use crate::*;


pub trait DeviceBus {
    /// Attempt to wake the system.
    fn wake(&mut self) -> bool;
    /// Get a device by slot number.
    fn get_device(&mut self, slot: u8) -> Option<&mut dyn Device>;
    // Read from a device port.
    fn read(&mut self, port: u8) -> u8 {
        match self.get_device(port >> 4) {
            Some(device) => device.read(port & 0xF),
            None => 0,
        }
    }
    // Write to a device port.
    fn write(&mut self, port: u8, value: u8) -> Option<Signal> {
        match self.get_device(port >> 4) {
            Some(device) => device.write(port & 0xF, value),
            None => None,
        }
    }
    /// Reset all connected devices.
    fn reset(&mut self) {
        for slot in 0..16 {
            if let Some(device) = self.get_device(slot) {
                device.reset();
            }
        }
    }
}


pub trait Device {
    fn read(&mut self, port: u8) -> u8;
    fn write(&mut self, port: u8, value: u8) -> Option<Signal>;
    /// Return and clear the wake flag for this device.
    fn wake(&mut self) -> bool;
    /// Reset device to the initial state.
    fn reset(&mut self);
}

impl Device for () {
    fn read(&mut self, _: u8) -> u8 { 0 }
    fn write(&mut self, _: u8, _: u8) -> Option<Signal> { None }
    fn wake(&mut self) -> bool { false }
    fn reset(&mut self) { }
}