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| -rw-r--r-- | rust/kernel/time.rs | 26 |
1 files changed, 26 insertions, 0 deletions
diff --git a/rust/kernel/time.rs b/rust/kernel/time.rs index 53b77abcb317..6c0a5e8090d0 100644 --- a/rust/kernel/time.rs +++ b/rust/kernel/time.rs @@ -528,6 +528,32 @@ impl Delta { } } + /// Return the smallest number of milliseconds greater than or equal + /// to the value in the [`Delta`]. + #[inline] + pub fn as_millis_ceil(self) -> i64 { + // Only positive values need to be rounded up: truncating division already + // rounds towards zero, i.e. up, for negative values. + // + // The usual `(nanos + d - 1) / d` is not used because the addition overflows + // once `nanos` exceeds `i64::MAX - (d - 1)`; saturating the addition instead + // would drop the rounding bias and return a result one unit too small. + let n = self.as_nanos(); + + let (n, add) = if n > 0 { (n - 1, 1) } else { (n, 0) }; + + #[cfg(CONFIG_64BIT)] + { + n / NSEC_PER_MSEC + add + } + + #[cfg(not(CONFIG_64BIT))] + // SAFETY: It is always safe to call `ktime_to_ms()` with any value. + unsafe { + bindings::ktime_to_ms(n) + add + } + } + /// Return `self % dividend` where `dividend` is in nanoseconds. /// /// The kernel doesn't have any emulation for `s64 % s64` on 32 bit platforms, so this is |