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Message-ID: <20241016035214.2229-3-fujita.tomonori@gmail.com>
Date: Wed, 16 Oct 2024 12:52:07 +0900
From: FUJITA Tomonori <fujita.tomonori@...il.com>
To: netdev@...r.kernel.org
Cc: rust-for-linux@...r.kernel.org,
andrew@...n.ch,
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linux-kernel@...r.kernel.org
Subject: [PATCH net-next v3 2/8] rust: time: Introduce Delta type
Introduce a type representing a span of time. Define our own type
because `core::time::Duration` is large and could panic during
creation.
time::Ktime could be also used for time duration but timestamp and
timedelta are different so better to use a new type.
i64 is used instead of u64 to represent a span of time; some C drivers
uses negative Deltas and i64 is more compatible with Ktime using i64
too (e.g., ktime_[us|ms]_delta() APIs return i64 so we create Delta
object without type conversion.
Delta::from_[micro|millis|secs] APIs take i64. When a span of time
overflows, i64::MAX is used.
Signed-off-by: FUJITA Tomonori <fujita.tomonori@...il.com>
---
rust/kernel/time.rs | 74 +++++++++++++++++++++++++++++++++++++++++++++
1 file changed, 74 insertions(+)
diff --git a/rust/kernel/time.rs b/rust/kernel/time.rs
index 4a7c6037c256..38a70dc98083 100644
--- a/rust/kernel/time.rs
+++ b/rust/kernel/time.rs
@@ -8,9 +8,15 @@
//! C header: [`include/linux/jiffies.h`](srctree/include/linux/jiffies.h).
//! C header: [`include/linux/ktime.h`](srctree/include/linux/ktime.h).
+/// The number of nanoseconds per microsecond.
+pub const NSEC_PER_USEC: i64 = bindings::NSEC_PER_USEC as i64;
+
/// The number of nanoseconds per millisecond.
pub const NSEC_PER_MSEC: i64 = bindings::NSEC_PER_MSEC as i64;
+/// The number of nanoseconds per second.
+pub const NSEC_PER_SEC: i64 = bindings::NSEC_PER_SEC as i64;
+
/// The time unit of Linux kernel. One jiffy equals (1/HZ) second.
pub type Jiffies = core::ffi::c_ulong;
@@ -81,3 +87,71 @@ fn sub(self, other: Ktime) -> Ktime {
}
}
}
+
+/// A span of time.
+#[derive(Copy, Clone)]
+pub struct Delta {
+ nanos: i64,
+}
+
+impl Delta {
+ /// Create a new `Delta` from a number of nanoseconds.
+ #[inline]
+ pub fn from_nanos(nanos: i64) -> Self {
+ Self { nanos }
+ }
+
+ /// Create a new `Delta` from a number of microseconds.
+ #[inline]
+ pub fn from_micros(micros: i64) -> Self {
+ Self {
+ nanos: micros.saturating_mul(NSEC_PER_USEC),
+ }
+ }
+
+ /// Create a new `Delta` from a number of milliseconds.
+ #[inline]
+ pub fn from_millis(millis: i64) -> Self {
+ Self {
+ nanos: millis.saturating_mul(NSEC_PER_MSEC),
+ }
+ }
+
+ /// Create a new `Delta` from a number of seconds.
+ #[inline]
+ pub fn from_secs(secs: i64) -> Self {
+ Self {
+ nanos: secs.saturating_mul(NSEC_PER_SEC),
+ }
+ }
+
+ /// Return `true` if the `Detla` spans no time.
+ #[inline]
+ pub fn is_zero(self) -> bool {
+ self.nanos == 0
+ }
+
+ /// Return the number of nanoseconds in the `Delta`.
+ #[inline]
+ pub fn as_nanos(self) -> i64 {
+ self.nanos
+ }
+
+ /// Return the number of microseconds in the `Delta`.
+ #[inline]
+ pub fn as_micros(self) -> i64 {
+ self.nanos / NSEC_PER_USEC
+ }
+
+ /// Return the number of milliseconds in the `Delta`.
+ #[inline]
+ pub fn as_millis(self) -> i64 {
+ self.nanos / NSEC_PER_MSEC
+ }
+
+ /// Return the number of seconds in the `Delta`.
+ #[inline]
+ pub fn as_secs(self) -> i64 {
+ self.nanos / NSEC_PER_SEC
+ }
+}
--
2.43.0
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