +512,7 @@ impl Bremse12 {
     pub const MESSAGE_ID: embedded_can::Id = Id::Standard(unsafe {
         StandardId::new_unchecked(0x142)
     });
+    pub const MESSAGE_SIZE: usize = 8;
     /// Construct new BREMSE_12 from values
     pub fn new() -> Result<Self, CanError> {
         let res = Self { raw: [0u8; 8] };
@@ -579,6 +583,7 @@ impl Bremse13 {
     pub const MESSAGE_ID: embedded_can::Id = Id::Standard(unsafe {
         StandardId::new_unchecked(0x143)
     });
+    pub const MESSAGE_SIZE: usize = 8;
     /// Construct new BREMSE_13 from values
     pub fn new() -> Result<Self, CanError> {
         let res = Self { raw: [0u8; 8] };
@@ -649,6 +654,7 @@ impl DrsRxId0 {
     pub const MESSAGE_ID: embedded_can::Id = Id::Standard(unsafe {
         StandardId::new_unchecked(0x75)
     });
+    pub const MESSAGE_SIZE: usize = 8;
     /// Construct new DRS_RX_ID0 from values
     pub fn new() -> Result<Self, CanError> {
         let res = Self { raw: [0u8; 8] };
@@ -719,6 +725,7 @@ impl Mm510Tx1 {
     pub const MESSAGE_ID: embedded_can::Id = Id::Standard(unsafe {
         StandardId::new_unchecked(0x70)
     });
+    pub const MESSAGE_SIZE: usize = 8;
     pub const YAW_RATE_MIN: f32 = -163.84_f32;
     pub const YAW_RATE_MAX: f32 = 163.83_f32;
     pub const AY1_MIN: f32 = -4.1768_f32;
@@ -877,6 +884,7 @@ impl Mm510Tx2 {
     pub const MESSAGE_ID: embedded_can::Id = Id::Standard(unsafe {
         StandardId::new_unchecked(0x80)
     });
+    pub const MESSAGE_SIZE: usize = 8;
     pub const ROLL_RATE_MIN: f32 = -163.84_f32;
     pub const ROLL_RATE_MAX: f32 = 163.835_f32;
     pub const AX1_MIN: f32 = -4.1768_f32;
@@ -1035,6 +1043,7 @@ impl Mm510Tx3 {
     pub const MESSAGE_ID: embedded_can::Id = Id::Standard(unsafe {
         StandardId::new_unchecked(0x576)
     });
+    pub const MESSAGE_SIZE: usize = 8;
     pub const AZ_MIN: f32 = -4.1768_f32;
     pub const AZ_MAX: f32 = 4.1765_f32;
     /// Construct new MM5_10_TX3 from values
@@ -1149,6 +1158,7 @@ impl Bremse2 {
     pub const MESSAGE_ID: embedded_can::Id = Id::Standard(unsafe {
         StandardId::new_unchecked(0x24a)
     });
+    pub const MESSAGE_SIZE: usize = 8;
     pub const WHLSPEED_FL_BREMSE2_MIN: f32 = 0_f32;
     pub const WHLSPEED_FL_BREMSE2_MAX: f32 = 100_f32;
     pub const WHLSPEED_FR_BREMSE2_MIN: f32 = 0_f32;
@@ -1399,6 +1409,7 @@ impl AbsSwitch {
     pub const MESSAGE_ID: embedded_can::Id = Id::Standard(unsafe {
         StandardId::new_unchecked(0x24c)
     });
+    pub const MESSAGE_SIZE: usize = 8;
     pub const ABS_SWITCHPOSITION_MIN: u8 = 0_u8;
     pub const ABS_SWITCHPOSITION_MAX: u8 = 11_u8;
     /// Construct new ABS_Switch from values
@@ -1516,6 +1527,7 @@ impl Bremse30 {
     pub const MESSAGE_ID: embedded_can::Id = Id::Standard(unsafe {
         StandardId::new_unchecked(0x340)
     });
+    pub const MESSAGE_SIZE: usize = 8;
     /// Construct new BREMSE_30 from values
     pub fn new() -> Result<Self, CanError> {
         let res = Self { raw: [0u8; 8] };
@@ -1586,6 +1598,7 @@ impl Bremse31 {
     pub const MESSAGE_ID: embedded_can::Id = Id::Standard(unsafe {
         StandardId::new_unchecked(0x341)
     });
+    pub const MESSAGE_SIZE: usize = 8;
     pub const IDLE_TIME_MIN: u16 = 0_u16;
     pub const IDLE_TIME_MAX: u16 = 0_u16;
     /// Construct new BREMSE_31 from values
@@ -1701,6 +1714,7 @@ impl Bremse32 {
     pub const MESSAGE_ID: embedded_can::Id = Id::Standard(unsafe {
         StandardId::new_unchecked(0x342)
     });
+    pub const MESSAGE_SIZE: usize = 8;
     pub const ACC_FA_MIN: f32 = 0_f32;
     pub const ACC_FA_MAX: f32 = 10_f32;
     pub const ACC_RA_MIN: f32 = 0_f32;
@@ -2086,6 +2100,7 @@ impl Bremse51 {
     pub const MESSAGE_ID: embedded_can::Id = Id::Standard(unsafe {
         StandardId::new_unchecked(0x541)
     });
+    pub const MESSAGE_SIZE: usize = 8;
     pub const AX1_ABS_INT_MIN: f32 = -4.1768_f32;
     pub const AX1_ABS_INT_MAX: f32 = 4.1736697_f32;
     pub const AY1_ABS_INT_MIN: f32 = -4.1768_f32;
@@ -2391,6 +2406,7 @@ impl Bremse52 {
     pub const MESSAGE_ID: embedded_can::Id = Id::Standard(unsafe {
         StandardId::new_unchecked(0x542)
     });
+    pub const MESSAGE_SIZE: usize = 8;
     pub const MPLX_SW_INFO_MIN: u8 = 0_u8;
     pub const MPLX_SW_INFO_MAX: u8 = 255_u8;
     pub const SW_VERSION_HIGH_UPPER_MIN: u8 = 0_u8;
@@ -4522,6 +4538,7 @@ impl Bremse50 {
     pub const MESSAGE_ID: embedded_can::Id = Id::Standard(unsafe {
         StandardId::new_unchecked(0x560)
     });
+    pub const MESSAGE_SIZE: usize = 8;
     pub const BRAKE_BAL_AT50_MIN: f32 = 0_f32;
     pub const BRAKE_BAL_AT50_MAX: f32 = 100_f32;
     pub const BRAKE_BAL_AT50_ADVICE_MIN: u8 = 0_u8;
@@ -4779,6 +4796,7 @@ impl Bremse53 {
     pub const MESSAGE_ID: embedded_can::Id = Id::Standard(unsafe {
         StandardId::new_unchecked(0x5c0)
     });
+    pub const MESSAGE_SIZE: usize = 8;
     pub const SWITCH_POSITION_MIN: u8 = 1_u8;
     pub const SWITCH_POSITION_MAX: u8 = 12_u8;
     pub const P_FA_MIN: f32 = -42.5_f32;

tests-snapshots/dbc-cantools/add_two_dbc_files_1.snap.rs

@@ -70,6 +70,7 @@ impl M1 {
     pub const MESSAGE_ID: embedded_can::Id = Id::Standard(unsafe {
         StandardId::new_unchecked(0x1)
     });
+    pub const MESSAGE_SIZE: usize = 8;
     /// Construct new M1 from values
     pub fn new() -> Result<Self, CanError> {
         let res = Self { raw: [0u8; 8] };
@@ -140,6 +141,7 @@ impl M2 {
     pub const MESSAGE_ID: embedded_can::Id = Id::Standard(unsafe {
         StandardId::new_unchecked(0x2)
     });
+    pub const MESSAGE_SIZE: usize = 8;
     /// Construct new M2 from values
     pub fn new() -> Result<Self, CanError> {
         let res = Self { raw: [0u8; 8] };

tests-snapshots/dbc-cantools/add_two_dbc_files_2.snap.rs

@@ -67,6 +67,7 @@ impl M1 {
     pub const MESSAGE_ID: embedded_can::Id = Id::Standard(unsafe {
         StandardId::new_unchecked(0x2)
     });
+    pub const MESSAGE_SIZE: usize = 8;
     /// Construct new M1 from values
     pub fn new() -> Result<Self, CanError> {
         let res = Self { raw: [0u8; 8] };

