Messages in this thread | | | Date | Tue, 10 May 2022 12:16:55 -0700 | From | Yury Norov <> | Subject | Re: [PATCH 08/22] bitops: introduce MANY_BITS() macro |
| |
Hi Max,
On Tue, May 10, 2022 at 10:57:25AM -0700, Max Filippov wrote: > Hi Yury, > > On Tue, May 10, 2022 at 8:48 AM Yury Norov <yury.norov@gmail.com> wrote: > > arch/xtensa/kernel/traps.c and include/linux/log2.h define very similar > > functions with different behaviour. XTENSA defines IS_POW2(), and > > log2.h defines is_power_of_2(). The difference is that IS_POW2() > > considers 0 as power of 2, while is_power_of_2() - does not. > > IS_POW2 is constructed this way because we know that there is at least > one non-zero bit in the value that it tests. > > > This discrepancy may confuse reader. From mathematical point of view, > > 0 is not a power of 2. > > If it would reduce the confusion we can add a check that the value is > non-zero in the IS_POW2 macro. > > I'd really like to not introduce the local macro and just use something > standard,
This patch introduces a macro MANY_BITS() in include/linux/bitops.h, which is a full analogue of IS_POW2(). Would it work for you to switch to MANY_BITS()?
> but I can't use is_power_of_2 in a preprocessor condition, can I?
I believe you can't.
Thanks, Yury
| |