From: "Daniel Almeida" <daniel.almeida@collabora.com>
To: "Nicolas Dufresne" <nicolas@ndufresne.ca>
Cc: wedsonaf@gmail.com, ojeda@kernel.org, mchehab@kernel.org,
hverkuil@xs4all.nl, rust-for-linux@vger.kernel.org,
linux-kernel@vger.kernel.org, linux-media@vger.kernel.org,
kernel@collabora.com
Subject: Re: [RFC PATCH v2 2/2] media: rkvdec: rewrite parts of the driver in Rust
Date: Thu, 07 Mar 2024 21:45:33 +0000 [thread overview]
Message-ID: <144b27-65ea3580-f-61876d80@130641868> (raw)
In-Reply-To: <c70935815ffc29ae5256b94c0e4880952abad79c.camel@ndufresne.ca>
Hi Nicolas,
> struct reg123 {
> val1 :3 // bit 31-29
> val2 :20 // bit 28-9
> val3 :9 // bit 8-0
> };
What you're describing can be modeled as Ranges in Rust:
```
use core::ops::Range;
struct Foo {
reg1: Range<u32>,
reg2: Range<u32>,
reg3: Range<u32>
}
const FOO_REGMAP: Foo = Foo {
reg1: 0..3,
reg2: 3..24,
reg3: 24..32
};
```
It becomes more useful when you pair that with a bit writer. For an example of previous art, see Faith's work: [0]
This has asserts in the right places so that you do not shoot yourself in the foot. IMHO, such a data structure can be shared with the whole Rust code in the kernel.
You can then describe your writes using the ranges, e.g.: [1]
But as we've established, instead of writing the ranges down directly, you can simply refer to them as FOO_REGMAP.reg1, FOO_REGMAP.reg2 and so on.
I believe this is both more readable and safer.
[0]: https://gitlab.freedesktop.org/mesa/mesa/-/blob/main/src/nouveau/compiler/bitview/lib.rs?ref_type=heads
[1]: https://gitlab.freedesktop.org/mesa/mesa/-/blob/main/src/nouveau/compiler/nak/encode_sm70.rs?ref_type=heads#L228
next prev parent reply other threads:[~2024-03-07 21:45 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-02-27 21:51 [RFC PATCH 0/1] Rewrite the VP9 codec library in Rust Daniel Almeida
2024-02-27 21:51 ` [RFC PATCH 1/1] v4l2-core: rewrite the VP9 " Daniel Almeida
2024-02-28 14:13 ` Alice Ryhl
2024-02-28 17:59 ` Daniel Almeida
2024-03-07 19:08 ` [RFC PATCH v2 0/2] Rewrite parts of rkvdec driver and the VP9 codec " Daniel Almeida
2024-03-07 19:08 ` [RFC PATCH v2 1/2] v4l2-core: rewrite the VP9 " Daniel Almeida
2024-03-07 19:08 ` [RFC PATCH v2 2/2] media: rkvdec: rewrite parts of the driver " Daniel Almeida
2024-03-07 20:56 ` Nicolas Dufresne
2024-03-07 21:45 ` Daniel Almeida [this message]
2024-03-07 20:04 ` [RFC PATCH v2 0/2] Rewrite parts of rkvdec driver and the VP9 codec library " Deborah Brouwer
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