Simplify Systick Monotonic by integrating the TQ

rtic-monotonics/src/systick_monotonic.rs

@@ -3,7 +3,7 @@
 use super::Monotonic;
 pub use super::{TimeoutError, TimerQueue};
 use atomic_polyfill::{AtomicU32, Ordering};
-use core::ops::Deref;
+use core::future::Future;
 use cortex_m::peripheral::SYST;
 use embedded_hal_async::delay::DelayUs;
 pub use fugit::ExtU32;
@@ -30,8 +30,7 @@ impl Systick {
     /// `sysclk` and `TIMER_HZ`.
     ///
     /// Note: Give the return value to `TimerQueue::initialize()` to initialize the timer queue.
-    #[must_use]
-    pub fn start(mut systick: cortex_m::peripheral::SYST, sysclk: u32) -> Self {
+    pub fn start(mut systick: cortex_m::peripheral::SYST, sysclk: u32) {
         // + TIMER_HZ / 2 provides round to nearest instead of round to 0.
         // - 1 as the counter range is inclusive [0, reload]
         let reload = (sysclk + TIMER_HZ / 2) / TIMER_HZ - 1;
@@ -45,7 +44,7 @@ impl Systick {
         systick.enable_interrupt();
         systick.enable_counter();
 
-        Systick {}
+        SYSTICK_TIMER_QUEUE.initialize(Systick {});
     }
 
     fn systick() -> SYST {
@@ -54,6 +53,44 @@ impl Systick {
 }
 
 static SYSTICK_CNT: AtomicU32 = AtomicU32::new(0);
+static SYSTICK_TIMER_QUEUE: TimerQueue<Systick> = TimerQueue::new();
+
+// Forward timerqueue interface
+impl Systick {
+    /// Used to access the underlying timer queue
+    #[doc(hidden)]
+    pub fn __tq() -> &'static TimerQueue<Systick> {
+        &SYSTICK_TIMER_QUEUE
+    }
+
+    /// Timeout at a specific time.
+    pub async fn timeout_at<F: Future>(
+        instant: <Self as Monotonic>::Instant,
+        future: F,
+    ) -> Result<F::Output, TimeoutError> {
+        SYSTICK_TIMER_QUEUE.timeout_at(instant, future).await
+    }
+
+    /// Timeout after a specific duration.
+    #[inline]
+    pub async fn timeout_after<F: Future>(
+        duration: <Self as Monotonic>::Duration,
+        future: F,
+    ) -> Result<F::Output, TimeoutError> {
+        SYSTICK_TIMER_QUEUE.timeout_after(duration, future).await
+    }
+
+    /// Delay for some duration of time.
+    #[inline]
+    pub async fn delay(duration: <Self as Monotonic>::Duration) {
+        SYSTICK_TIMER_QUEUE.delay(duration).await;
+    }
+
+    /// Delay to some specific time instant.
+    pub async fn delay_until(instant: <Self as Monotonic>::Instant) {
+        SYSTICK_TIMER_QUEUE.delay_until(instant).await;
+    }
+}
 
 impl Monotonic for Systick {
     type Instant = fugit::TimerInstantU32<TIMER_HZ>;
@@ -92,49 +129,28 @@ impl Monotonic for Systick {
     fn disable_timer() {}
 }
 
-/// Timer queue wrapper to implement traits on
-pub struct SystickTimerQueue(TimerQueue<Systick>);
-
-impl SystickTimerQueue {
-    /// Create a new timer queue.
-    pub const fn new() -> Self {
-        Self(TimerQueue::new())
-    }
-}
-
-impl Deref for SystickTimerQueue {
-    type Target = TimerQueue<Systick>;
-
-    #[inline(always)]
-    fn deref(&self) -> &Self::Target {
-        &self.0
-    }
-}
-
-impl DelayUs for SystickTimerQueue {
+impl DelayUs for Systick {
     type Error = core::convert::Infallible;
 
     async fn delay_us(&mut self, us: u32) -> Result<(), Self::Error> {
-        self.delay(us.micros()).await;
+        SYSTICK_TIMER_QUEUE.delay(us.micros()).await;
         Ok(())
     }
 
     async fn delay_ms(&mut self, ms: u32) -> Result<(), Self::Error> {
-        self.delay(ms.millis()).await;
+        SYSTICK_TIMER_QUEUE.delay(ms.millis()).await;
         Ok(())
     }
 }
 
-/// Register the Systick interrupt and crate a timer queue with a specific name and speed.
+/// Register the Systick interrupt for the monotonic.
 #[macro_export]
-macro_rules! make_systick_timer_queue {
-    ($timer_queue_name:ident) => {
-        static $timer_queue_name: SystickTimerQueue = SystickTimerQueue::new();
-
+macro_rules! make_systick_handler {
+    () => {
         #[no_mangle]
         #[allow(non_snake_case)]
         unsafe extern "C" fn SysTick() {
-            $timer_queue_name.on_monotonic_interrupt();
+            Systick::__tq().on_monotonic_interrupt();
         }
     };
 }

rtic/examples/async-delay.rs

@@ -11,7 +11,7 @@ mod app {
     use cortex_m_semihosting::{debug, hprintln};
     use rtic_monotonics::systick_monotonic::*;
 
