embassy/time: make optional via Cargo feature

embassy-nrf/Cargo.toml

@@ -21,7 +21,7 @@ nrf52840 = ["nrf52840-pac"]
 
 
 [dependencies]
-embassy = { version = "0.1.0", path = "../embassy" }
+embassy = { version = "0.1.0", path = "../embassy", features = ["time-tick-32768hz"] }
 embassy-macros = { version = "0.1.0", path = "../embassy-macros", features = ["nrf"]}
 embassy-extras = {version = "0.1.0", path = "../embassy-extras" }
 

embassy-rp/Cargo.toml

@@ -12,7 +12,7 @@ defmt-warn = [ ]
 defmt-error = [ ]
 
 [dependencies]
-embassy = { version = "0.1.0", path = "../embassy" }
+embassy = { version = "0.1.0", path = "../embassy", features = [ "time-tick-1mhz" ] }
 embassy-extras = {version = "0.1.0", path = "../embassy-extras" }
 embassy-macros = { version = "0.1.0", path = "../embassy-macros", features = ["rp"]}
 

embassy-std/Cargo.toml

@@ -5,6 +5,6 @@ authors = ["Dario Nieuwenhuis <dirbaio@dirbaio.net>"]
 edition = "2018"
 
 [dependencies]
-embassy     = { version = "0.1.0", path = "../embassy", features = ["std"] }
+embassy = { version = "0.1.0", path = "../embassy", features = ["std", "time-tick-32768hz"] }
 embassy-macros = { version = "0.1.0", path = "../embassy-macros", features = ["std"]}
 lazy_static = "1.4.0"

embassy-stm32/Cargo.toml

@@ -6,7 +6,7 @@ edition = "2018"
 resolver = "2"
 
 [dependencies]
-embassy = { version = "0.1.0", path = "../embassy" }
+embassy = { version = "0.1.0", path = "../embassy", features = ["time-tick-32768hz"] }
 embassy-macros = { version = "0.1.0", path = "../embassy-macros", features = ["stm32"] }
 embassy-extras = {version = "0.1.0", path = "../embassy-extras" }
 embassy-traits = {version = "0.1.0", path = "../embassy-traits" }

embassy/Cargo.toml

@@ -5,11 +5,13 @@ authors = ["Dario Nieuwenhuis <dirbaio@dirbaio.net>"]
 edition = "2018"
 
 [features]
-default = ["tick-32768hz"]
+default = []
 std = ["futures/std", "embassy-traits/std"]
-tick-32768hz = []
-tick-1000hz = []
-tick-1mhz = []
+
+time = []
+time-tick-32768hz = ["time"]
+time-tick-1000hz = ["time"]
+time-tick-1mhz = ["time"]
 
 defmt-trace = []
 defmt-debug = []

embassy/src/executor/mod.rs

@@ -4,12 +4,12 @@ use core::{mem, ptr};
 
 pub mod raw;
 mod run_queue;
+#[cfg(feature = "time")]
 mod timer_queue;
 mod util;
 mod waker;
 
 use crate::interrupt::{Interrupt, InterruptExt};
-use crate::time::Alarm;
 
 #[must_use = "Calling a task function does nothing on its own. You must pass the returned SpawnToken to Executor::spawn()"]
 pub struct SpawnToken<F> {
@@ -116,7 +116,8 @@ impl Executor {
         }
     }
 
-    pub fn set_alarm(&mut self, alarm: &'static dyn Alarm) {
+    #[cfg(feature = "time")]
+    pub fn set_alarm(&mut self, alarm: &'static dyn crate::time::Alarm) {
         self.inner.set_alarm(alarm);
     }
 
@@ -160,7 +161,8 @@ impl<I: Interrupt> InterruptExecutor<I> {
         }
     }
 
-    pub fn set_alarm(&mut self, alarm: &'static dyn Alarm) {
+    #[cfg(feature = "time")]
+    pub fn set_alarm(&mut self, alarm: &'static dyn crate::time::Alarm) {
         self.inner.set_alarm(alarm);
     }
 

embassy/src/executor/raw.rs

@@ -1,18 +1,20 @@
 use atomic_polyfill::{AtomicU32, Ordering};
 use core::cell::Cell;
-use core::cmp::min;
 use core::future::Future;
 use core::marker::PhantomData;
 use core::pin::Pin;
 use core::ptr::NonNull;
-use core::task::{Context, Poll, Waker};
+use core::task::{Context, Poll};
 use core::{mem, ptr};
 
 use super::run_queue::{RunQueue, RunQueueItem};
-use super::timer_queue::{TimerQueue, TimerQueueItem};
 use super::util::UninitCell;
 use super::waker;
 use super::SpawnToken;
+
+#[cfg(feature = "time")]
+use super::timer_queue::{TimerQueue, TimerQueueItem};
+#[cfg(feature = "time")]
 use crate::time::{Alarm, Instant};
 
