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//! //! Common types for ARINC 429 communication //! //! # Serialization/Deserialization //! //! When compiled with the `serde` feature, all types support serialization and deserialization. //! #![doc(html_root_url = "https://docs.rs/arinc_429/0.1.3")] #![cfg_attr(not(feature = "std"), no_std)] pub mod constants; #[cfg(not(feature = "std"))] mod fmt_provider { pub use core::fmt::*; } #[cfg(feature = "std")] mod fmt_provider { pub use std::fmt::*; } #[cfg(feature = "serde")] #[macro_use] extern crate serde; mod parity_error; pub use self::parity_error::ParityError; /// An ARINC 429 message /// /// The bits of a message are represented exactly as transmitted on the wires, with the least /// significant bit transmitted first. /// /// The label field is in the 8 least significant bits. Because the most significant digit of the /// label is transmitted first, the label field is in the reverse of the usual bit order. /// /// The parity bit is the most significant bit. /// /// # Conversions /// /// The `u32::from(Message)` and `Message::from(u32)` `From` implementations copy bits with no /// changes. /// /// Some ARINC 429 adapters use a different representation, where the bits of the label field are /// reversed from their on-wire representation. The methods `Message::from_bits_label_swapped()` and /// `Message::bits_label_swapped()` implement this conversion. /// /// Conversions never panic. /// /// # Examples /// /// Create a message /// /// ``` /// # use arinc_429::Message; /// let message = Message::from(0x10000056); /// assert_eq!(0x10000056, u32::from(message)); /// ``` /// /// Label bit swapping /// /// ``` /// # use arinc_429::Message; /// let message = Message::from_bits_label_swapped(0x10000056); /// assert_eq!(0x1000006a, u32::from(message)); /// ``` /// #[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash, Default)] #[cfg_attr(feature = "serde", derive(Serialize, Deserialize))] pub struct Message(u32); impl Message { /// Returns the bits that represent this message pub fn bits(&self) -> u32 { self.0 } /// Returns the bits of this message, but /// with the order of the 8 label bits reversed. pub fn bits_label_swapped(&self) -> u32 { let bits = self.bits(); Self::swap_label_bits(bits) } /// Creates a message from a message representation with the 8 label bits /// reversed. The returned Msg429 will be represented as transmitted on the wires. pub fn from_bits_label_swapped(bits: u32) -> Self { let bits = Self::swap_label_bits(bits); Message(bits) } /// Checks the parity of this message, and returns an error if the parity is not odd /// /// # Examples /// /// ``` /// # use arinc_429::Message; /// assert!(Message::from(0x0).check_parity().is_err()); /// assert!(Message::from(0xf03ccccc).check_parity().is_err()); /// assert!(Message::from(0x1).check_parity().is_ok()); /// assert!(Message::from(0xf13ccccc).check_parity().is_ok()); /// ``` /// pub fn check_parity(&self) -> Result<(), ParityError> { // Should have an odd number of ones if self.0.count_ones() % 2 == 1 { Ok(()) } else { let parity = (self.0 >> 31) as u8; let expected = parity ^ 1; Err(ParityError::new(expected, parity)) } } /// Calculates the parity of this message and returns a new message with the parity bit (31) to /// the correct value /// /// # Examples /// /// ``` /// # use arinc_429::Message; /// // Create a message with incorrect (even) parity /// let message = Message::from(0x22443300); /// assert_eq!(message.update_parity().bits(), 0xa2443300); /// ``` /// /// ``` /// # use arinc_429::Message; /// // Create a message with correct (odd) parity /// let message = Message::from(0x22443301); /// // Message should not change /// assert_eq!(message.update_parity(), message); /// ``` /// pub fn update_parity(&self) -> Message { match self.check_parity() { Ok(_) => self.clone(), Err(_) => { // Flip parity bit Message(self.0 ^ 1 << 31) } } } /// Reverses the order of the 8 least significant bits of a value. /// Returns bits 32-9 unmodified, but with bits 1-8 reversed. fn swap_label_bits(bits: u32) -> u32 { let label = bits & 0xff; let new_label = ((label & 0x1) << 7) | ((label & 0x2) << 5) | ((label & 0x4) << 3) | ((label & 0x8) << 1) | ((label & 0x10) >> 1) | ((label & 0x20) >> 3) | ((label & 0x40) >> 5) | ((label & 0x80) >> 7); (bits & 0xffffff00) | new_label } } impl From<u32> for Message { /// Creates a message from bits as transmitted, with no modifications fn from(bits: u32) -> Self { Message(bits) } } impl From<Message> for u32 { /// Converts a message into bits, with no modifications fn from(Message(bits): Message) -> u32 { bits } } mod msg_fmt { use super::Message; use super::fmt_provider::{Debug, Formatter, Result}; impl Debug for Message { fn fmt(&self, f: &mut Formatter) -> Result { write!(f, "Msg429({:#x})", self.0) } } } /// ARINC 429 communication speeds #[derive(Debug, Copy, Clone, PartialEq, Eq, Hash)] #[cfg_attr(feature = "serde", derive(Serialize, Deserialize))] #[cfg_attr(feature = "serde", serde(rename = "speed"))] #[cfg_attr(feature = "serde", serde(rename_all = "lowercase"))] pub enum Speed { /// High speed, 100 kbps High, /// Low speed, 12.5 kbps Low, }