bus.rs

//! In order to be able to connect to the motherboard, auxiliary components must implement the [`Bus`] trait.
//!
//! This trait describes how the component handles NAME, METADATA, READ, WRITE and RESET requests from the motherboard.

/// Bus of an auxiliary component.
/// All components must implement this type in order to be connected to the motherboard.
pub trait Bus {
    /// Get the component's generic name.
    /// Any name longer than 32 bytes will be cut from the right to the maximum length not exceeding 32 bytes in size.
    fn name(&self) -> &'static str;

    /// Get the component's metadata.
    /// See the documentation for the metadata's structure.
    fn metadata(&self) -> [u32; 8];

    /// Answer a READ request from the bus.
    /// The provided address is guaranteed to be aligned (multiple of 4) and strictly lower than the provided size.
    /// May raise an exception by assigning a non-zero exception code and data to the provided reference.
    fn read(&mut self, addr: u32, ex: &mut u16) -> u32;

    /// Answer a WRITE request from the bus.
    /// The provided address is guaranteed to be aligned (multiple of 4) and strictly lower than the provided size.
    /// May raise ane xception by assigning a non-zero exception code and data to the provided reference.
    fn write(&mut self, addr: u32, word: u32, ex: &mut u16);

    /// Handle a RESET signal sent by the motherboard.
    /// All volatile data from the component must be reset.
    fn reset(&mut self);
}