rt 0.19.1

A real-time operating system capable of full preemption
Documentation 
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use core::{cell::UnsafeCell, mem::zeroed};

use crate::{
    bindings::{
        rt_timer, rt_timer_change_period, rt_timer_command, rt_timer_daemon, rt_timer_fn,
        rt_timer_start, rt_timer_stop, rt_timer_timedchange_period, rt_timer_timedstart,
        rt_timer_timedstop, rt_timer_trychange_period, rt_timer_trystart, rt_timer_trystop,
    },
    list::list_init,
    ptr_macros::{ptr_to_field, ptr_to_field_mut},
    sync::Queue,
    tick::Utick,
};

#[repr(transparent)]
pub struct Timer {
    timer: UnsafeCell<rt_timer>,
}

unsafe impl Send for Timer {}
unsafe impl Sync for Timer {}

#[repr(transparent)]
pub struct TimerCommand(rt_timer_command);

unsafe impl Send for TimerCommand {}
unsafe impl Sync for TimerCommand {}

impl Timer {
    /// Initialize a new `Timer` with the given queue, function, and periodicity.
    ///
    /// # Safety
    ///
    /// This must be called with a pointer to a `static` `Timer` and be used to initialize that
    /// same `Timer`. Users should use the `rt::timer_periodic!` or `rt::timer_one_shot!` macros to
    /// create a `Timer` rather than call `Timer::init` directly.
    #[must_use]
    pub const unsafe fn init(
        this: *const Self,
        queue: &'static Queue<TimerCommand>,
        f: extern "C" fn(),
        periodic: bool,
        period: Utick,
    ) -> Timer {
        let timer = UnsafeCell::raw_get(ptr_to_field!(this, timer));
        Timer {
            timer: UnsafeCell::new(rt_timer {
                list: list_init(ptr_to_field_mut!(timer, list)),
                tick: 0,
                period,
                fn_: unsafe {
                    let mut x: rt_timer_fn = zeroed();
                    x.no_arg = Some(f);
                    x
                },
                arg: 0,
                queue: queue.queue.get(),
                has_arg: false,
                periodic,
            }),
        }
    }

    pub fn start(&self) {
        unsafe { rt_timer_start(self.timer.get()) }
    }

    pub fn try_start(&self) -> bool {
        unsafe { rt_timer_trystart(self.timer.get()) }
    }

    pub fn timed_start(&self, block_ticks: Utick) -> bool {
        unsafe { rt_timer_timedstart(self.timer.get(), block_ticks) }
    }

    pub fn stop(&self) {
        unsafe { rt_timer_stop(self.timer.get()) }
    }

    pub fn try_stop(&self) -> bool {
        unsafe { rt_timer_trystop(self.timer.get()) }
    }

    pub fn timed_stop(&self, block_ticks: Utick) -> bool {
        unsafe { rt_timer_timedstop(self.timer.get(), block_ticks) }
    }

    pub fn change_period(&self, period: Utick) {
        unsafe { rt_timer_change_period(self.timer.get(), period) }
    }

    pub fn try_change_period(&self, period: Utick) -> bool {
        unsafe { rt_timer_trychange_period(self.timer.get(), period) }
    }

    pub fn timed_change_period(&self, period: Utick, block_ticks: Utick) -> bool {
        unsafe { rt_timer_timedchange_period(self.timer.get(), period, block_ticks) }
    }
}

pub fn timer_daemon(queue: &'static Queue<TimerCommand>) {
    let queue_addr = queue.queue.get().addr();
    unsafe { rt_timer_daemon(queue_addr) }
}

#[macro_export]
macro_rules! timer_queue {
    ($name: ident, $depth: expr) => {
        $crate::queue!($name, $crate::timer::TimerCommand, $depth);
    };
}

#[macro_export]
macro_rules! timer_task {
    ($queue: expr, $stack_size: expr, $priority: expr$(, $mpu_regions: expr)*) => {
        const _: () = {
            use $crate::timer::timer_daemon;
            $crate::task!(timer_daemon($queue), $stack_size, $priority $(, $mpu_regions)*);
        };
    };
}

#[macro_export]
macro_rules! timer_common {
    ($name: ident, $queue: expr, $fn: ident, $periodic: expr, $period: expr) => {
        $crate::timer_common!($name, $queue, $fn(), $periodic, $period);
    };

    ($name: ident, $queue: expr, $expr: expr, $periodic: expr, $period: expr) => {
        static $name: $crate::timer::Timer = {
            let ptr = &raw const $name;
            let queue = $queue;
            extern "C" fn timer_fn() {
                $expr;
            }
            let periodic = $periodic;
            let period = $period;
            unsafe { $crate::timer::Timer::init(ptr, queue, timer_fn, periodic, period) }
        };
    };
}

#[macro_export]
macro_rules! timer_periodic {
    ($name: ident, $queue: expr, $fn: ident, $period: expr) => {
        $crate::timer_common!($name, $queue, $fn, true, $period);
    };
    ($name: ident, $queue: expr, $expr: expr, $period: expr) => {
        $crate::timer_common!($name, $queue, $expr, true, $period);
    };
}

#[macro_export]
macro_rules! timer_one_shot {
    ($name: ident, $queue: expr, $fn: ident, $period: expr) => {
        $crate::timer_common!($name, $queue, $fn, false, $period);
    };
    ($name: ident, $queue: expr, $expr: expr, $period: expr) => {
        $crate::timer_common!($name, $queue, $expr, false, $period);
    };
}

#[macro_export]
macro_rules! timer_autostart {
    ($name: ident) => {
        const _: () = {
            extern "C" fn timer_autostart() {
                assert!($name.try_start(), "can't autostart timer");
            }
            $crate::ctor!(TIMER_AUTOSTART, timer_autostart);
        };
    };
}