1 files changed, 460 insertions, 0 deletions
diff --git a/src/time.rs b/src/time.rs
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+++ b/src/time.rs
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+/*! Time structures.
+
+The `time` module contains structures used to represent both
+absolute and relative time.
+
+ - [Instant] is used to represent absolute time.
+ - [Duration] is used to represent relative time.
+
+[Instant]: struct.Instant.html
+[Duration]: struct.Duration.html
+*/
+
+use core::{fmt, ops};
+
+/// A representation of an absolute time value.
+///
+/// The `Instant` type is a wrapper around a `i64` value that
+/// represents a number of microseconds, monotonically increasing
+/// since an arbitrary moment in time, such as system startup.
+///
+/// * A value of `0` is inherently arbitrary.
+/// * A value less than `0` indicates a time before the starting
+///   point.
+#[derive(Debug, Copy, Clone, PartialEq, Eq, PartialOrd, Ord)]
+pub struct Instant {
+    micros: i64,
+}
+
+impl Instant {
+    pub const ZERO: Instant = Instant::from_micros_const(0);
+
+    /// Create a new `Instant` from a number of microseconds.
+    pub fn from_micros<T: Into<i64>>(micros: T) -> Instant {
+        Instant {
+            micros: micros.into(),
+        }
+    }
+
+    pub const fn from_micros_const(micros: i64) -> Instant {
+        Instant { micros }
+    }
+
+    /// Create a new `Instant` from a number of milliseconds.
+    pub fn from_millis<T: Into<i64>>(millis: T) -> Instant {
+        Instant {
+            micros: millis.into() * 1000,
+        }
+    }
+
+    /// Create a new `Instant` from a number of milliseconds.
+    pub const fn from_millis_const(millis: i64) -> Instant {
+        Instant {
+            micros: millis * 1000,
+        }
+    }
+
+    /// Create a new `Instant` from a number of seconds.
+    pub fn from_secs<T: Into<i64>>(secs: T) -> Instant {
+        Instant {
+            micros: secs.into() * 1000000,
+        }
+    }
+
+    /// Create a new `Instant` from the current [std::time::SystemTime].
+    ///
+    /// See [std::time::SystemTime::now]
+    ///
+    /// [std::time::SystemTime]: https://doc.rust-lang.org/std/time/struct.SystemTime.html
+    /// [std::time::SystemTime::now]: https://doc.rust-lang.org/std/time/struct.SystemTime.html#method.now
+    #[cfg(feature = "std")]
+    pub fn now() -> Instant {
+        Self::from(::std::time::SystemTime::now())
+    }
+
+    /// The fractional number of milliseconds that have passed
+    /// since the beginning of time.
+    pub const fn millis(&self) -> i64 {
+        self.micros % 1000000 / 1000
+    }
+
+    /// The fractional number of microseconds that have passed
+    /// since the beginning of time.
+    pub const fn micros(&self) -> i64 {
+        self.micros % 1000000
+    }
+
+    /// The number of whole seconds that have passed since the
+    /// beginning of time.
+    pub const fn secs(&self) -> i64 {
+        self.micros / 1000000
+    }
+
+    /// The total number of milliseconds that have passed since
+    /// the beginning of time.
+    pub const fn total_millis(&self) -> i64 {
+        self.micros / 1000
+    }
+    /// The total number of milliseconds that have passed since
+    /// the beginning of time.
+    pub const fn total_micros(&self) -> i64 {
+        self.micros
+    }
+}
+
+#[cfg(feature = "std")]
+impl From<::std::time::Instant> for Instant {
+    fn from(other: ::std::time::Instant) -> Instant {
+        let elapsed = other.elapsed();
+        Instant::from_micros((elapsed.as_secs() * 1_000000) as i64 + elapsed.subsec_micros() as i64)
+    }
+}
+
+#[cfg(feature = "std")]
+impl From<::std::time::SystemTime> for Instant {
+    fn from(other: ::std::time::SystemTime) -> Instant {
+        let n = other
+            .duration_since(::std::time::UNIX_EPOCH)
+            .expect("start time must not be before the unix epoch");
+        Self::from_micros(n.as_secs() as i64 * 1000000 + n.subsec_micros() as i64)
+    }
+}
+
+#[cfg(feature = "std")]
+impl From<Instant> for ::std::time::SystemTime {
+    fn from(val: Instant) -> Self {
+        ::std::time::UNIX_EPOCH + ::std::time::Duration::from_micros(val.micros as u64)
+    }
+}
+
+impl fmt::Display for Instant {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        write!(f, "{}.{:0>3}s", self.secs(), self.millis())
+    }
+}
+
+#[cfg(feature = "defmt")]
+impl defmt::Format for Instant {
+    fn format(&self, f: defmt::Formatter) {
+        defmt::write!(f, "{}.{:03}s", self.secs(), self.millis());
+    }
+}
+
+impl ops::Add<Duration> for Instant {
+    type Output = Instant;
+
+    fn add(self, rhs: Duration) -> Instant {
+        Instant::from_micros(self.micros + rhs.total_micros() as i64)
+    }
+}
+
+impl ops::AddAssign<Duration> for Instant {
+    fn add_assign(&mut self, rhs: Duration) {
+        self.micros += rhs.total_micros() as i64;
+    }
+}
+
+impl ops::Sub<Duration> for Instant {
+    type Output = Instant;
+
+    fn sub(self, rhs: Duration) -> Instant {
+        Instant::from_micros(self.micros - rhs.total_micros() as i64)
+    }
+}
+
+impl ops::SubAssign<Duration> for Instant {
+    fn sub_assign(&mut self, rhs: Duration) {
+        self.micros -= rhs.total_micros() as i64;
+    }
+}
+
+impl ops::Sub<Instant> for Instant {
+    type Output = Duration;
+
+    fn sub(self, rhs: Instant) -> Duration {
+        Duration::from_micros((self.micros - rhs.micros).unsigned_abs())
+    }
+}
+
+/// A relative amount of time.
