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use super::{abi, error::expect_success};
use crate::{mem::MaybeUninit, time::Duration};
#[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Debug, Hash)]
pub struct Instant(abi::SYSTIM);
impl Instant {
pub fn now() -> Instant {
// Safety: The provided pointer is valid
unsafe {
let mut out = MaybeUninit::uninit();
expect_success(abi::get_tim(out.as_mut_ptr()), &"get_tim");
Instant(out.assume_init())
}
}
pub fn checked_sub_instant(&self, other: &Instant) -> Option<Duration> {
self.0.checked_sub(other.0).map(|ticks| {
// `SYSTIM` is measured in microseconds
Duration::from_micros(ticks)
})
}
pub fn checked_add_duration(&self, other: &Duration) -> Option<Instant> {
// `SYSTIM` is measured in microseconds
let ticks = other.as_micros();
Some(Instant(self.0.checked_add(ticks.try_into().ok()?)?))
}
pub fn checked_sub_duration(&self, other: &Duration) -> Option<Instant> {
// `SYSTIM` is measured in microseconds
let ticks = other.as_micros();
Some(Instant(self.0.checked_sub(ticks.try_into().ok()?)?))
}
}
/// Split `Duration` into zero or more `RELTIM`s.
#[inline]
pub fn dur2reltims(dur: Duration) -> impl Iterator<Item = abi::RELTIM> {
// `RELTIM` is microseconds
let mut ticks = dur.as_micros();
crate::iter::from_fn(move || {
if ticks == 0 {
None
} else if ticks <= abi::TMAX_RELTIM as u128 {
Some(crate::mem::replace(&mut ticks, 0) as abi::RELTIM)
} else {
ticks -= abi::TMAX_RELTIM as u128;
Some(abi::TMAX_RELTIM)
}
})
}
/// Split `Duration` into one or more `TMO`s.
#[inline]
fn dur2tmos(dur: Duration) -> impl Iterator<Item = abi::TMO> {
// `TMO` is microseconds
let mut ticks = dur.as_micros();
let mut end = false;
crate::iter::from_fn(move || {
if end {
None
} else if ticks <= abi::TMAX_RELTIM as u128 {
end = true;
Some(crate::mem::replace(&mut ticks, 0) as abi::TMO)
} else {
ticks -= abi::TMAX_RELTIM as u128;
Some(abi::TMAX_RELTIM)
}
})
}
/// Split `Duration` into one or more API calls with timeout.
#[inline]
pub fn with_tmos(dur: Duration, mut f: impl FnMut(abi::TMO) -> abi::ER) -> abi::ER {
let mut er = abi::E_TMOUT;
for tmo in dur2tmos(dur) {
er = f(tmo);
if er != abi::E_TMOUT {
break;
}
}
er
}
/// Split `Duration` into one or more API calls with timeout. This function can
/// handle spurious wakeups.
#[inline]
pub fn with_tmos_strong(dur: Duration, mut f: impl FnMut(abi::TMO) -> abi::ER) -> abi::ER {
// `TMO` and `SYSTIM` are microseconds.
// Clamp at `SYSTIM::MAX` for performance reasons. This shouldn't cause
// a problem in practice. (`u64::MAX` μs ≈ 584942 years)
let ticks = dur.as_micros().min(abi::SYSTIM::MAX as u128) as abi::SYSTIM;
let start = Instant::now().0;
let mut elapsed = 0;
let mut er = abi::E_TMOUT;
while elapsed <= ticks {
er = f(elapsed.min(abi::TMAX_RELTIM as abi::SYSTIM) as abi::TMO);
if er != abi::E_TMOUT {
break;
}
elapsed = Instant::now().0.wrapping_sub(start);
}
er
}
#[cfg(test)]
mod tests;
|
