[PATCH v5 05/23] rust: num: add the `fls` operation

[Alexandre Courbot]

On Sun Jun 15, 2025 at 7:51 PM JST, Alexandre Courbot wrote:
> On Sun Jun 15, 2025 at 6:37 PM JST, Miguel Ojeda wrote:
>> On Thu, Jun 12, 2025 at 4:02 PM Alexandre Courbot <acourbot at nvidia.com> wrote:
>>>
>>> +            /// ```
>>> +            /// use kernel::num::fls_u32;
>>> +            ///
>>> +            /// assert_eq!(fls_u32(0x0), 0);
>>> +            /// assert_eq!(fls_u32(0x1), 1);
>>> +            /// assert_eq!(fls_u32(0x10), 5);
>>> +            /// assert_eq!(fls_u32(0xffff), 16);
>>> +            /// assert_eq!(fls_u32(0x8000_0000), 32);
>>> +            /// ```
>>
>> For a future patch series: this could provide examples per type
>> (passing them in the `impl_fls!` call).
>>
>> I can create a good first issue if this lands and it is not somewhere already.
>
> I was worried that the examples would be mostly duplicated, although
> it is true that seeing how the function behaves at the limits of each
> type is valuable. I'll prepare a patch to either squash for v6 or submit
> as a follow-up.

Also, although this will work nicely for `impl_fls!` which is a single
function, I'm afraid this won't scale well for `power_of_two_impl!`,
which defines 6 functions per type... Any suggestions for this case?