| Message ID | 20190821155023.6333-1-alexander.stein@systec-electronic.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | [1/1] iio: core: Fix fractional format generation | expand |
On 8/21/19 5:50 PM, Alexander Stein wrote: > In case the result is -0.3252 tmp0 is 0 after the div_s64_rem, so tmp0 is > non-negative which results in an output of 0.3252. > Fix this by explicitly handling the negative sign ourselves. Hi, Thanks for you patch. Some comments inline. > > Signed-off-by: Alexander Stein <alexander.stein@systec-electronic.com> > --- > drivers/iio/industrialio-core.c | 5 +++-- > 1 file changed, 3 insertions(+), 2 deletions(-) > > diff --git a/drivers/iio/industrialio-core.c b/drivers/iio/industrialio-core.c > index 245b5844028d..18350c1959ae 100644 > --- a/drivers/iio/industrialio-core.c > +++ b/drivers/iio/industrialio-core.c > @@ -568,6 +568,7 @@ static ssize_t __iio_format_value(char *buf, size_t len, unsigned int type, > { > unsigned long long tmp; > int tmp0, tmp1; > + const char *sign = vals[0] < 0 ? "-" : ""; > bool scale_db = false; > > switch (type) { > @@ -593,11 +594,11 @@ static ssize_t __iio_format_value(char *buf, size_t len, unsigned int type, > tmp = div_s64((s64)vals[0] * 1000000000LL, vals[1]); > tmp1 = vals[1]; > tmp0 = (int)div_s64_rem(tmp, 1000000000, &tmp1); > - return snprintf(buf, len, "%d.%09u", tmp0, abs(tmp1)); > + return snprintf(buf, len, "%s%u.%09u", sign, abs(tmp0), abs(tmp1)); I think this breaks the case where vals[1] is negative, but vals[0] is positive. Maybe we can use a similar approach as for IIO_VAL_INT_PLUS_NANO. Maybe even put this into a small helper function. > case IIO_VAL_FRACTIONAL_LOG2: > tmp = shift_right((s64)vals[0] * 1000000000LL, vals[1]); > tmp0 = (int)div_s64_rem(tmp, 1000000000LL, &tmp1); > - return snprintf(buf, len, "%d.%09u", tmp0, abs(tmp1)); > + return snprintf(buf, len, "%s%u.%09u", sign, abs(tmp0), abs(tmp1)); > case IIO_VAL_INT_MULTIPLE: > { > int i; >
diff --git a/drivers/iio/industrialio-core.c b/drivers/iio/industrialio-core.c index 245b5844028d..18350c1959ae 100644 --- a/drivers/iio/industrialio-core.c +++ b/drivers/iio/industrialio-core.c @@ -568,6 +568,7 @@ static ssize_t __iio_format_value(char *buf, size_t len, unsigned int type, { unsigned long long tmp; int tmp0, tmp1; + const char *sign = vals[0] < 0 ? "-" : ""; bool scale_db = false; switch (type) { @@ -593,11 +594,11 @@ static ssize_t __iio_format_value(char *buf, size_t len, unsigned int type, tmp = div_s64((s64)vals[0] * 1000000000LL, vals[1]); tmp1 = vals[1]; tmp0 = (int)div_s64_rem(tmp, 1000000000, &tmp1); - return snprintf(buf, len, "%d.%09u", tmp0, abs(tmp1)); + return snprintf(buf, len, "%s%u.%09u", sign, abs(tmp0), abs(tmp1)); case IIO_VAL_FRACTIONAL_LOG2: tmp = shift_right((s64)vals[0] * 1000000000LL, vals[1]); tmp0 = (int)div_s64_rem(tmp, 1000000000LL, &tmp1); - return snprintf(buf, len, "%d.%09u", tmp0, abs(tmp1)); + return snprintf(buf, len, "%s%u.%09u", sign, abs(tmp0), abs(tmp1)); case IIO_VAL_INT_MULTIPLE: { int i;
In case the result is -0.3252 tmp0 is 0 after the div_s64_rem, so tmp0 is non-negative which results in an output of 0.3252. Fix this by explicitly handling the negative sign ourselves. Signed-off-by: Alexander Stein <alexander.stein@systec-electronic.com> --- drivers/iio/industrialio-core.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-)