linux-kernel - Re: [PATCH v4 07/13] minmax: Introduce {min,max}

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Message-ID: <CAHp75Vf2aR1x-Nf2+uUySyGH-p12YbP2Z=Ezbspqg==pCpRbOg@mail.gmail.com>
Date:   Thu, 15 Jun 2023 16:51:32 +0300
From:   Andy Shevchenko <andy.shevchenko@...il.com>
To:     Herve Codina <herve.codina@...tlin.com>
Cc:     Liam Girdwood <lgirdwood@...il.com>,
        Mark Brown <broonie@...nel.org>,
        Rob Herring <robh+dt@...nel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        Conor Dooley <conor+dt@...nel.org>,
        Jonathan Cameron <jic23@...nel.org>,
        Lars-Peter Clausen <lars@...afoo.de>,
        Jaroslav Kysela <perex@...ex.cz>,
        Takashi Iwai <tiwai@...e.com>,
        Kuninori Morimoto <kuninori.morimoto.gx@...esas.com>,
        alsa-devel@...a-project.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-iio@...r.kernel.org,
        Christophe Leroy <christophe.leroy@...roup.eu>,
        Thomas Petazzoni <thomas.petazzoni@...tlin.com>
Subject: Re: [PATCH v4 07/13] minmax: Introduce {min,max}_array()

On Thu, Jun 15, 2023 at 12:35 PM Herve Codina <herve.codina@...tlin.com> wrote:
> On Thu, 15 Jun 2023 01:05:40 +0300
> Andy Shevchenko <andy.shevchenko@...il.com> wrote:

...

> Did the job using _Generic().

Cool! Keep my tag for that version and thank you for pursuing the
implementation that works for everybody.

> This lead to:
> --- 8< ---
> /*
>  * Remove a const qualifier

...from integer types

>  * _Generic(foo, type-name: association, ..., default: association) performs a
>  * comparison against the foo type (not the qualified type).
>  * Do not use the const keyword in the type-name as it will not match the
>  * unqualified type of foo.
>  */
> #define __unconst_type_cases(type)              \

__unconst_integer_type_cases() ?

>         unsigned type:  (unsigned type)0,       \
>         signed type:    (signed type)0
>
>

Single blank line is enough.

> #define __unconst_typeof(x) typeof(                     \

__unconst_integer_typeof() ?

>         _Generic((x),                                   \
>                 char: (char)0,                          \
>                 __unconst_type_cases(char),             \
>                 __unconst_type_cases(short),            \
>                 __unconst_type_cases(int),              \
>                 __unconst_type_cases(long),             \
>                 __unconst_type_cases(long long),        \
>                 default: (x)))
>
> /*
>  * Do not check the array parameter using __must_be_array().
>  * In the following legit use-case where the "array" passed is a simple pointer,
>  * __must_be_array() will return a failure.
>  * --- 8< ---
>  * int *buff
>  * ...
>  * min = min_array(buff, nb_items);
>  * --- 8< ---
>  *
>  * The first typeof(&(array)[0]) is needed in order to support arrays of both
>  * 'int *buff' and 'int buf[N]' types.
>  *
>  * The array can be an array of const items.
>  * typeof() keeps the const qualifier. Use __unconst_typeof() in order to
>  * discard the const qualifier for the __element variable.
>  */
> #define __minmax_array(op, array, len) ({                               \
>         typeof(&(array)[0]) __array = (array);                          \
>         typeof(len) __len = (len);                                      \
>         __unconst_typeof(__array[0]) __element = __array[--__len];      \
>         while (__len--)                                                 \
>                 __element = op(__element, __array[__len]);              \
>         __element; })
>
> /**
>  * min_array - return minimum of values present in an array
>  * @array: array
>  * @len: array length
>  *
>  * Note that @len must not be zero (empty array).
>  */
> #define min_array(array, len) __minmax_array(min, array, len)
>
> /**
>  * max_array - return maximum of values present in an array
>  * @array: array
>  * @len: array length
>  *
>  * Note that @len must not be zero (empty array).
>  */
> #define max_array(array, len) __minmax_array(max, array, len)
> --- 8< ---
>
> Do you think it looks good ?

Yes!

> For, the KUnit tests, I agree, it would be nice to have something.
> I need some more substantial work to implement and run the test in KUnit
> and the first task will be learning the KUnit test system.
> I will do that but out of this series.

Thank you, it's fine with me.

-- 
With Best Regards,
Andy Shevchenko