Hi Andy,
On Mon, 12 Jun 2023 17:10:40 +0300
Andy Shevchenko <andy.shevchenko@xxxxxxxxx> wrote:
> On Mon, Jun 12, 2023 at 3:30 PM Herve Codina <herve.codina@xxxxxxxxxxx> wrote:
> >
> > Introduce min_array() (resp max_array()) in order to get the
> > minimal (resp maximum) of values present in an array.
>
> Some comments below, after addressing them,
> Reviewed-by: Andy Shevchenko <andy.shevchenko@xxxxxxxxx>
>
> > Signed-off-by: Herve Codina <herve.codina@xxxxxxxxxxx>
> > ---
> > include/linux/minmax.h | 26 ++++++++++++++++++++++++++
> > 1 file changed, 26 insertions(+)
> >
> > diff --git a/include/linux/minmax.h b/include/linux/minmax.h
> > index 396df1121bff..37a211f22404 100644
> > --- a/include/linux/minmax.h
> > +++ b/include/linux/minmax.h
> > @@ -133,6 +133,32 @@
> > */
> > #define max_t(type, x, y) __careful_cmp((type)(x), (type)(y), >)
> >
> > +#define __minmax_array(op, array, len) ({ \
>
> Maybe it's my MUA, maybe the code contains spaces, can you switch to
> TABs if it's the case?
>
> > + typeof(array) __array = (array); \
>
> We have __must_be_array()
Using __must_be_array() will lead to some failure.
Indeed, we can have:
--- 8< ---
int *buff
...
min = min_array(buff, nb_item);
--- 8< ---
In this case, __must_be_array() will report that buff is not an array.
To avoid any confusion, what do you think if I renamed {min,max}_array()
to {min,max}_buffer() and replace __array by __buff and use *(__buff + xxx)
instead of array[xxx] in the macro.
This will lead to:
--- 8< ---
#define __minmax_buffer(op, buff, len) ({ \
typeof(buff) __buff = (buff); \
typeof(len) __len = (len); \
typeof(*buff + 0) __element = *(__buff + --__len); \
while (__len--) \
__element = op(__element, *(__buff + __len])); \
__element; })
#define min_buffer(buffer, len) __minmax_array(min, buffer, len)
#define max_buffer(buffer, len) __minmax_array(max, buffer, len)
--- 8< ---
Regards,
Hervé
>
> You will need to fix the inclusions in minmax.h at the same time, it needs
> linux/build_bug.h (which includes compiler.h needed for __UNIQUE_ID()
> and for the above mentioned one).
>
> > + typeof(len) __len = (len); \
> > + typeof(*__array + 0) __element = __array[--__len]; \
>
> After above, this can be written as __array[0].
>
> > + 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)
> > +
> > /**
> > * clamp_t - return a value clamped to a given range using a given type
> > * @type: the type of variable to use
>
