Re: [PATCH v11 09/15] iio: afe: rescale: reduce risk of integer overflow

Andy Shevchenko
2021-12-22T12:31:06Z

On Wed, Dec 22, 2021 at 5:47 AM Liam Beguin <liambeguin@gmail.com> wrote:
>
> From: Liam Beguin <lvb@xiphos.com>
>
> Reduce the risk of integer overflow by doing the scale calculation on
> a 64-bit integer. Since the rescaling is only performed on *val, reuse
> the IIO_VAL_FRACTIONAL_LOG2 case.

...

> - tmp = 1 << *val2;

At some point this should be BIT()
Rule of thumb (in accordance with C standard), always use unsigned
value as left operand of the _left_ shift.

> + if (scale_type == IIO_VAL_FRACTIONAL)
> + tmp = *val2;
> + else
> + tmp = 1 << *val2;

--
With Best Regards,
Andy Shevchenko