linux-kernel - Re: [PATCH v5 05/23] rust: num: add the `fls` operation

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Message-Id: <DAN1SGG5DPVE.UUW0B523LQHO@nvidia.com>
Date: Sun, 15 Jun 2025 19:51:04 +0900
From: "Alexandre Courbot" <acourbot@...dia.com>
To: "Miguel Ojeda" <miguel.ojeda.sandonis@...il.com>
Cc: "Miguel Ojeda" <ojeda@...nel.org>, "Alex Gaynor"
 <alex.gaynor@...il.com>, "Boqun Feng" <boqun.feng@...il.com>, "Gary Guo"
 <gary@...yguo.net>, Björn Roy Baron
 <bjorn3_gh@...tonmail.com>, "Andreas Hindborg" <a.hindborg@...nel.org>,
 "Alice Ryhl" <aliceryhl@...gle.com>, "Trevor Gross" <tmgross@...ch.edu>,
 "Danilo Krummrich" <dakr@...nel.org>, "David Airlie" <airlied@...il.com>,
 "Simona Vetter" <simona@...ll.ch>, "Maarten Lankhorst"
 <maarten.lankhorst@...ux.intel.com>, "Maxime Ripard" <mripard@...nel.org>,
 "Thomas Zimmermann" <tzimmermann@...e.de>, "Benno Lossin"
 <lossin@...nel.org>, "John Hubbard" <jhubbard@...dia.com>, "Ben Skeggs"
 <bskeggs@...dia.com>, "Joel Fernandes" <joelagnelf@...dia.com>, "Timur
 Tabi" <ttabi@...dia.com>, "Alistair Popple" <apopple@...dia.com>,
 <linux-kernel@...r.kernel.org>, <rust-for-linux@...r.kernel.org>,
 <nouveau@...ts.freedesktop.org>, <dri-devel@...ts.freedesktop.org>
Subject: Re: [PATCH v5 05/23] rust: num: add the `fls` operation

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@...dia.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.