modular-bitfield 0.11.2

// One downside of the way we have implemented enum support so far is that it
// makes it impossible to see from the definition of a bitfield struct how the
// bits are being laid out. In something like the following bitfield, all we
// know from this code is that the total size is a multiple of 8 bits. Maybe
// trigger_mode is 11 bits and delivery_mode is 1 bit. This may tend to make
// maintenance problematic when the types involved are defined across different
// modules or even different crates.
//
//     #[bitfield]
//     pub struct RedirectionTableEntry {
//         trigger_mode: TriggerMode,
//         delivery_mode: DeliveryMode,
//         reserved: B4,
//     }
//
// Introduce an optional #[bits = N] attribute to serve as compile-time checked
// documentation of field size. Ensure that this attribute is entirely optional,
// meaning that the code behaves the same whether or not you write it, but if
// the user does provide the attribute then the program must not compile if
// their value is wrong.

use modular_bitfield::prelude::*;

#[bitfield]
pub struct RedirectionTableEntry {
    #[bits = 1]
    trigger_mode: TriggerMode,
    #[bits = 3]
    delivery_mode: DeliveryMode,
    reserved: B4,
}

#[derive(BitfieldSpecifier, Debug)]
pub enum TriggerMode {
    Edge = 0,
    Level = 1,
}

#[derive(BitfieldSpecifier, Debug)]
pub enum DeliveryMode {
    Fixed = 0b000,
    Lowest = 0b001,
    SMI = 0b010,
    RemoteRead = 0b011,
    NMI = 0b100,
    Init = 0b101,
    Startup = 0b110,
    External = 0b111,
}

fn main() {}