Implement the time module.

src/lib.rs

@@ -101,6 +101,7 @@ pub mod phy;
 pub mod wire;
 pub mod iface;
 pub mod socket;
+pub mod time;
 
 /// The error type for the networking stack.
 #[derive(Debug, Clone, Copy, PartialEq, Eq)]

src/time.rs

@@ -0,0 +1,299 @@
+/*! 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 represet relative time.
+
+[Instant]: struct.Instant.html
+[Duration]: struct.Duration.html
+*/
+
+use core::{ops, fmt};
+
+/// A representation of an absolute time value.
+///
+/// The `Instant` type is a wrapper around a `i64` value that
+/// represents a number of milliseconds, 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 {
+    millis: i64,
+}
+
+impl Instant {
+    /// Create a new `Instant` from a number of milliseconds.
+    pub fn from_millis(millis: i64) -> Instant {
+        Instant { millis }
+    }
+
+    /// Create a new `Instant` from the current `SystemTime`.
+    #[cfg(feature = "std")]
+    pub fn now() -> Result<Instant, ::std::time::SystemTimeError> {
+        Self::from_system_time(::std::time::SystemTime::now())
+    }
+
+    /// Create a new `Instant` from a `SystemTime`.
+    #[cfg(feature = "std")]
+    pub fn from_system_time(time: ::std::time::SystemTime) -> Result<Instant, ::std::time::SystemTimeError> {
+        let n = ::std::time::UNIX_EPOCH.duration_since(time)?;
+        Ok(Self::from_millis(n.as_secs() as i64 * 1000 + (n.subsec_nanos() / 1_000_000) as i64))
+    }
+
+    /// The fractional number of milliseconds that have passed
+    /// since the beginning of time.
+    pub fn millis(&self) -> i64 {
+        self.millis % 1000
+    }
+
+    /// The number of whole seconds that have passed since the
+    /// beginning of time.
+    pub fn secs(&self) -> i64 {
+        self.millis / 1000
+    }
+
+    /// The total number of milliseconds that have passed since
+    /// the biginning of time.
+    pub fn total_millis(&self) -> i64 {
+        self.millis
+    }
+}
+
+#[cfg(feature = "std")]
+impl Into<::std::time::SystemTime> for Instant {
+    fn into(self) -> ::std::time::SystemTime {
+        ::std::time::UNIX_EPOCH + ::std::time::Duration::from_millis(self.millis as u64)
+    }
+}
+
+impl fmt::Display for Instant {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        write!(f, "{}.{}s", self.secs(), self.millis())
+    }
+}
+
+impl ops::Add<Duration> for Instant {
+    type Output = Instant;
+
+    fn add(self, rhs: Duration) -> Instant {
+        Instant::from_millis(self.millis + rhs.total_millis() as i64)
+    }
+}
+
+impl ops::Sub<Duration> for Instant {
+    type Output = Instant;
+
+    fn sub(self, rhs: Duration) -> Instant {
+        Instant::from_millis(self.millis - rhs.total_millis() as i64)
+    }
+}
+
+/// A relative amount of time.
+#[derive(Debug, Copy, Clone, PartialEq, Eq, PartialOrd, Ord)]
+pub struct Duration {
+    millis: u64,
+}
+
+impl Duration {
+    /// Create a new `Duration` from a number of milliseconds.
+    pub fn from_millis(millis: u64) -> Duration {
+        Duration { millis }
+    }
+
+    /// The fractional number of milliseconds in this `Duration`.
+    pub fn millis(&self) -> u64 {
+        self.millis % 1000
+    }
+
+    /// The number of whole seconds in this `Duration`.
+    pub fn secs(&self) -> u64 {
+        self.millis / 1000
+    }
+
+    /// The total number of milliseconds in this `Duration`.
+    pub fn total_millis(&self) -> u64 {
+        self.millis
+    }
+}
+
+impl fmt::Display for Duration {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        write!(f, "{}.{}s", self.secs(), self.millis())
+    }
+}
+
+impl ops::Add<Duration> for Duration {
+    type Output = Duration;
+
+    fn add(self, rhs: Duration) -> Duration {
+        Duration::from_millis(self.millis + rhs.total_millis())
+    }
+}
+
+impl ops::AddAssign<Duration> for Duration {
+    fn add_assign(&mut self, rhs: Duration) {
+        self.millis += rhs.total_millis();
+    }
+}
+
+impl ops::Sub<Duration> for Duration {
+    type Output = Duration;
+
+    fn sub(self, rhs: Duration) -> Duration {
+        Duration::from_millis(
+            self.millis.checked_sub(rhs.total_millis()).expect("overflow when subtracting durations"))
+    }
+}
+
+impl ops::SubAssign<Duration> for Duration {
+    fn sub_assign(&mut self, rhs: Duration) {
+        self.millis = self.millis.checked_sub(
+            rhs.total_millis()).expect("overflow when subtracting durations");
+    }
+}
+
+impl ops::Mul<u32> for Duration {
+    type Output = Duration;
+
+    fn mul(self, rhs: u32) -> Duration {
+        Duration::from_millis(self.millis * rhs as u64)
+    }
+}
+
+impl ops::MulAssign<u32> for Duration {
+    fn mul_assign(&mut self, rhs: u32) {
+        self.millis *= rhs as u64;
+    }
+}
+
+impl ops::Div<u32> for Duration {
+    type Output = Duration;
+
+    fn div(self, rhs: u32) -> Duration {
+        Duration::from_millis(self.millis / rhs as u64)
+    }
+}
+
+impl ops::DivAssign<u32> for Duration {
+    fn div_assign(&mut self, rhs: u32) {
+        self.millis /= rhs as u64;
+    }
+}
+
+#[cfg(feature = "std")]
+impl From<::std::time::Duration> for Duration {
+    fn from(other: ::std::time::Duration) -> Duration {
+        Duration::from_millis(
+            other.as_secs() * 1000 + (other.subsec_nanos() / 1_000_000) as u64
+        )
+    }
+}
+
+#[cfg(feature = "std")]
+impl Into<::std::time::Duration> for Duration {
+    fn into(self) -> ::std::time::Duration {
+        ::std::time::Duration::from_millis(
+            self.total_millis()
+        )
+    }
+}
+
+#[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(5674)), "5.674s");
+        assert_eq!(format!("{}", Instant::from_millis(5000)), "5.0s");
+    }
+
+    #[test]
+    #[cfg(feature = "std")]
+    fn test_instant_conversions() {
+        let mut epoc: ::std::time::SystemTime = Instant::from_millis(0).into();
+        assert_eq!(Instant::from_system_time(::std::time::UNIX_EPOCH).unwrap(),
+                   Instant::from_millis(0));
+        assert_eq!(epoc, ::std::time::UNIX_EPOCH);
+        epoc = Instant::from_millis(2085955200 * 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_millis(13));
+    }
+
+    #[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_millis(4187));
+    }
+
+    #[test]
+    #[should_panic(expected = "overflow when subtracting durations")]
+    fn test_sub_from_zero_overflow() {
+        Duration::from_millis(0) - Duration::from_millis(1);
+    }
+
+    #[test]
+    #[should_panic(expected = "attempt to divide by zero")]
+    fn test_div_by_zero() {
+        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]
+    #[cfg(feature = "std")]
+    fn test_duration_conversions() {
+        let mut std_duration = ::std::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, ::std::time::Duration::from_millis(4934));
+    }
+}