Struct MessageDescriptor 

pub struct MessageDescriptor<'a> {
    pub id: u32,
    pub name: &'a str,
    pub crc_extra: u8,
    pub fields: &'a [FieldDescriptor<'a>],
}

The shape of one message: what a sender fills in and a receiver reads back.

Fields are held in wire order, which for the base fields is largest type first. A descriptor written by hand must already be in that order; MessageDescriptorBuilder does the reordering for a definition written the way a dialect reads.

Fields

id: u32

The message id on the wire.

name: &'a str

The message name, such as "HEARTBEAT".

crc_extra: u8

The CRC_EXTRA seed folded into the checksum of a frame carrying this message.

fields: &'a [FieldDescriptor<'a>]

The fields in wire order: the base fields largest first, then any extensions.

Implementations

impl<'a> MessageDescriptor<'a>

pub fn wire_len(&self) -> usize

Returns the full length of the message on the wire, extensions included.

Returns

The sum of every field’s size, in bytes.

pub fn base_len(&self) -> usize

Returns the length of the message’s base fields, in bytes.

This is what a peer that predates the extensions expects, and the length the CRC_EXTRA seed describes.

Returns

The sum of the base fields’ sizes.

pub fn field(&self, name: &str) -> Option<&'a FieldDescriptor<'a>>

Looks a field up by name.

Arguments

• name - the field name to find.

Returns

The field, or None if the message has no field of that name.

pub fn offset_of(&self, name: &str) -> Option<usize>

Returns the byte offset of a field within the payload.

Arguments

• name - the field name to locate.

Returns

The offset, or None if the message has no field of that name.

pub fn derived_crc_extra(&self) -> u8

Derives the CRC_EXTRA seed from this descriptor’s base fields.

A descriptor whose crc_extra differs from this has a field wrong: a mistyped field, a wrong array length, or fields out of wire order.

Returns

The seed the fields imply.

Examples

use pamoja_mavlink::dialect::descriptor;

let heartbeat = descriptor(0).expect("HEARTBEAT is in the common dialect");
assert_eq!(heartbeat.derived_crc_extra(), heartbeat.crc_extra);

Trait Implementations

impl<'a> Clone for MessageDescriptor<'a>

fn clone(&self) -> MessageDescriptor<'a>

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl<'a> Copy for MessageDescriptor<'a>

impl<'a> Debug for MessageDescriptor<'a>

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

Formats the value using the given formatter.

impl<'a> Eq for MessageDescriptor<'a>

impl<'a> PartialEq for MessageDescriptor<'a>

fn eq(&self, other: &MessageDescriptor<'a>) -> bool

Tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Rhs) -> bool

Tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl<'a> StructuralPartialEq for MessageDescriptor<'a>