On 02/09/16 19:27, Gregor Boirie wrote:
> 7985e7c100 ("iio: Introduce a new fractional value type") introduced a
> new IIO_VAL_FRACTIONAL value type meant to represent rational type numbers
> expressed by a numerator and denominator combination.
>
> Formating of IIO_VAL_FRACTIONAL values relies upon do_div() usage. This
> fails handling negative values properly since parameters are reevaluated
> as unsigned values.
> Fix this by using div_s64_rem() instead. Computed integer part will carry
> properly signed value. Formatted fractional part will always be positive.
>
> Fixes: 7985e7c100 ("iio: Introduce a new fractional value type")
> Signed-off-by: Gregor Boirie <gregor.boirie@xxxxxxxxxx>
Hi Gregor,
While this looks sensible to me, I always gain an almighty headache when
I hit the various divide functions.
Lars, the fractional code was yours in the first place.
If you have time can you sanity check this please.
Jonathan
> ---
> drivers/iio/industrialio-core.c | 5 ++---
> 1 file changed, 2 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/iio/industrialio-core.c b/drivers/iio/industrialio-core.c
> index f914d5d..d2b8899 100644
> --- a/drivers/iio/industrialio-core.c
> +++ b/drivers/iio/industrialio-core.c
> @@ -613,9 +613,8 @@ ssize_t iio_format_value(char *buf, unsigned int type, int size, int *vals)
> return sprintf(buf, "%d.%09u\n", vals[0], vals[1]);
> case IIO_VAL_FRACTIONAL:
> tmp = div_s64((s64)vals[0] * 1000000000LL, vals[1]);
> - vals[1] = do_div(tmp, 1000000000LL);
> - vals[0] = tmp;
> - return sprintf(buf, "%d.%09u\n", vals[0], vals[1]);
> + vals[0] = (int)div_s64_rem(tmp, 1000000000, &vals[1]);
> + return sprintf(buf, "%d.%09u\n", vals[0], abs(vals[1]));
> case IIO_VAL_FRACTIONAL_LOG2:
> tmp = (s64)vals[0] * 1000000000LL >> vals[1];
> vals[1] = do_div(tmp, 1000000000LL);
>
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