Keyboard

This is implemented in keyboard

The keyboard driver is simple, and uses the legacy PS/2 interface at 0x60 and 0x64 ports, its implemented alongside the mouse driver in the same file.

The driver provide events broadcasts to all listeners using blinkcast. These listeners are mostly processes reading from the /devices/keyboard file (see keyboard reader).

#![allow(unused)]
fn main() {
pub struct Key {
    pub pressed: bool,
    // the state of the modifiers at the time of the fetch
    pub modifiers: u8,
    pub key_type: KeyType,
}
}

Where KeyType is an enum containing all keys from a US mapping.

The keyboard user can then use this as the origin, and map it to any other key depending on the layout they want.

Currently, we use the US layout to get the character of a key using the function Key::virtual_key (used in the kernel and userspace).

The modifiers field is a bitflags from modifier, so use these constants to check if a specific modifier is on.

There are 2 types of modifiers:

• Held modifiers: SHIFT, CTRL, ALT
• Toggled modifiers: CAPSLOCK, NUMLOCK, SCROLLLOCK

Keyboard reader

The keyboard driver provide a way to get a blinkcast reader using get_keyboard_reader, where the user can read keyboard events without blocking anytime they want.

The console and userspace processes use this reader to read keyboard events.

For userspace processes, they can read the keyboard events through the virtual device at /devices/keyboard.

A process can open a file descriptor to this device and read from it to get keyboard events.

The file descriptor will hold a blinkcast reader to the keyboard driver, then each process can read events without blocking.

The user can open the file and read the content, but since we are performing some encoding, its better to use the library emerald_runtime which provide easy way to read the events.

Example:

#![allow(unused)]
fn main() {
use emerald_runtime::keyboard::Keyboard;

let mut keyboard = Keyboard::new();

if let Some(key) = keyboard.get_key_event() {
    println!("Key: {:?}", key);
}
// or
for key in keyboard.iter_keys() {
    println!("Key: {:?}", key);
}
}