embedded-c-sdk-bind-hal 0.13.0

use crate::ll_api::ll_cmd::*;
use embedded_hal::delay::DelayNs;
use fugit::{Duration, TimerDurationU32};
use portable_atomic::{AtomicU32, Ordering};

pub const TICK_FREQ_HZ: u32 = crate::tick_freq_hz::TICK_FREQ_HZ;

#[cfg(not(feature = "tick-size-64bit"))]
pub type TickType = u32;
#[cfg(feature = "tick-size-64bit")]
pub type TickType = u64;

static SYS_TICK_0: AtomicU32 = AtomicU32::new(0);
#[cfg(feature = "tick-size-64bit")]
static SYS_TICK_1: AtomicU32 = AtomicU32::new(0);

pub trait HalTickHandler {
    unsafe fn on_sys_tick_interrupt();
}

impl HalTickHandler for Tick {
    /// This function is called by a hardware interrupt to update the system's tick count.
    /// Depending on the build features, it supports either 32-bit or 64-bit tick counters.
    ///
    #[inline]
    unsafe fn on_sys_tick_interrupt() {
        // Increment the low-order 32-bit tick counter atomically.
        #[cfg(any(feature = "tick-size-64bit", feature = "embassy"))]
        let sys_tick = SYS_TICK_0.fetch_add(1, Ordering::Relaxed);

        // Increment the low-order 32-bit tick counter using a method compatible with non-64bit environments.
        #[cfg(not(any(feature = "tick-size-64bit", feature = "embassy")))]
        SYS_TICK_0.add(1, Ordering::Relaxed);

        // Handle 64-bit tick overflow and update the high-order 32-bit tick counter.
        #[cfg(feature = "tick-size-64bit")]
        let sys_tick = if sys_tick == u32::MAX {
            let tick_1 = SYS_TICK_1.fetch_add(1, Ordering::Release);
            ((tick_1 as u64) << 32) | (sys_tick as u64)
        } else {
            let tick_1 = SYS_TICK_1.load(Ordering::Relaxed);
            ((tick_1 as u64) << 32) | (sys_tick as u64)
        };

        // If the 'embassy' feature is enabled, check for any alarms that need to be triggered.
        #[cfg(feature = "embassy")]
        tick_time_driver::check_alarm(sys_tick);
    }
}

/// Callback function for C FFI to increment the system tick counter.
/// This function is called from C code to trigger a system tick increment,
/// which updates the internal tick counter used for timing operations.
#[unsafe(no_mangle)]
unsafe extern "C" fn sys_tick_inc() {
    unsafe { Tick::on_sys_tick_interrupt() };
}

/// Represents a point in time as measured by the system tick counter.
///
/// This struct is used to keep track of time in terms of ticks, which can be compared or used to measure elapsed time.
#[derive(Copy, Clone, Debug, Eq, PartialEq, Ord, PartialOrd, Default)]
pub struct Tick(TickType);

impl Tick {
    /// Returns the current system tick value.
    ///
    /// # Examples
    /// ```
    /// let current_tick = Tick::now();
    /// ```
    pub fn now() -> Self {
        // For 64-bit ticks, ensure we get a consistent snapshot of both high and low parts.
        #[cfg(feature = "tick-size-64bit")]
        loop {
            let t0 = SYS_TICK_1.load(Ordering::SeqCst);
            let t = SYS_TICK_0.load(Ordering::SeqCst);
            let t1 = SYS_TICK_1.load(Ordering::SeqCst);
            if t0 == t1 {
                break Tick(((t0 as u64) << 32) | (t as u64));
            }
        }
        // For 32-bit ticks, simply load the tick counter.
        #[cfg(not(feature = "tick-size-64bit"))]
        Tick(SYS_TICK_0.load(Ordering::Relaxed))
    }

    /// Computes the number of ticks elapsed since the creation of this `Tick` instance.
    ///
    /// # Examples
    /// ```
    /// let start_tick = Tick::now();
    /// let elapsed_ticks = start_tick.elapsed();
    /// ```
    pub fn elapsed(self) -> TickType {
        if let Some(tick) = Self::now().0.checked_sub(self.0) {
            tick
        } else {
            TickType::MAX
        }
    }

    /// Creates a new `Tick` instance with the given value.
    ///
    /// # Arguments
    /// * `value` - The value to initialize the `Tick` with.
    ///
    /// # Returns
    /// * A new `Tick` instance.
    #[inline]
    pub const fn with_value(value: TickType) -> Self {
        Tick(value)
    }

    /// Retrieves the current tick value.
    ///
    /// # Returns
    /// * The current tick value.
    #[inline]
    pub fn tick() -> TickType {
        Self::now().0
    }

    /// Calculates the elapsed time since the creation of the `Tick` instance.
    ///
    /// # Returns
    /// * A `Duration` representing the elapsed time in ticks.
    pub fn elapsed_time(self) -> Duration<TickType, 1, TICK_FREQ_HZ> {
        let tick = if let Some(res) = Self::now().0.checked_sub(self.0) {
            res
        } else {
            TickType::MAX
        };

        Duration::<TickType, 1, TICK_FREQ_HZ>::from_ticks(tick)
    }

    /// Checks if the specified duration has elapsed since the last check.
    ///
    /// # Arguments
    /// * `duration` - The duration to check for in ticks.
    ///
    /// # Returns
    /// * `true` if the specified duration has elapsed, `false` otherwise.
    pub fn every(&mut self, duration: TickType) -> bool {
        let timeout = if let Some(elapsed) = Self::now().0.checked_sub(self.0) {
            if elapsed >= duration { true } else { false }
        } else {
            true
        };

        if timeout {
            self.0 = Self::now().0;
        }
        return timeout;
    }

