Struct Dbc 

pub struct Dbc { /* private fields */ }

Represents a complete DBC (CAN database) file.

A Dbc contains:

• An optional version string
• A list of nodes (ECUs)
• A collection of messages with their signals

Examples

use dbc_rs::Dbc;

let dbc_content = r#"VERSION "1.0"

BU_: ECM TCM

BO_ 256 EngineData : 8 ECM
 SG_ RPM : 0|16@0+ (0.25,0) [0|8000] "rpm" TCM
"#;

let dbc = Dbc::parse(dbc_content)?;
println!("Parsed {} messages", dbc.messages().len());

Implementations

impl Dbc

Decoding functionality for DBC structures

pub fn decode( &self, id: u32, payload: &[u8], is_extended: bool, ) -> Result<Vec<DecodedSignal<'_>, { MAX_SIGNALS_PER_MESSAGE }>>

Decode a CAN message payload using the message ID to find the corresponding message definition.

This is a high-performance method for decoding CAN messages in no_std environments. It finds the message by ID, then decodes all signals in the message from the payload bytes.

Arguments

• id - The raw CAN message ID (without extended flag)
• payload - The CAN message payload bytes (up to 64 bytes for CAN FD)
• is_extended - Whether this is an extended (29-bit) CAN ID

Returns

• Ok(Vec<DecodedSignal>) - A vector of decoded signals with name, value, and unit
• Err(Error) - If the message ID is not found, payload length doesn’t match DLC, or signal decoding fails

Examples

use dbc_rs::Dbc;

let dbc = Dbc::parse(r#"VERSION "1.0"

BU_: ECM

BO_ 256 Engine : 8 ECM
 SG_ RPM : 0|16@1+ (0.25,0) [0|8000] "rpm" *
"#)?;

// Decode a CAN message with RPM value of 2000 (raw: 8000 = 0x1F40)
let payload = [0x40, 0x1F, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00];
let decoded = dbc.decode(256, &payload, false)?; // false = standard CAN ID
assert_eq!(decoded.len(), 1);
assert_eq!(decoded[0].name, "RPM");
assert_eq!(decoded[0].value, 2000.0);
assert_eq!(decoded[0].unit, Some("rpm"));

High-performance CAN message decoding optimized for throughput.

Performance optimizations:

• O(1) or O(log n) message lookup via feature-flagged index
• Single-pass signal iteration with inline switch processing
• Stack-allocated switch value storage (no heap allocation)
• Message-level extended multiplexing check to skip per-signal lookups
• Inlined hot paths with early returns

impl Dbc

pub fn encode( &self, id: u32, signals: &[(&str, f64)], is_extended: bool, ) -> Result<Vec<u8, MAX_PAYLOAD_SIZE>>

Encode signal values into a CAN message payload.

This is the inverse of Dbc::decode(). It takes a list of signal names and their physical values, and produces a raw CAN message payload ready for transmission.

Arguments

• id - The raw CAN message ID (without extended flag)
• signals - Slice of (signal_name, physical_value) tuples to encode
• is_extended - Whether this is an extended (29-bit) CAN ID

Returns

• Ok(Vec<u8, 64>) - The encoded payload, sized according to message DLC
• Err(Error) - If message not found, signal not found, or value out of range

Examples

use dbc_rs::Dbc;

let dbc = Dbc::parse(r#"VERSION "1.0"

BU_: ECM

BO_ 256 Engine : 8 ECM
 SG_ RPM : 0|16@1+ (0.25,0) [0|8000] "rpm" *
 SG_ Temp : 16|8@1- (1,-40) [-40|215] "°C" *
"#)?;

// Encode RPM=2000 and Temp=50°C
let payload = dbc.encode(256, &[("RPM", 2000.0), ("Temp", 50.0)], false)?;

// The payload can now be transmitted over CAN
assert_eq!(payload.len(), 8);

Multiplexing

For multiplexed messages, include the multiplexer switch signal in the signal list along with the multiplexed signals you want to encode:

use dbc_rs::Dbc;

let dbc = Dbc::parse(r#"VERSION "1.0"

