time: Add time module from stm32h7xx-hal

Author: astapleton

src/lib.rs

@@ -42,3 +42,6 @@ pub mod prelude;
 
 #[cfg(feature = "device-selected")]
 pub mod pwr;
+
+#[cfg(feature = "device-selected")]
+pub mod time;

src/time.rs

@@ -0,0 +1,38 @@
+//! Time units
+
+pub use fugit::{
+    HertzU32 as Hertz, KilohertzU32 as KiloHertz, MegahertzU32 as MegaHertz,
+    MicrosDurationU32 as MicroSeconds, MillisDurationU32 as MilliSeconds,
+    NanosDurationU32 as NanoSeconds,
+};
+
+//use core::time::Duration;
+use cortex_m::peripheral::DWT;
+
+/// Bits per second
+pub type Bps = Hertz;
+
+/// Extension trait that adds convenience methods to the `u32` type
+pub trait U32Ext {
+    /// Wrap in `Bps`
+    fn bps(self) -> Bps;
+}
+
+impl U32Ext for u32 {
+    fn bps(self) -> Bps {
+        Bps::from_raw(self)
+    }
+}
+
+/// A measurement of a monotonically nondecreasing clock
+#[derive(Clone, Copy)]
+pub struct Instant {
+    now: u32,
+}
+
+impl Instant {
+    /// Ticks elapsed since the `Instant` was created
+    pub fn elapsed(&self) -> u32 {
+        DWT::cycle_count().wrapping_sub(self.now)
+    }
+}