-    rtic_monotonics::make_systick_timer_queue!(TIMER);
+    rtic_monotonics::make_systick_handler!();
 
     #[shared]
     struct Shared {}
@@ -23,8 +23,7 @@ mod app {
     fn init(cx: init::Context) -> (Shared, Local) {
         hprintln!("init");
 
-        let systick = Systick::start(cx.core.SYST, 12_000_000);
-        TIMER.initialize(systick);
+        Systick::start(cx.core.SYST, 12_000_000);
 
         foo::spawn().ok();
         bar::spawn().ok();
@@ -45,21 +44,21 @@ mod app {
     #[task]
     async fn foo(_cx: foo::Context) {
         hprintln!("hello from foo");
-        TIMER.delay(100.millis()).await;
+        Systick::delay(100.millis()).await;
         hprintln!("bye from foo");
     }
 
     #[task]
     async fn bar(_cx: bar::Context) {
         hprintln!("hello from bar");
-        TIMER.delay(200.millis()).await;
+        Systick::delay(200.millis()).await;
         hprintln!("bye from bar");
     }
 
     #[task]
     async fn baz(_cx: baz::Context) {
         hprintln!("hello from baz");
-        TIMER.delay(300.millis()).await;
+        Systick::delay(300.millis()).await;
         hprintln!("bye from baz");
 
         debug::exit(debug::EXIT_SUCCESS);

rtic/examples/async-timeout.rs

@@ -12,8 +12,9 @@ use rtic_monotonics::systick_monotonic::*;
 mod app {
     use super::*;
     use futures::{future::FutureExt, select_biased};
+    use rtic_monotonics::Monotonic;
 
-    rtic_monotonics::make_systick_timer_queue!(TIMER);
+    rtic_monotonics::make_systick_handler!();
 
     #[shared]
     struct Shared {}
@@ -25,8 +26,7 @@ mod app {
     fn init(cx: init::Context) -> (Shared, Local) {
         hprintln!("init");
 
-        let systick = Systick::start(cx.core.SYST, 12_000_000);
-        TIMER.initialize(systick);
+        Systick::start(cx.core.SYST, 12_000_000);
 
         foo::spawn().ok();
 
@@ -37,37 +37,37 @@ mod app {
     async fn foo(_cx: foo::Context) {
         // Call hal with short relative timeout using `select_biased`
         select_biased! {
-            v = hal_get(&TIMER, 1).fuse() => hprintln!("hal returned {}", v),
-            _ = TIMER.delay(200.millis()).fuse() =>  hprintln!("timeout", ), // this will finish first
+            v = hal_get(1).fuse() => hprintln!("hal returned {}", v),
+            _ = Systick::delay(200.millis()).fuse() =>  hprintln!("timeout", ), // this will finish first
         }
 
         // Call hal with long relative timeout using `select_biased`
         select_biased! {
-            v = hal_get(&TIMER, 1).fuse() => hprintln!("hal returned {}", v), // hal finish first
-            _ = TIMER.delay(1000.millis()).fuse() =>  hprintln!("timeout", ),
+            v = hal_get(1).fuse() => hprintln!("hal returned {}", v), // hal finish first
+            _ = Systick::delay(1000.millis()).fuse() =>  hprintln!("timeout", ),
         }
 
         // Call hal with long relative timeout using monotonic `timeout_after`
-        match TIMER.timeout_after(1000.millis(), hal_get(&TIMER, 1)).await {
+        match Systick::timeout_after(1000.millis(), hal_get(1)).await {
             Ok(v) => hprintln!("hal returned {}", v),
             _ => hprintln!("timeout"),
         }
 
         // get the current time instance
-        let mut instant = TIMER.now();
+        let mut instant = Systick::now();
 
         // do this 3 times
         for n in 0..3 {
             // exact point in time without drift
             instant += 1000.millis();
-            TIMER.delay_until(instant).await;
+            Systick::delay_until(instant).await;
 
             // exact point it time for timeout
             let timeout = instant + 500.millis();
-            hprintln!("now is {:?}, timeout at {:?}", TIMER.now(), timeout);
+            hprintln!("now is {:?}, timeout at {:?}", Systick::now(), timeout);
 
-            match TIMER.timeout_at(timeout, hal_get(&TIMER, n)).await {
-                Ok(v) => hprintln!("hal returned {} at time {:?}", v, TIMER.now()),
+            match Systick::timeout_at(timeout, hal_get(n)).await {
+                Ok(v) => hprintln!("hal returned {} at time {:?}", v, Systick::now()),
                 _ => hprintln!("timeout"),
             }
         }
@@ -77,11 +77,11 @@ mod app {
 }
 
 // Emulate some hal
-async fn hal_get(timer: &'static SystickTimerQueue, n: u32) -> u32 {
+async fn hal_get(n: u32) -> u32 {
     // emulate some delay time dependent on n
     let d = 350.millis() + n * 100.millis();
     hprintln!("the hal takes a duration of {:?}", d);
-    timer.delay(d).await;
+    Systick::delay(d).await;
     // emulate some return value
     5
 }