 /// Task is spawned (has a future)
@@ -20,26 +22,33 @@ pub(crate) const STATE_SPAWNED: u32 = 1 << 0;
 /// Task is in the executor run queue
 pub(crate) const STATE_RUN_QUEUED: u32 = 1 << 1;
 /// Task is in the executor timer queue
+#[cfg(feature = "time")]
 pub(crate) const STATE_TIMER_QUEUED: u32 = 1 << 2;
 
 pub struct TaskHeader {
     pub(crate) state: AtomicU32,
     pub(crate) run_queue_item: RunQueueItem,
-    pub(crate) expires_at: Cell<Instant>,
-    pub(crate) timer_queue_item: TimerQueueItem,
     pub(crate) executor: Cell<*const Executor>, // Valid if state != 0
     pub(crate) poll_fn: UninitCell<unsafe fn(NonNull<TaskHeader>)>, // Valid if STATE_SPAWNED
+
+    #[cfg(feature = "time")]
+    pub(crate) expires_at: Cell<Instant>,
+    #[cfg(feature = "time")]
+    pub(crate) timer_queue_item: TimerQueueItem,
 }
 
 impl TaskHeader {
     pub(crate) const fn new() -> Self {
         Self {
             state: AtomicU32::new(0),
-            expires_at: Cell::new(Instant::from_ticks(0)),
             run_queue_item: RunQueueItem::new(),
-            timer_queue_item: TimerQueueItem::new(),
             executor: Cell::new(ptr::null()),
             poll_fn: UninitCell::uninit(),
+
+            #[cfg(feature = "time")]
+            expires_at: Cell::new(Instant::from_ticks(0)),
+            #[cfg(feature = "time")]
+            timer_queue_item: TimerQueueItem::new(),
         }
     }
 
@@ -154,9 +163,12 @@ unsafe impl<F: Future + 'static> Sync for Task<F> {}
 
 pub struct Executor {
     run_queue: RunQueue,
-    timer_queue: TimerQueue,
     signal_fn: fn(*mut ()),
     signal_ctx: *mut (),
+
+    #[cfg(feature = "time")]
+    timer_queue: TimerQueue,
+    #[cfg(feature = "time")]
     alarm: Option<&'static dyn Alarm>,
 }
 
@@ -164,13 +176,17 @@ impl Executor {
     pub const fn new(signal_fn: fn(*mut ()), signal_ctx: *mut ()) -> Self {
         Self {
             run_queue: RunQueue::new(),
-            timer_queue: TimerQueue::new(),
             signal_fn,
             signal_ctx,
+
+            #[cfg(feature = "time")]
+            timer_queue: TimerQueue::new(),
+            #[cfg(feature = "time")]
             alarm: None,
         }
     }
 
+    #[cfg(feature = "time")]
     pub fn set_alarm(&mut self, alarm: &'static dyn Alarm) {
         self.alarm = Some(alarm);
     }
@@ -192,6 +208,7 @@ impl Executor {
     }
 
     pub unsafe fn run_queued(&'static self) {
+        #[cfg(feature = "time")]
         if self.alarm.is_some() {
             self.timer_queue.dequeue_expired(Instant::now(), |p| {
                 p.as_ref().enqueue();
@@ -200,6 +217,8 @@ impl Executor {
 
         self.run_queue.dequeue_all(|p| {
             let task = p.as_ref();
+
+            #[cfg(feature = "time")]
             task.expires_at.set(Instant::MAX);
 
             let state = task.state.fetch_and(!STATE_RUN_QUEUED, Ordering::AcqRel);
@@ -216,11 +235,13 @@ impl Executor {
             task.poll_fn.read()(p as _);
 
             // Enqueue or update into timer_queue
+            #[cfg(feature = "time")]
             self.timer_queue.update(p);
         });
 
         // If this is in the past, set_alarm will immediately trigger the alarm,
         // which will make the wfe immediately return so we do another loop iteration.
+        #[cfg(feature = "time")]
         if let Some(alarm) = self.alarm {
             let next_expiration = self.timer_queue.next_expiration();
             alarm.set_callback(self.signal_fn, self.signal_ctx);
@@ -242,9 +263,10 @@ pub unsafe fn wake_task(task: NonNull<TaskHeader>) {
     task.as_ref().enqueue();
 }
 
-pub(crate) unsafe fn register_timer(at: Instant, waker: &Waker) {
+#[cfg(feature = "time")]
+pub(crate) unsafe fn register_timer(at: Instant, waker: &core::task::Waker) {
     let task = waker::task_from_waker(waker);
     let task = task.as_ref();
     let expires_at = task.expires_at.get();
-    task.expires_at.set(min(expires_at, at));
+    task.expires_at.set(expires_at.min(at));
 }

embassy/src/lib.rs

@@ -14,6 +14,7 @@ pub(crate) mod fmt;
 pub mod executor;
 pub mod interrupt;
 pub mod io;
+#[cfg(feature = "time")]
 pub mod time;
 pub mod util;
 

embassy/src/time/mod.rs

@@ -13,21 +13,13 @@ pub use instant::Instant;
 pub use timer::{with_timeout, Ticker, TimeoutError, Timer};
 pub use traits::*;
 
-#[cfg(any(
-    all(feature = "tick-32768hz", feature = "tick-1000hz"),
-    all(feature = "tick-32768hz", feature = "tick-1mhz"),
-))]
-compile_error!(
-    "Disable default-features to be able to use a tick rate other than the default (32768 Hz)"
-);
-
-#[cfg(feature = "tick-1000hz")]
+#[cfg(feature = "time-tick-1000hz")]
 pub const TICKS_PER_SECOND: u64 = 1_000;
 
-#[cfg(feature = "tick-32768hz")]
+#[cfg(feature = "time-tick-32768hz")]
 pub const TICKS_PER_SECOND: u64 = 32_768;
 
-#[cfg(feature = "tick-1mhz")]
+#[cfg(feature = "time-tick-1mhz")]
 pub const TICKS_PER_SECOND: u64 = 1_000_000;
 
 static mut CLOCK: Option<&'static dyn Clock> = None;