BU_: ECM

BO_ 300 Sensors : 8 ECM
 SG_ SensorID M : 0|8@1+ (1,0) [0|3] ""
 SG_ Temperature m0 : 8|16@1- (0.1,-40) [-40|125] "°C" *
 SG_ Pressure m1 : 8|16@1+ (0.01,0) [0|655.35] "kPa" *
"#)?;

// Encode temperature reading (SensorID=0)
let payload = dbc.encode(300, &[("SensorID", 0.0), ("Temperature", 25.0)], false)?;

impl Dbc

pub fn version(&self) -> Option<&Version>

Get the version of the DBC file

Examples

use dbc_rs::Dbc;

let dbc = Dbc::parse("VERSION \"1.0\"\n\nBU_: ECM\n\nBO_ 256 Engine : 8 ECM")?;
if let Some(version) = dbc.version() {
    // Version is available
    let _ = version.as_str();
}

pub fn bit_timing(&self) -> Option<&BitTiming>

Get the bit timing configuration

The BS_ section in DBC files specifies CAN bus timing parameters. Returns None if the BS_ section was empty or not present. Returns Some(&BitTiming) if timing parameters were specified.

Examples

use dbc_rs::Dbc;

let dbc = Dbc::parse("VERSION \"1.0\"\n\nBS_: 500000 : 1,2\n\nBU_: ECM\n\nBO_ 256 Engine : 8 ECM")?;
if let Some(bit_timing) = dbc.bit_timing() {
    println!("Baudrate: {:?}", bit_timing.baudrate());
}

pub fn nodes(&self) -> &Nodes

Get a reference to the nodes collection

Examples

use dbc_rs::Dbc;

let dbc = Dbc::parse("VERSION \"1.0\"\n\nBU_: ECM TCM\n\nBO_ 256 Engine : 8 ECM")?;
let nodes = dbc.nodes();
assert_eq!(nodes.len(), 2);
// Iterate over nodes
let mut iter = nodes.iter();
assert_eq!(iter.next(), Some("ECM"));
assert_eq!(iter.next(), Some("TCM"));
assert_eq!(iter.next(), None);

pub fn messages(&self) -> &Messages

Get a reference to the messages collection

Examples

use dbc_rs::Dbc;

let dbc = Dbc::parse("VERSION \"1.0\"\n\nBU_: ECM\n\nBO_ 256 Engine : 8 ECM")?;
let messages = dbc.messages();
assert_eq!(messages.len(), 1);
let message = messages.at(0).unwrap();
assert_eq!(message.name(), "Engine");
assert_eq!(message.id(), 256);

pub fn value_descriptions(&self) -> &ValueDescriptionsMap

Get value descriptions for a specific signal

Value descriptions map numeric signal values to human-readable text. Returns None if the signal has no value descriptions.

Global Value Descriptions: According to the Vector DBC specification, a message_id of -1 (0xFFFFFFFF) in a VAL_ statement means the value descriptions apply to all signals with that name in ANY message. This method will first check for a message-specific entry, then fall back to a global entry if one exists.

Examples

if let Some(value_descriptions) = dbc.value_descriptions_for_signal(100, "Gear") {
    if let Some(desc) = value_descriptions.get(0) {
        println!("Value 0 means: {}", desc);
    }
}

Get a reference to the value descriptions list

Examples

use dbc_rs::Dbc;

let dbc = Dbc::parse(r#"VERSION "1.0"

BU_: ECM

BO_ 100 Engine : 8 ECM
 SG_ Gear : 0|8@1+ (1,0) [0|5] "" *

VAL_ 100 Gear 0 "Park" 1 "Drive" ;"#)?;
let value_descriptions_list = dbc.value_descriptions();
assert_eq!(value_descriptions_list.len(), 1);

pub fn value_descriptions_for_signal( &self, message_id: u32, signal_name: &str, ) -> Option<&ValueDescriptions>

pub fn extended_multiplexing(&self) -> &[ExtendedMultiplexing]

Get all extended multiplexing entries

Returns a reference to all extended multiplexing (SG_MUL_VAL_) entries in the DBC file.

