axplat/
time.rs

1//! Time-related operations.
2
3pub use core::time::Duration;
4
5/// A measurement of the system clock.
6///
7/// Currently, it reuses the [`core::time::Duration`] type. But it does not
8/// represent a duration, but a clock time.
9pub type TimeValue = Duration;
10
11/// Number of milliseconds in a second.
12pub const MILLIS_PER_SEC: u64 = 1_000;
13/// Number of microseconds in a second.
14pub const MICROS_PER_SEC: u64 = 1_000_000;
15/// Number of nanoseconds in a second.
16pub const NANOS_PER_SEC: u64 = 1_000_000_000;
17/// Number of nanoseconds in a millisecond.
18pub const NANOS_PER_MILLIS: u64 = 1_000_000;
19/// Number of nanoseconds in a microsecond.
20pub const NANOS_PER_MICROS: u64 = 1_000;
21
22/// Time-related interfaces.
23#[def_plat_interface]
24pub trait TimeIf {
25    /// Returns the current clock time in hardware ticks.
26    fn current_ticks() -> u64;
27
28    /// Converts hardware ticks to nanoseconds.
29    fn ticks_to_nanos(ticks: u64) -> u64;
30
31    /// Converts nanoseconds to hardware ticks.
32    fn nanos_to_ticks(nanos: u64) -> u64;
33
34    /// Return epoch offset in nanoseconds (wall time offset to monotonic
35    /// clock start).
36    fn epochoffset_nanos() -> u64;
37
38    /// Set a one-shot timer.
39    ///
40    /// A timer interrupt will be triggered at the specified monotonic time
41    /// deadline (in nanoseconds).
42    fn set_oneshot_timer(deadline_ns: u64);
43}
44
45/// Returns nanoseconds elapsed since system boot.
46pub fn monotonic_time_nanos() -> u64 {
47    ticks_to_nanos(current_ticks())
48}
49
50/// Returns the time elapsed since system boot in [`TimeValue`].
51pub fn monotonic_time() -> TimeValue {
52    TimeValue::from_nanos(monotonic_time_nanos())
53}
54
55/// Returns nanoseconds elapsed since epoch (also known as realtime).
56pub fn wall_time_nanos() -> u64 {
57    monotonic_time_nanos() + epochoffset_nanos()
58}
59
60/// Returns the time elapsed since epoch (also known as realtime) in [`TimeValue`].
61pub fn wall_time() -> TimeValue {
62    TimeValue::from_nanos(monotonic_time_nanos() + epochoffset_nanos())
63}
64
65/// Busy waiting for the given duration.
66pub fn busy_wait(dur: Duration) {
67    busy_wait_until(wall_time() + dur);
68}
69
70/// Busy waiting until reaching the given deadline.
71pub fn busy_wait_until(deadline: TimeValue) {
72    while wall_time() < deadline {
73        core::hint::spin_loop();
74    }
75}
axplat/time.rs

axplat/
time.rs