    /// Resets the tick counter to the current system tick value.
    pub fn reset(&mut self) {
        self.0 = Self::now().0;
    }
}

impl core::ops::Add for Tick {
    type Output = Self;

    fn add(self, rhs: Self) -> Self::Output {
        Tick(self.0 + rhs.0)
    }
}

impl core::ops::Sub for Tick {
    type Output = Self;

    fn sub(self, rhs: Self) -> Self::Output {
        Tick(self.0 - rhs.0)
    }
}

/// A delay utility that allows for precise timing delays based on a specified tick frequency.
///
/// This struct provides methods to create a delay object and then use it to delay for a specific amount of time.
/// The delay is implemented using the system's tick counter and can be configured for different frequencies.
///
/// # Examples
/// ```
/// let mut delay = Delay::new(); // Create a delay object for a 1000 Hz tick frequency.
/// delay.delay_ms(500); // Delay for 500 milliseconds.
/// ```
#[derive(Debug, Clone, Copy)]
pub struct Delay;

impl Delay {
    /// Creates a new `Delay` instance for the specified tick frequency.
    ///
    /// # Examples
    /// ```
    /// let mut delay = Delay::new(); // Create a delay object for a 1000 Hz tick frequency.
    /// ```
    pub const fn new() -> Self {
        Delay
    }
}

/// Trait implementation for delaying in nanoseconds.
impl DelayNs for Delay {
    /// Delays for a specified number of nanoseconds.
    ///
    /// # Examples
    /// ```
    /// let mut delay = Delay::new();
    /// delay.delay_ns(1_000_000); // Delay for 1 millisecond (1,000,000 nanoseconds).
    /// ```
    #[inline]
    fn delay_ns(&mut self, ns: u32) {
        ll_invoke_inner!(INVOKE_ID_DELAY_NANO, ns);
    }

    /// Delays for a specified number of milliseconds.
    ///
    /// # Examples
    /// ```
    /// let mut delay = Delay::new();
    /// delay.delay_ms(500); // Delay for 500 milliseconds.
    /// ```
    #[cfg(feature = "tick-based-msdelay")]
    #[inline]
    fn delay_ms(&mut self, ms: u32) {
        let ms_tick = TimerDurationU32::<TICK_FREQ_HZ>::millis(ms).ticks();
        let start = Tick::now();
        loop {
            unsafe {
                core::arch::asm!("wfi");
            }
            if (start.elapsed() as u32) >= ms_tick {
                break;
            }
        }
    }
}

#[cfg(feature = "embassy")]
mod tick_time_driver {
    use core::cell::{Cell, RefCell};
    use embassy_sync::blocking_mutex::Mutex;
    use embassy_sync::blocking_mutex::raw::CriticalSectionRawMutex;
    use embassy_time_driver::Driver;
    use embassy_time_queue_utils::Queue;

    struct AlarmState {
        timestamp: Cell<super::TickType>,
    }
    unsafe impl Send for AlarmState {}

    struct TimerDriver {
        alarms: Mutex<CriticalSectionRawMutex, AlarmState>,
        queue: Mutex<CriticalSectionRawMutex, RefCell<Queue>>,
    }

    embassy_time_driver::time_driver_impl!(static DRIVER: TimerDriver = TimerDriver{
        alarms:  Mutex::const_new(CriticalSectionRawMutex::new(), AlarmState {
            timestamp: Cell::new(0),
        }),
        queue: Mutex::new(RefCell::new(Queue::new()))
    });

    #[inline(always)]
    pub fn check_alarm(curr_tick: super::TickType) {
        DRIVER.check_alarm(curr_tick);
    }

    impl TimerDriver {
        /// Internal function to check and trigger alarms.
        ///
        /// This function enters a critical section to safely access shared resources and checks if there is an alarm
        /// set to go off at the current tick. If an alarm is due, it resets the alarm timestamp and invokes the callback.
        fn check_alarm(&self, curr_tick: super::TickType) {
            critical_section::with(|cs| {
                let alarm = &self.alarms.borrow(cs);
                let mut timestamp = alarm.timestamp.get();
                while timestamp <= curr_tick {
                    let mut queue = self.queue.borrow(cs).borrow_mut();
                    timestamp = queue.next_expiration(curr_tick as u64) as super::TickType; //get next timestamp
                    alarm.timestamp.set(timestamp); //set next alarm
                }
            });
        }
    }

    impl Driver for TimerDriver {
        fn now(&self) -> u64 {
            super::Tick::now().0 as u64
        }

        fn schedule_wake(&self, at: u64, waker: &core::task::Waker) {
            critical_section::with(|cs| {
                let mut queue = self.queue.borrow(cs).borrow_mut();

                if queue.schedule_wake(at, waker) {
                    let alarm = &self.alarms.borrow(cs);
                    let now = self.now();
                    loop {
                        let timestamp = queue.next_expiration(now) as super::TickType; //get next timestamp
                        alarm.timestamp.set(timestamp); //set next alarm
                        if timestamp > now as super::TickType {
                            break;
                        }
                    }
                }
            })
        }
    }
}