Button debouncing

[trappitsch]

I have been playing around with the teensy4 in Rust and really enjoy the bsp, thanks @mciantyre!

Hooking up a button and using it to drive a counter via a hardware interrupt, I can't find any good way of debouncing the button easily. Is this something that is currently implemented and I just haven't found it yet / am I missing something here?
I have played with using a gpt for this and have thought about using the srtc for it too. A non-blocking debouncing routine for RTIC is not too complicated, however, it is kind of clunky... Here's my current playground approach.

In brief, the following lines describe the button and the debounce with a bunch of shared resources:

    #[task(binds = GPIO4_COMBINED_0_15, shared = [counter, gpt], local = [button, debounce_cycles])]
    fn button_pressed(mut cx: button_pressed::Context) {

        // some complicated debounce routine...
        let mut debounce_active = false;
        cx.shared.gpt.lock(|gpt| {
            let current_time = gpt.count();
            // setup debounce time for the first time
            if *cx.local.debounce_cycles == 0 {
                // first press
                *cx.local.debounce_cycles = current_time + 100_000;
            } else if current_time > *cx.local.debounce_cycles {
                // second press debounced
                *cx.local.debounce_cycles = 0;
            } else {
                // not debounced yet
                debounce_active = true;
            }
        });
        cx.local.button.clear_triggered();

        if !debounce_active {
            cx.shared.counter.lock(|cnt| {
                *cnt += 1;
            });
            blink_led::spawn().ok();
        }
    }

The full code mentioned above also has some logging over USB in it to make testing a bit easier.

Anyway, if anybody has a better/different/cooler approach, I'd be very happy :) Thanks so much!