tests-snapshots/dbc-cantools/attribute_Event.snap.rs

@@ -10,6 +10,7 @@ use core::ops::BitOr;
 use bitvec::prelude::*;
 #[allow(unused_imports)]
 use embedded_can::{Id, StandardId, ExtendedId};
+use core::time::Duration;
 /// All messages
 #[allow(
     clippy::absurd_extreme_comparisons,
@@ -69,6 +70,9 @@ impl Inv2EventMsg1 {
     pub const MESSAGE_ID: embedded_can::Id = Id::Standard(unsafe {
         StandardId::new_unchecked(0x4d2)
     });
+    pub const MESSAGE_SIZE: usize = 8;
+    /// Message cycle time (from the `GenMsgCycleTime` attribute).
+    pub const MESSAGE_CYCLE_TIME: Duration = Duration::from_millis(0);
     pub const THE_SIGNAL_MIN: i8 = 0_i8;
     pub const THE_SIGNAL_MAX: i8 = 0_i8;
     /// Construct new INV2EventMsg1 from values

tests-snapshots/dbc-cantools/attributes.snap.rs

@@ -10,6 +10,7 @@ use core::ops::BitOr;
 use bitvec::prelude::*;
 #[allow(unused_imports)]
 use embedded_can::{Id, StandardId, ExtendedId};
+use core::time::Duration;
 /// All messages
 #[allow(
     clippy::absurd_extreme_comparisons,
@@ -73,6 +74,9 @@ impl TheMessage {
     pub const MESSAGE_ID: embedded_can::Id = Id::Extended(unsafe {
         ExtendedId::new_unchecked(0x39)
     });
+    pub const MESSAGE_SIZE: usize = 8;
+    /// Message cycle time (from the `GenMsgCycleTime` attribute).
+    pub const MESSAGE_CYCLE_TIME: Duration = Duration::from_millis(1000);
     pub const THE_SIGNAL_MIN: i8 = 0_i8;
     pub const THE_SIGNAL_MAX: i8 = 0_i8;
     /// Construct new TheMessage from values
@@ -189,6 +193,7 @@ impl TheOtherMessage {
     pub const MESSAGE_ID: embedded_can::Id = Id::Standard(unsafe {
         StandardId::new_unchecked(0x2a)
     });
+    pub const MESSAGE_SIZE: usize = 8;
     pub const THE_SIGNAL_MIN: i8 = 0_i8;
     pub const THE_SIGNAL_MAX: i8 = 0_i8;
     /// Construct new TheOtherMessage from values

tests-snapshots/dbc-cantools/attributes_relation.snap.rs

@@ -10,6 +10,7 @@ use core::ops::BitOr;
 use bitvec::prelude::*;
 #[allow(unused_imports)]
 use embedded_can::{Id, StandardId, ExtendedId};
+use core::time::Duration;
 /// All messages
 #[allow(
     clippy::absurd_extreme_comparisons,
@@ -70,6 +71,9 @@ impl Message2 {
     pub const MESSAGE_ID: embedded_can::Id = Id::Standard(unsafe {
         StandardId::new_unchecked(0x53)
     });
+    pub const MESSAGE_SIZE: usize = 8;
+    /// Message cycle time (from the `GenMsgCycleTime` attribute).
+    pub const MESSAGE_CYCLE_TIME: Duration = Duration::from_millis(50);
     pub const SIGNAL_2_MIN: i8 = 0_i8;
     pub const SIGNAL_2_MAX: i8 = 0_i8;
     /// Construct new Message_2 from values
@@ -187,6 +191,7 @@ impl Message1 {
     pub const MESSAGE_ID: embedded_can::Id = Id::Standard(unsafe {
         StandardId::new_unchecked(0x52)
     });
+    pub const MESSAGE_SIZE: usize = 8;
     pub const SIGNAL_1_MIN: i8 = 0_i8;
     pub const SIGNAL_1_MAX: i8 = 0_i8;
     /// Construct new Message_1 from values