linux-kernel - Re: [v2 01/10] utils_macro: introduce find_closest

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Message-ID: <CAN8YU5OAdrivQuLAaQ8FyGbmGSR_Heb2Vz44PHgeQ=rrYuQBLQ@mail.gmail.com>
Date:   Mon, 8 Nov 2021 12:05:33 +0100
From:   Andrea Merello <andrea.merello@...il.com>
To:     Andy Shevchenko <andy.shevchenko@...il.com>
Cc:     Jonathan Cameron <jic23@...nel.org>,
        Mauro Carvalho Chehab <mchehab+huawei@...nel.org>,
        linux-iio <linux-iio@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        devicetree <devicetree@...r.kernel.org>,
        Lars-Peter Clausen <lars@...afoo.de>,
        Rob Herring <robh+dt@...nel.org>,
        Matt Ranostay <matt.ranostay@...sulko.com>,
        Alexandru Ardelean <ardeleanalex@...il.com>,
        jmondi <jacopo@...ndi.org>,
        Andrea Merello <andrea.merello@....it>
Subject: Re: [v2 01/10] utils_macro: introduce find_closest_unsorted()

Il giorno gio 28 ott 2021 alle ore 12:26 Andy Shevchenko
<andy.shevchenko@...il.com> ha scritto:
>
> On Thu, Oct 28, 2021 at 1:18 PM Andrea Merello <andrea.merello@...il.com> wrote:
> >
> > This is similar to find_closest() and find_closest_descending(), but, it
> > doesn't make any assumption about the array being ordered.
>
> Macros in general are not so welcoming.
> Why do you do it as a macro?

Honestly, I did that just because find_closest() and
find_closest_descending() are macros (i.e. to be consistent wrt them).
I see no drawbacks in making this a regular function indeed; just, do
you have any advice about where should it live?

> ...
>
> > +#include <linux/math.h>
>
> Wondering if the current header misses other inclusions it's a direct user of.

Looking at it, it seems that also __find_closest() actually needs
math.h because it (apparently incorrectly[*]) uses
DIV_ROUND_CLOSEST()..

[*]Indeed it seems there is another issue here about find_closest():
for example it picks the 1st element while searching for "2" in an
array like this: {1,2,..} ..This needs to be reported/fixed..



> ...
>
> > +/**
> > + * find_closest_unsorted - locate the closest element in a unsorted array
>
> an
>
> > + * @x: The reference value.
> > + * @a: The array in which to look for the closest element.
> > + * @as: Size of 'a'.
> > + *
> > + * Similar to find_closest() but 'a' has no requirement to being sorted
> > + */
>
> --
> With Best Regards,
> Andy Shevchenko