Examples

use dbc_rs::Dbc;

let dbc = Dbc::parse(r#"VERSION "1.0"

BU_: ECM

BO_ 500 MuxMessage : 8 ECM
 SG_ Mux1 M : 0|8@1+ (1,0) [0|255] ""
 SG_ Signal_A m0 : 16|16@1+ (0.1,0) [0|100] ""

SG_MUL_VAL_ 500 Signal_A Mux1 0-5 ;
"#)?;

let ext_mux = dbc.extended_multiplexing();
assert_eq!(ext_mux.len(), 1);

pub fn extended_multiplexing_for_message( &self, message_id: u32, ) -> impl Iterator<Item = &ExtendedMultiplexing> + '_

Get extended multiplexing entries for a specific message

Extended multiplexing (SG_MUL_VAL_) entries define which multiplexer switch values activate specific multiplexed signals. This method returns an iterator over references to extended multiplexing entries for the given message ID.

Performance

Returns an iterator of references (zero allocation) instead of cloning entries. This is optimized for the decode hot path where extended multiplexing is checked on every CAN frame.

Examples

use dbc_rs::Dbc;

let dbc = Dbc::parse(r#"VERSION "1.0"

BU_: ECM

BO_ 500 ComplexMux : 8 ECM
 SG_ Mux1 M : 0|8@1+ (1,0) [0|255] ""
 SG_ Signal_A m0 : 16|16@1+ (0.1,0) [0|100] ""

SG_MUL_VAL_ 500 Signal_A Mux1 0-5,10-15 ;
"#)?;
let extended: Vec<_> = dbc.extended_multiplexing_for_message(500).collect();
assert_eq!(extended.len(), 1);

pub fn comment(&self) -> Option<&str>

Returns the database-level comment from CM_ (general comment), if present.

This is the general comment for the entire DBC file, not associated with any specific node, message, or signal.

Examples

use dbc_rs::Dbc;

let dbc = Dbc::parse(r#"VERSION "1.0"

BU_: ECM

BO_ 256 Engine : 8 ECM

CM_ "CAN database for powertrain";"#)?;
assert_eq!(dbc.comment(), Some("CAN database for powertrain"));

pub fn node_comment(&self, node_name: &str) -> Option<&str>

Returns the comment for a specific node from CM_ BU_ entry, if present.

Examples

use dbc_rs::Dbc;

let dbc = Dbc::parse(r#"VERSION "1.0"

BU_: ECM

BO_ 256 Engine : 8 ECM

CM_ BU_ ECM "Engine Control Module";"#)?;
assert_eq!(dbc.node_comment("ECM"), Some("Engine Control Module"));

impl Dbc

pub fn attribute_definitions(&self) -> &AttributeDefinitionsMap

Get all attribute definitions (BA_DEF_ entries).

Examples

use dbc_rs::Dbc;

let dbc = Dbc::parse(r#"VERSION "1.0"

BU_: ECM

BO_ 256 Engine : 8 ECM

BA_DEF_ BO_ "GenMsgCycleTime" INT 0 10000;"#)?;
assert_eq!(dbc.attribute_definitions().len(), 1);

pub fn attribute_definition(&self, name: &str) -> Option<&AttributeDefinition>

Get an attribute definition by name.

pub fn attribute_defaults(&self) -> &AttributeDefaultsMap

Get all attribute defaults (BA_DEF_DEF_ entries).

pub fn attribute_default(&self, name: &str) -> Option<&AttributeValue>

Get the default value for an attribute by name.

pub fn attribute_values(&self) -> &AttributeValuesMap

Get all attribute values (BA_ entries).

pub fn network_attribute(&self, name: &str) -> Option<&AttributeValue>

Get a network-level attribute value by name.

