Merge pull request #178 from flipperzero-rs/fix-duration-max

Fix `flipperzero::furi::time::Duration::MAX`

Author: dcoles

CHANGELOG.md

@@ -14,6 +14,7 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.1.0/).
 ### Changed
 
 - `flipperzero::dialogs::DialogFileBrowserOptions` now uses native initialization function.
+- `flipperzero::time::Duration::MAX` is now the maximum duration representable.
 
 ### Removed
 

crates/flipperzero/src/furi/time.rs

@@ -5,9 +5,8 @@ use core::ops::{Add, AddAssign, Div, DivAssign, Mul, MulAssign, Sub, SubAssign};
 use flipperzero_sys as sys;
 use ufmt::derive::uDebug;
 
-/// The maximum number of ticks that a [`Duration`] can contain for it to be usable with
-/// [`Instant`].
-const MAX_DURATION_TICKS: u32 = u32::MAX / 2;
+/// Maximum number of ticks a [`Duration`] can contain to be usable with [`Instant`].
+const MAX_INTERVAL_DURATION_TICKS: u32 = u32::MAX / 2;
 
 const NANOS_PER_SEC_F: f64 = 1_000_000_000_f64;
 const NANOS_PER_SEC: u64 = 1_000_000_000;
@@ -102,7 +101,7 @@ impl Instant {
     /// represented as `Instant` (which means it's inside the bounds of the underlying
     /// data structure), `None` otherwise.
     pub fn checked_add(&self, duration: Duration) -> Option<Instant> {
-        if duration.0 <= MAX_DURATION_TICKS {
+        if duration.0 <= MAX_INTERVAL_DURATION_TICKS {
             Some(Instant(self.0.wrapping_add(duration.0)))
         } else {
             None
@@ -113,7 +112,7 @@ impl Instant {
     /// represented as `Instant` (which means it's inside the bounds of the underlying
     /// data structure), `None` otherwise.
     pub fn checked_sub(&self, duration: Duration) -> Option<Instant> {
-        if duration.0 <= MAX_DURATION_TICKS {
+        if duration.0 <= MAX_INTERVAL_DURATION_TICKS {
             Some(Instant(self.0.wrapping_sub(duration.0)))
         } else {
             None
@@ -134,10 +133,10 @@ impl Ord for Instant {
             Ordering::Equal
         } else {
             // We use modular arithmetic to define ordering.
-            // This requires a maximum `Duration` value of `MAX_DURATION_TICKS`.
+            // This requires a maximum `Duration` value of `MAX_INTERVAL_DURATION_TICKS`.
             self.0
                 .wrapping_sub(other.0)
-                .cmp(&MAX_DURATION_TICKS)
+                .cmp(&MAX_INTERVAL_DURATION_TICKS)
                 .reverse()
         }
     }
@@ -195,7 +194,7 @@ impl Sub<Instant> for Instant {
 ///
 /// Each `Duration` is composed of a whole number of "ticks", the length of which depends
 /// on the firmware's tick frequency. While a `Duration` can contain any value that
-/// is at most [`u32::MAX`] ticks, only the range `[Duration::ZERO..=DURATION::MAX]` can
+/// is at most [`u32::MAX`] ticks, only the range `[Duration::ZERO..=DURATION::MAX/2]` can
 /// be used with [`Instant`].
 #[derive(Clone, Copy, Debug, uDebug, Default, PartialEq, Eq, PartialOrd, Ord, Hash)]
 pub struct Duration(pub(super) u32);
@@ -209,7 +208,7 @@ impl Duration {
     /// May vary by platform as necessary. Must be able to contain the difference between
     /// two instances of [`Instant`]. This constraint gives it a value of about 24 days in
     /// practice on stock firmware.
-    pub const MAX: Duration = Duration(MAX_DURATION_TICKS);
+    pub const MAX: Duration = Duration(u32::MAX);
 
     /// Creates a new `Duration` from the specified number of whole seconds.
     ///
@@ -467,7 +466,7 @@ impl<'a> Sum<&'a Duration> for Duration {
 
 #[flipperzero_test::tests]
 mod tests {
-    use super::{ticks_to_ns, Duration, Instant, MAX_DURATION_TICKS};
+    use super::{ticks_to_ns, Duration, Instant, MAX_INTERVAL_DURATION_TICKS};
     use crate::println;
 
     #[cfg(feature = "alloc")]
@@ -607,7 +606,8 @@ mod tests {
             start: Option<T>,
             op: impl Fn(&T, Duration) -> Option<T>,
         ) {
-            const DURATIONS: [Duration; 2] = [Duration(MAX_DURATION_TICKS >> 1), Duration(50)];
+            const DURATIONS: [Duration; 2] =
+                [Duration(MAX_INTERVAL_DURATION_TICKS >> 1), Duration(50)];
             if let Some(start) = start {
                 assert_eq!(
                     op(&start, DURATIONS.into_iter().sum()),