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Hardware Interrupts: Update pc-keyboard crate to v0.5.0

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Philipp Oppermann
2020-02-26 12:17:35 +01:00
parent acea700708
commit fb920af5dc
1 changed files with 16 additions and 10 deletions
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26
blog/content/second-edition/posts/07-hardware-interrupts/index.md
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@@ -656,13 +656,13 @@ Now we can write numbers:
Translating the other keys works in the same way. Fortunately there is a crate named [`pc-keyboard`] for translating scancodes of scancode sets 1 and 2, so we don't have to implement this ourselves. To use the crate, we add it to our `Cargo.toml` and import it in our `lib.rs`:
[`pc-keyboard`]: https://docs.rs/pc-keyboard/0.3.1/pc_keyboard/
[`pc-keyboard`]: https://docs.rs/pc-keyboard/0.5.0/pc_keyboard/
```toml
# in Cargo.toml
[dependencies]
pc-keyboard = "0.3.1"
pc-keyboard = "0.5.0"
```
Now we can use this crate to rewrite our `keyboard_interrupt_handler`:
@@ -673,13 +673,15 @@ Now we can use this crate to rewrite our `keyboard_interrupt_handler`:
extern "x86-interrupt" fn keyboard_interrupt_handler(
_stack_frame: &mut InterruptStackFrame)
{
use x86_64::instructions::port::Port;
use pc_keyboard::{Keyboard, ScancodeSet1, DecodedKey, layouts};
use pc_keyboard::{layouts, DecodedKey, HandleControl, Keyboard, ScancodeSet1};
use spin::Mutex;
use x86_64::instructions::port::Port;
lazy_static! {
static ref KEYBOARD: Mutex<Keyboard<layouts::Us104Key, ScancodeSet1>> =
Mutex::new(Keyboard::new(layouts::Us104Key, ScancodeSet1));
Mutex::new(Keyboard::new(layouts::Us104Key, ScancodeSet1,
HandleControl::Ignore)
);
}
let mut keyboard = KEYBOARD.lock();
@@ -702,15 +704,19 @@ extern "x86-interrupt" fn keyboard_interrupt_handler(
}
```
We use the `lazy_static` macro to create a static [`Keyboard`] object protected by a Mutex. On each interrupt, we lock the Mutex, read the scancode from the keyboard controller and pass it to the [`add_byte`] method, which translates the scancode into an `Option<KeyEvent>`. The [`KeyEvent`] contains which key caused the event and whether it was a press or release event.
We use the `lazy_static` macro to create a static [`Keyboard`] object protected by a Mutex. We initialize the `Keyboard` with an US keyboard layout and the scancode set 1. The [`HandleControl`] parameter allows to map `ctrl+[a-z]` to the Unicode characters `U+0001` through `U+001A`. We don't want to do that, so we use the `Ignore` option to handle the `ctrl` like normal keys.
[`Keyboard`]: https://docs.rs/pc-keyboard/0.3.1/pc_keyboard/struct.Keyboard.html
[`add_byte`]: https://docs.rs/pc-keyboard/0.3.1/pc_keyboard/struct.Keyboard.html#method.add_byte
[`KeyEvent`]: https://docs.rs/pc-keyboard/0.3.1/pc_keyboard/struct.KeyEvent.html
[`HandleControl`]: https://docs.rs/pc-keyboard/0.5.0/pc_keyboard/enum.HandleControl.html
On each interrupt, we lock the Mutex, read the scancode from the keyboard controller and pass it to the [`add_byte`] method, which translates the scancode into an `Option<KeyEvent>`. The [`KeyEvent`] contains which key caused the event and whether it was a press or release event.
[`Keyboard`]: https://docs.rs/pc-keyboard/0.5.0/pc_keyboard/struct.Keyboard.html
[`add_byte`]: https://docs.rs/pc-keyboard/0.5.0/pc_keyboard/struct.Keyboard.html#method.add_byte
[`KeyEvent`]: https://docs.rs/pc-keyboard/0.5.0/pc_keyboard/struct.KeyEvent.html
To interpret this key event, we pass it to the [`process_keyevent`] method, which translates the key event to a character if possible. For example, translates a press event of the `A` key to either a lowercase `a` character or an uppercase `A` character, depending on whether the shift key was pressed.
[`process_keyevent`]: https://docs.rs/pc-keyboard/0.3.1/pc_keyboard/struct.Keyboard.html#method.process_keyevent
[`process_keyevent`]: https://docs.rs/pc-keyboard/0.5.0/pc_keyboard/struct.Keyboard.html#method.process_keyevent
With this modified interrupt handler we can now write text: