Re: [PATCH v1] rust: time: Avoid 64-bit integer division

[FUJITA Tomonori]

On Thu, 1 May 2025 06:25:04 -0700
Boqun Feng <boqun.feng@xxxxxxxxx> wrote:

> On Thu, May 01, 2025 at 03:22:00PM +0200, Miguel Ojeda wrote:
>> On Thu, May 1, 2025 at 3:12 PM Boqun Feng <boqun.feng@xxxxxxxxx> wrote:
>> >
>> >         #[cfg(CONFIG_ARM)]
>> >         fn ns_to_ms(ns: i64) -> i64 {
>> >
>> >         #[cfg(not(CONFIG_ARM))]
>> >         fn ns_to_ms(ns: i64) -> i64 {
>> 
>> I think `cfg`s may be better inside, i.e. as local as reasonably
>> possible, so that we share e.g. signature as well as any attributes
>> and docs.
>> 
> 
> Fair enough.

I'll go with the following.

#[inline]
pub fn as_millis(self) -> i64 {
    #[cfg(CONFIG_ARM)]
    // SAFETY: It is always safe to call `ktime_to_ms()` with any value.
    unsafe {
        bindings::ktime_to_ms(self.as_nanos())
    }

    #[cfg(not(CONFIG_ARM))]
    {
        self.as_nanos() / NSEC_PER_MSEC
    }
}