+#[derive(Debug, Default, Copy, Clone, PartialEq, Eq, PartialOrd, Ord)]
+pub struct Duration {
+    micros: u64,
+}
+
+impl Duration {
+    pub const ZERO: Duration = Duration::from_micros(0);
+    /// The longest possible duration we can encode.
+    pub const MAX: Duration = Duration::from_micros(u64::MAX);
+    /// Create a new `Duration` from a number of microseconds.
+    pub const fn from_micros(micros: u64) -> Duration {
+        Duration { micros }
+    }
+
+    /// Create a new `Duration` from a number of milliseconds.
+    pub const fn from_millis(millis: u64) -> Duration {
+        Duration {
+            micros: millis * 1000,
+        }
+    }
+
+    /// Create a new `Instant` from a number of seconds.
+    pub const fn from_secs(secs: u64) -> Duration {
+        Duration {
+            micros: secs * 1000000,
+        }
+    }
+
+    /// The fractional number of milliseconds in this `Duration`.
+    pub const fn millis(&self) -> u64 {
+        self.micros / 1000 % 1000
+    }
+
+    /// The fractional number of milliseconds in this `Duration`.
+    pub const fn micros(&self) -> u64 {
+        self.micros % 1000000
+    }
+
+    /// The number of whole seconds in this `Duration`.
+    pub const fn secs(&self) -> u64 {
+        self.micros / 1000000
+    }
+
+    /// The total number of milliseconds in this `Duration`.
+    pub const fn total_millis(&self) -> u64 {
+        self.micros / 1000
+    }
+
+    /// The total number of microseconds in this `Duration`.
+    pub const fn total_micros(&self) -> u64 {
+        self.micros
+    }
+}
+
+impl fmt::Display for Duration {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        write!(f, "{}.{:03}s", self.secs(), self.millis())
+    }
+}
+
+#[cfg(feature = "defmt")]
+impl defmt::Format for Duration {
+    fn format(&self, f: defmt::Formatter) {
+        defmt::write!(f, "{}.{:03}s", self.secs(), self.millis());
+    }
+}
+
+impl ops::Add<Duration> for Duration {
+    type Output = Duration;
+
+    fn add(self, rhs: Duration) -> Duration {
+        Duration::from_micros(self.micros + rhs.total_micros())
+    }
+}
+
+impl ops::AddAssign<Duration> for Duration {
+    fn add_assign(&mut self, rhs: Duration) {
+        self.micros += rhs.total_micros();
+    }
+}
+
+impl ops::Sub<Duration> for Duration {
+    type Output = Duration;
+
+    fn sub(self, rhs: Duration) -> Duration {
+        Duration::from_micros(
+            self.micros
+                .checked_sub(rhs.total_micros())
+                .expect("overflow when subtracting durations"),
+        )
+    }
+}
+
+impl ops::SubAssign<Duration> for Duration {
+    fn sub_assign(&mut self, rhs: Duration) {
+        self.micros = self
+            .micros
+            .checked_sub(rhs.total_micros())
+            .expect("overflow when subtracting durations");
+    }
+}
+
+impl ops::Mul<u32> for Duration {
+    type Output = Duration;
+
+    fn mul(self, rhs: u32) -> Duration {
+        Duration::from_micros(self.micros * rhs as u64)
+    }
+}
+
+impl ops::MulAssign<u32> for Duration {
+    fn mul_assign(&mut self, rhs: u32) {
+        self.micros *= rhs as u64;
+    }
+}
+
+impl ops::Div<u32> for Duration {
+    type Output = Duration;
+
+    fn div(self, rhs: u32) -> Duration {
+        Duration::from_micros(self.micros / rhs as u64)
+    }
+}
+
+impl ops::DivAssign<u32> for Duration {
+    fn div_assign(&mut self, rhs: u32) {
+        self.micros /= rhs as u64;
+    }
+}
+
+impl ops::Shl<u32> for Duration {
+    type Output = Duration;
+
+    fn shl(self, rhs: u32) -> Duration {
+        Duration::from_micros(self.micros << rhs)
+    }
+}
+
+impl ops::ShlAssign<u32> for Duration {
+    fn shl_assign(&mut self, rhs: u32) {
+        self.micros <<= rhs;
+    }
+}
+
+impl ops::Shr<u32> for Duration {
+    type Output = Duration;
+
+    fn shr(self, rhs: u32) -> Duration {
+        Duration::from_micros(self.micros >> rhs)
+    }
+}
+
+impl ops::ShrAssign<u32> for Duration {
+    fn shr_assign(&mut self, rhs: u32) {
+        self.micros >>= rhs;