Examples

use dbc_rs::Dbc;

let dbc = Dbc::parse(r#"VERSION "1.0"

BU_: ECM

BO_ 256 Engine : 8 ECM

BA_DEF_ "BusType" STRING;
BA_DEF_DEF_ "BusType" "";
BA_ "BusType" "CAN";"#)?;
if let Some(value) = dbc.network_attribute("BusType") {
    assert_eq!(value.as_string(), Some("CAN"));
}

pub fn node_attribute( &self, node_name: &str, attr_name: &str, ) -> Option<&AttributeValue>

Get a node attribute value by node name and attribute name.

pub fn message_attribute( &self, message_id: u32, attr_name: &str, ) -> Option<&AttributeValue>

Get a message attribute value by message ID and attribute name.

Examples

use dbc_rs::Dbc;

let dbc = Dbc::parse(r#"VERSION "1.0"

BU_: ECM

BO_ 256 Engine : 8 ECM

BA_DEF_ BO_ "GenMsgCycleTime" INT 0 10000;
BA_DEF_DEF_ "GenMsgCycleTime" 0;
BA_ "GenMsgCycleTime" BO_ 256 100;"#)?;
if let Some(value) = dbc.message_attribute(256, "GenMsgCycleTime") {
    assert_eq!(value.as_int(), Some(100));
}

pub fn signal_attribute( &self, message_id: u32, signal_name: &str, attr_name: &str, ) -> Option<&AttributeValue>

Get a signal attribute value by message ID, signal name, and attribute name.

pub fn network_attribute_or_default( &self, name: &str, ) -> Option<&AttributeValue>

Get a network attribute value with fallback to default.

First checks for a specific value assignment, then falls back to the attribute’s default value if no specific assignment exists.

pub fn node_attribute_or_default( &self, node_name: &str, attr_name: &str, ) -> Option<&AttributeValue>

Get a node attribute value with fallback to default.

pub fn message_attribute_or_default( &self, message_id: u32, attr_name: &str, ) -> Option<&AttributeValue>

Get a message attribute value with fallback to default.

pub fn signal_attribute_or_default( &self, message_id: u32, signal_name: &str, attr_name: &str, ) -> Option<&AttributeValue>

Get a signal attribute value with fallback to default.

impl Dbc

pub fn parse(data: &str) -> Result<Self>

Parse a DBC file from a string slice

Examples

use dbc_rs::Dbc;

let dbc_content = r#"VERSION "1.0"

BU_: ECM

BO_ 256 EngineData : 8 ECM
 SG_ RPM : 0|16@0+ (0.25,0) [0|8000] "rpm""#;

let dbc = Dbc::parse(dbc_content)?;
assert_eq!(dbc.messages().len(), 1);

pub fn parse_bytes(data: &[u8]) -> Result<Self>

Parse a DBC file from a byte slice

Examples

use dbc_rs::Dbc;

let dbc_bytes = b"VERSION \"1.0\"\n\nBU_: ECM\n\nBO_ 256 Engine : 8 ECM";
let dbc = Dbc::parse_bytes(dbc_bytes)?;
println!("Parsed {} messages", dbc.messages().len());

impl Dbc

pub fn from_file<P: AsRef<Path>>(path: P) -> Result<Self>

Load and parse a DBC file from disk.

Examples

use dbc_rs::Dbc;

let dbc = Dbc::from_file("path/to/file.dbc")?;
println!("Loaded {} messages", dbc.messages().len());

pub fn to_dbc_string(&self) -> String

Serialize this DBC to a DBC format string

Examples

use dbc_rs::Dbc;

let dbc = Dbc::parse("VERSION \"1.0\"\n\nBU_: ECM\n\nBO_ 256 Engine : 8 ECM")?;
let dbc_string = dbc.to_dbc_string();
// The string can be written to a file or used elsewhere
assert!(dbc_string.contains("VERSION"));

Trait Implementations

impl Clone for Dbc

fn clone(&self) -> Dbc

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for Dbc

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Display for Dbc

fn fmt(&self, f: &mut Formatter<'_>) -> FmtResult

Formats the value using the given formatter.

impl From<Dbc> for FastDbc

fn from(dbc: Dbc) -> Self

Converts to this type from the input type.