Struct WaitTimer 

pub struct WaitTimer(/* private fields */);

Available on crate feature nano-alloc only.

A high-precision asynchronous timer based on hardware ticks.

WaitTimer leverages the CPU’s Time Stamp Counter (TSC) to provide non-blocking delays ranging from picoseconds to years. It implements the Future trait, allowing the executor to suspend tasks until the specified hardware deadline is reached.

Precision and Accuracy

The timer relies on the calibrated frequency stored in FREQ. Accuracy is determined by the sampling quality during init_clock_freq().

Examples

Using the builder-style methods:

async fn delay_example() {
    // Create a timer for 500 milliseconds
    WaitTimer::from_ms(500).await;
}

Using the _WaitTimer extension trait for a more expressive DSL:

use uefi_async::nano_alloc::time::{WaitTimer, _WaitTimer};

async fn blink_led_task() {
    loop {
        // Highly readable duration syntax
        1.s().await;        // Wait 1 second
        500.ms().await;     // Wait 500 milliseconds
        20.fps().await;     // Wait for 1 frame duration at 20 FPS (50ms)

        // Precise sub-microsecond timing
        10.us().await;      // 10 microseconds
        80.ps().await;      // 80 picoseconds (Note: Dependent on CPU Ghz)

        // Long-term scheduling
        2.hour().await;
        1.day().await;
    }
}

Implementations

impl WaitTimer

pub fn until(deadline: u64) -> Self

Constructs a timer that expires at an absolute hardware tick count.

pub fn after(ticks_to_wait: u64) -> Self

Constructs a timer that expires after a relative number of ticks from now.

pub fn is_expired(&self) -> bool

Checks if the current hardware tick has reached or exceeded the deadline.

This uses a direct comparison, assuming the timer is polled frequently enough to handle 64-bit tick overflows (which take centuries on modern CPUs).

pub fn from_year(y: u64) -> Self

pub fn from_month(m: u64) -> Self

pub fn from_week(w: u64) -> Self

pub fn from_day(d: u64) -> Self

pub fn from_hour(h: u64) -> Self

pub fn from_min(min: u64) -> Self

pub fn from_s(hz: u64) -> Self

pub fn from_ms(ms: u64) -> Self

pub fn from_us(us: u64) -> Self

pub fn from_ns(ns: u64) -> Self

pub fn from_ps(ps: u64) -> Self

pub fn from_fps(fps: u64) -> Self

Trait Implementations

impl Debug for WaitTimer

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Future for WaitTimer

type Output = ()

The type of value produced on completion.

fn poll(self: Pin<&mut Self>, _: &mut Context<'_>) -> Poll<Self::Output>

Attempts to resolve the future to a final value, registering the current task for wakeup if the value is not yet available.