+    }
+}
+
+impl From<::core::time::Duration> for Duration {
+    fn from(other: ::core::time::Duration) -> Duration {
+        Duration::from_micros(other.as_secs() * 1000000 + other.subsec_micros() as u64)
+    }
+}
+
+impl From<Duration> for ::core::time::Duration {
+    fn from(val: Duration) -> Self {
+        ::core::time::Duration::from_micros(val.total_micros())
+    }
+}
+
+#[cfg(test)]
+mod test {
+    use super::*;
+
+    #[test]
+    fn test_instant_ops() {
+        // std::ops::Add
+        assert_eq!(
+            Instant::from_millis(4) + Duration::from_millis(6),
+            Instant::from_millis(10)
+        );
+        // std::ops::Sub
+        assert_eq!(
+            Instant::from_millis(7) - Duration::from_millis(5),
+            Instant::from_millis(2)
+        );
+    }
+
+    #[test]
+    fn test_instant_getters() {
+        let instant = Instant::from_millis(5674);
+        assert_eq!(instant.secs(), 5);
+        assert_eq!(instant.millis(), 674);
+        assert_eq!(instant.total_millis(), 5674);
+    }
+
+    #[test]
+    fn test_instant_display() {
+        assert_eq!(format!("{}", Instant::from_millis(74)), "0.074s");
+        assert_eq!(format!("{}", Instant::from_millis(5674)), "5.674s");
+        assert_eq!(format!("{}", Instant::from_millis(5000)), "5.000s");
+    }
+
+    #[test]
+    #[cfg(feature = "std")]
+    fn test_instant_conversions() {
+        let mut epoc: ::std::time::SystemTime = Instant::from_millis(0).into();
+        assert_eq!(
+            Instant::from(::std::time::UNIX_EPOCH),
+            Instant::from_millis(0)
+        );
+        assert_eq!(epoc, ::std::time::UNIX_EPOCH);
+        epoc = Instant::from_millis(2085955200i64 * 1000).into();
+        assert_eq!(
+            epoc,
+            ::std::time::UNIX_EPOCH + ::std::time::Duration::from_secs(2085955200)
+        );
+    }
+
+    #[test]
+    fn test_duration_ops() {
+        // std::ops::Add
+        assert_eq!(
+            Duration::from_millis(40) + Duration::from_millis(2),
+            Duration::from_millis(42)
+        );
+        // std::ops::Sub
+        assert_eq!(
+            Duration::from_millis(555) - Duration::from_millis(42),
+            Duration::from_millis(513)
+        );
+        // std::ops::Mul
+        assert_eq!(Duration::from_millis(13) * 22, Duration::from_millis(286));
+        // std::ops::Div
+        assert_eq!(Duration::from_millis(53) / 4, Duration::from_micros(13250));
+    }
+
+    #[test]
+    fn test_duration_assign_ops() {
+        let mut duration = Duration::from_millis(4735);
+        duration += Duration::from_millis(1733);
+        assert_eq!(duration, Duration::from_millis(6468));
+        duration -= Duration::from_millis(1234);
+        assert_eq!(duration, Duration::from_millis(5234));
+        duration *= 4;
+        assert_eq!(duration, Duration::from_millis(20936));
+        duration /= 5;
+        assert_eq!(duration, Duration::from_micros(4187200));
+    }
+
+    #[test]
+    #[should_panic(expected = "overflow when subtracting durations")]
+    fn test_sub_from_zero_overflow() {
+        let _ = Duration::from_millis(0) - Duration::from_millis(1);
+    }
+
+    #[test]
+    #[should_panic(expected = "attempt to divide by zero")]
+    fn test_div_by_zero() {
+        let _ = Duration::from_millis(4) / 0;
+    }
+
+    #[test]
+    fn test_duration_getters() {
+        let instant = Duration::from_millis(4934);
+        assert_eq!(instant.secs(), 4);
+        assert_eq!(instant.millis(), 934);
+        assert_eq!(instant.total_millis(), 4934);
+    }
+
+    #[test]
+    fn test_duration_conversions() {
+        let mut std_duration = ::core::time::Duration::from_millis(4934);
+        let duration: Duration = std_duration.into();
+        assert_eq!(duration, Duration::from_millis(4934));
+        assert_eq!(Duration::from(std_duration), Duration::from_millis(4934));
+
+        std_duration = duration.into();
+        assert_eq!(std_duration, ::core::time::Duration::from_millis(4934));
+    }
+}