std: xous: add support for time

Add support for determining the current time. This connects to the
ticktimer server in order to get the system uptime.

Signed-off-by: Sean Cross <sean@xobs.io>

library/std/src/sys/xous/mod.rs

@@ -33,7 +33,6 @@ pub mod thread;
 pub mod thread_local_key;
 #[path = "../unsupported/thread_parking.rs"]
 pub mod thread_parking;
-#[path = "../unsupported/time.rs"]
 pub mod time;
 
 #[path = "../unsupported/common.rs"]

library/std/src/sys/xous/time.rs

@@ -0,0 +1,57 @@
+use crate::os::xous::ffi::blocking_scalar;
+use crate::os::xous::services::{
+    systime_server, ticktimer_server, SystimeScalar::GetUtcTimeMs, TicktimerScalar::ElapsedMs,
+};
+use crate::time::Duration;
+
+#[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Debug, Hash)]
+pub struct Instant(Duration);
+
+#[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Debug, Hash)]
+pub struct SystemTime(Duration);
+
+pub const UNIX_EPOCH: SystemTime = SystemTime(Duration::from_secs(0));
+
+impl Instant {
+    pub fn now() -> Instant {
+        let result = blocking_scalar(ticktimer_server(), ElapsedMs.into())
+            .expect("failed to request elapsed_ms");
+        let lower = result[0];
+        let upper = result[1];
+        Instant { 0: Duration::from_millis(lower as u64 | (upper as u64) << 32) }
+    }
+
+    pub fn checked_sub_instant(&self, other: &Instant) -> Option<Duration> {
+        self.0.checked_sub(other.0)
+    }
+
+    pub fn checked_add_duration(&self, other: &Duration) -> Option<Instant> {
+        self.0.checked_add(*other).map(Instant)
+    }
+
+    pub fn checked_sub_duration(&self, other: &Duration) -> Option<Instant> {
+        self.0.checked_sub(*other).map(Instant)
+    }
+}
+
+impl SystemTime {
+    pub fn now() -> SystemTime {
+        let result = blocking_scalar(systime_server(), GetUtcTimeMs.into())
+            .expect("failed to request utc time in ms");
+        let lower = result[0];
+        let upper = result[1];
+        SystemTime { 0: Duration::from_millis((upper as u64) << 32 | lower as u64) }
+    }
+
+    pub fn sub_time(&self, other: &SystemTime) -> Result<Duration, Duration> {
+        self.0.checked_sub(other.0).ok_or_else(|| other.0 - self.0)
+    }
+
+    pub fn checked_add_duration(&self, other: &Duration) -> Option<SystemTime> {
+        Some(SystemTime(self.0.checked_add(*other)?))
+    }
+
+    pub fn checked_sub_duration(&self, other: &Duration) -> Option<SystemTime> {
+        Some(SystemTime(self.0.checked_sub(*other)?))
+    }
+}