Re: [PATCH 2/3] linux/bits.h: Add fixed-width GENMASK and BIT macros

Andy Shevchenko
2023-05-12T11:14:30Z

On Mon, May 08, 2023 at 10:14:02PM -0700, Lucas De Marchi wrote:
> Add GENMASK_U32(), GENMASK_U16() and GENMASK_U8() macros to create
> masks for fixed-width types and also the corresponding BIT_U32(),
> BIT_U16() and BIT_U8().

Why?

> All of those depend on a new "U" suffix added to the integer constant.
> Due to naming clashes it's better to call the macro U32. Since C doesn't
> have a proper suffix for short and char types, the U16 and U18 variants
> just use U32 with one additional check in the BIT_* macros to make
> sure the compiler gives an error when the those types overflow.
> The BIT_U16() and BIT_U8() need the help of GENMASK_INPUT_CHECK(),
> as otherwise they would allow an invalid bit to be passed. Hence
> implement them in include/linux/bits.h rather than together with
> the other BIT* variants.

So, we have _Generic() in case you still wish to implement this.

--
With Best Regards,
Andy Shevchenko