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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -1,53 +1,121 @@ | ||
| use core::sync::atomic::{AtomicU32, Ordering}; | ||
| use core::time::Duration; | ||
| use core::cell::RefCell; | ||
| use core::ops::Add; | ||
|
|
||
| use cortex_m::interrupt::{self, Mutex}; | ||
| use cortex_m::peripheral::{SYST, syst::SystClkSource}; | ||
| use cortex_m_rt::exception; | ||
|
|
||
| use crate::Gcr; | ||
| use crate::{Gcr, HalError}; | ||
|
|
||
| const SYSTICK_RELOAD_VAL: u32 = 0xffffff; | ||
|
|
||
| pub struct Timer { | ||
| systick: SYST, | ||
| #[derive(Debug, Clone, Copy, PartialEq, Eq, PartialOrd, Ord)] | ||
| pub struct Instant { | ||
| time_since_boot: Duration, | ||
| } | ||
|
|
||
| impl Timer { | ||
| pub(crate) fn new(mut systick: SYST) -> Self { | ||
| systick.set_reload(SYSTICK_RELOAD_VAL); | ||
| systick.clear_current(); | ||
| systick.enable_counter(); | ||
| systick.set_clock_source(SystClkSource::Core); | ||
| impl Instant { | ||
| pub fn now() -> Instant { | ||
| let (current_tick, wrap_count) = interrupt::free(|token| { | ||
| let mut systick_ref = SYSTICK.borrow(token).borrow_mut(); | ||
|
|
||
| Timer { | ||
| systick, | ||
| } | ||
| } | ||
| let systick = systick_ref | ||
| .as_mut() | ||
| .expect("timer not initialized"); | ||
|
|
||
| // first read current tick | ||
| let current_tick = SYST::get_current(); | ||
|
|
||
| pub fn sleep(&mut self, duration: Duration) { | ||
| // NOTE: this systick thing counts down, not up | ||
| let start_tick = SYST::get_current(); | ||
| if systick.has_wrapped() { | ||
| // a wrap has occured, use tick count of 0 and new value for wrap count | ||
| let wrap_count = WRAP_COUNT.fetch_add(1, Ordering::Relaxed) + 1; | ||
|
|
||
| (current_tick, wrap_count) | ||
| } else { | ||
| // no wrap occured, current tick count and wrap count are accurate | ||
| (current_tick, WRAP_COUNT.load(Ordering::Relaxed)) | ||
| } | ||
| }); | ||
|
|
||
| // current tick subtracted from reaload val because it counts down | ||
| let total_ticks = (wrap_count as u64 * SYSTICK_RELOAD_VAL as u64) + (SYSTICK_RELOAD_VAL - current_tick) as u64; | ||
|
|
||
| let usecs = duration.as_micros() as u64; | ||
| let sysclock_freq = Gcr::with(|gcr| gcr.get_sysclock_frequency()) as u64; | ||
|
|
||
| // total number of ticks we need to wait for | ||
| let delay_ticks = ((usecs * sysclock_freq) / 1000000) as u32; | ||
| // calculate seconds and microseconds seperately to avoid | ||
| // potential overflow when ticks are multiplied by 1_000_000 | ||
| let seconds = total_ticks / sysclock_freq; | ||
| let remaining_ticks = total_ticks % sysclock_freq; | ||
|
|
||
| let remaining_microseconds = (remaining_ticks * 1_000_000) / sysclock_freq; | ||
| let total_microseconds = (seconds * 1_000_000) + remaining_microseconds; | ||
|
|
||
| let mut wrap_count = delay_ticks / SYSTICK_RELOAD_VAL; | ||
| let tick_count = delay_ticks % SYSTICK_RELOAD_VAL; | ||
| Instant { | ||
| time_since_boot: Duration::from_micros(total_microseconds), | ||
| } | ||
| } | ||
| } | ||
|
|
||
| let end_tick = if tick_count > start_tick { | ||
| wrap_count += 1; | ||
| (SYSTICK_RELOAD_VAL - tick_count) + start_tick | ||
| } else { | ||
| start_tick - tick_count | ||
| }; | ||
| impl Add<Duration> for Instant { | ||
| type Output = Instant; | ||
|
|
||
| while wrap_count > 0 { | ||
| if self.systick.has_wrapped() { | ||
| wrap_count -= 1; | ||
| } | ||
| fn add(self, rhs: Duration) -> Instant { | ||
| Instant { | ||
| time_since_boot: self.time_since_boot + rhs, | ||
| } | ||
| } | ||
| } | ||
|
|
||
| while SYST::get_current() > end_tick && !self.systick.has_wrapped() {} | ||
| pub fn sleep(duration: Duration) { | ||
| let start = Instant::now(); | ||
| let end = start + duration; | ||
|
|
||
| while Instant::now() < end {} | ||
| } | ||
|
|
||
| /// Runs the function, returns the result or none if it took too long | ||
| pub fn timeout<T>(f: impl FnOnce() -> T, timeout_len: Duration) -> Result<T, HalError> { | ||
| let start = Instant::now(); | ||
| let result = f(); | ||
| let end = Instant::now(); | ||
|
|
||
| if start + timeout_len < end { | ||
| Err(HalError::Timeout) | ||
| } else { | ||
| Ok(result) | ||
| } | ||
| } | ||
|
|
||
| /// Initializes the timer | ||
| pub(crate) fn init(mut systick: SYST) { | ||
| interrupt::free(|token| { | ||
| systick.set_reload(SYSTICK_RELOAD_VAL); | ||
| systick.clear_current(); | ||
| systick.enable_counter(); | ||
| systick.set_clock_source(SystClkSource::Core); | ||
| systick.enable_interrupt(); | ||
|
|
||
| let mut systick_ref = SYSTICK.borrow(token).borrow_mut(); | ||
| *systick_ref = Some(systick); | ||
| }) | ||
| } | ||
|
|
||
| static SYSTICK: Mutex<RefCell<Option<SYST>>> = Mutex::new(RefCell::new(None)); | ||
| static WRAP_COUNT: AtomicU32 = AtomicU32::new(0); | ||
|
|
||
| #[exception] | ||
| fn SysTick() { | ||
| interrupt::free(|token| { | ||
| let mut systick_ref = SYSTICK.borrow(token).borrow_mut(); | ||
|
|
||
| let systick = systick_ref | ||
| .as_mut() | ||
| .expect("timer not initialized"); | ||
|
|
||
| if systick.has_wrapped() { | ||
| WRAP_COUNT.fetch_add(1, Ordering::Relaxed); | ||
| } | ||
| }) | ||
| } |