Messages in this thread | ![/](/images/icornerl.gif) | | From | Andy Shevchenko <> | Date | Wed, 22 Dec 2021 20:56:12 +0200 | Subject | Re: [PATCH v11 09/15] iio: afe: rescale: reduce risk of integer overflow |
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On Wed, Dec 22, 2021 at 8:38 PM Liam Beguin <liambeguin@gmail.com> wrote: > On Wed, Dec 22, 2021 at 02:29:04PM +0200, Andy Shevchenko wrote: > > On Wed, Dec 22, 2021 at 5:47 AM Liam Beguin <liambeguin@gmail.com> wrote:
...
> > > - tmp = 1 << *val2; > > > > At some point this should be BIT()
Forgot to add, If it's 64-bit, then BIT_ULL().
> I'm not against changing this, but (to me at least) 1 << *val2 seems > more explicit as we're not working with bitfields. No?
You may add a comment. You may use int_pow(), but it will be suboptimal.
> > Rule of thumb (in accordance with C standard), always use unsigned > > value as left operand of the _left_ shift. > > Right, that makes sense! In practice though, since we'll most likely > never use higher bits of *val2 with IIO_VAL_FRACTIONAL_LOG2, would it be > enough to simply typecast? > > tmp = 1 << (unsigned int)*val2;
No, it's about the _left_ operand. I haven't checked if tmp is 64-bit, then even that would be still wrong.
-- With Best Regards, Andy Shevchenko
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