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Message-ID: <20241025033118.44452-4-fujita.tomonori@gmail.com>
Date: Fri, 25 Oct 2024 12:31:14 +0900
From: FUJITA Tomonori <fujita.tomonori@...il.com>
To: anna-maria@...utronix.de,
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Subject: [PATCH v4 3/7] rust: time: Introduce Instant type
Introduce a type representing a specific point in time. We could use
the Ktime type but C's ktime_t is used for both timestamp and
timedelta. To avoid confusion, introduce a new Instant type for
timestamp.
Rename Ktime to Instant and modify their methods for timestamp.
Implement the subtraction operator for Instant:
Delta = Instant A - Instant B
The operation never overflows (Instant ranges from 0 to
`KTIME_MAX`).
Signed-off-by: FUJITA Tomonori <fujita.tomonori@...il.com>
---
rust/kernel/time.rs | 48 +++++++++++++++------------------------------
1 file changed, 16 insertions(+), 32 deletions(-)
diff --git a/rust/kernel/time.rs b/rust/kernel/time.rs
index 574e72d3956b..3cc1a8a76777 100644
--- a/rust/kernel/time.rs
+++ b/rust/kernel/time.rs
@@ -31,59 +31,43 @@ pub fn msecs_to_jiffies(msecs: Msecs) -> Jiffies {
unsafe { bindings::__msecs_to_jiffies(msecs) }
}
-/// A Rust wrapper around a `ktime_t`.
+/// A specific point in time.
#[repr(transparent)]
#[derive(Copy, Clone, PartialEq, PartialOrd, Eq, Ord)]
-pub struct Ktime {
+pub struct Instant {
+ // Range from 0 to `KTIME_MAX`.
inner: bindings::ktime_t,
}
-impl Ktime {
- /// Create a `Ktime` from a raw `ktime_t`.
+impl Instant {
+ /// Create a `Instant` from a raw `ktime_t`.
#[inline]
- pub fn from_raw(inner: bindings::ktime_t) -> Self {
+ fn from_raw(inner: bindings::ktime_t) -> Self {
Self { inner }
}
/// Get the current time using `CLOCK_MONOTONIC`.
#[inline]
- pub fn ktime_get() -> Self {
+ pub fn now() -> Self {
// SAFETY: It is always safe to call `ktime_get` outside of NMI context.
Self::from_raw(unsafe { bindings::ktime_get() })
}
- /// Divide the number of nanoseconds by a compile-time constant.
#[inline]
- fn divns_constant<const DIV: i64>(self) -> i64 {
- self.to_ns() / DIV
- }
-
- /// Returns the number of nanoseconds.
- #[inline]
- pub fn to_ns(self) -> i64 {
- self.inner
- }
-
- /// Returns the number of milliseconds.
- #[inline]
- pub fn to_ms(self) -> i64 {
- self.divns_constant::<NSEC_PER_MSEC>()
+ /// Return the amount of time elapsed since the `Instant`.
+ pub fn elapsed(&self) -> Delta {
+ Self::now() - *self
}
}
-/// Returns the number of milliseconds between two ktimes.
-#[inline]
-pub fn ktime_ms_delta(later: Ktime, earlier: Ktime) -> i64 {
- (later - earlier).to_ms()
-}
-
-impl core::ops::Sub for Ktime {
- type Output = Ktime;
+impl core::ops::Sub for Instant {
+ type Output = Delta;
+ // never overflows
#[inline]
- fn sub(self, other: Ktime) -> Ktime {
- Self {
- inner: self.inner - other.inner,
+ fn sub(self, other: Instant) -> Delta {
+ Delta {
+ nanos: self.inner - other.inner,
}
}
}
--
2.43.0
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