[PATCH] iio: Fixed IIO_VAL_FRACTIONAL calcuation for negative values

From: Anand Ashok Dumbre <anand.ashok.dumbre@xilinx.com>
To: jic23@kernel.org, knaack.h@gmx.de, lars@metafoo.de,
	pmeerw@pmeerw.net, michal.simek@xilinx.com, git@xilinx.com,
	linux-iio@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
	linux-kernel@vger.kernel.org
Cc: anandash@xilinx.com, Anand Ashok Dumbre <anand.ashok.dumbre@xilinx.com>
Subject: [PATCH] iio: Fixed IIO_VAL_FRACTIONAL calcuation for negative values
Date: Thu, 20 Aug 2020 11:09:44 -0700	[thread overview]
Message-ID: <1597946984-25844-1-git-send-email-anand.ashok.dumbre@xilinx.com> (raw)

This patch fixes IIO_VAL_FRACTIONAL calculation for negative
values where the exponent is 0.

Signed-off-by: Anand Ashok Dumbre <anand.ashok.dumbre@xilinx.com>
---
 drivers/iio/industrialio-core.c | 10 +++++++---
 1 file changed, 7 insertions(+), 3 deletions(-)

diff --git a/drivers/iio/industrialio-core.c b/drivers/iio/industrialio-core.c
index f72c2dc..cd43b17 100644
--- a/drivers/iio/industrialio-core.c
+++ b/drivers/iio/industrialio-core.c
@@ -554,6 +554,7 @@ static ssize_t __iio_format_value(char *buf, size_t len, unsigned int type,
 {
        unsigned long long tmp;
        int tmp0, tmp1;
+       s64 tmp2;
        bool scale_db = false;

        switch (type) {
@@ -576,10 +577,13 @@ static ssize_t __iio_format_value(char *buf, size_t len, unsigned int type,
                else
                        return snprintf(buf, len, "%d.%09u", vals[0], vals[1]);
        case IIO_VAL_FRACTIONAL:
-               tmp = div_s64((s64)vals[0] * 1000000000LL, vals[1]);
+               tmp2 = 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));
+               tmp0 = (int)div_s64_rem(tmp2, 1000000000, &tmp1);
+               if ((tmp2 < 0) && (tmp0 == 0))
+                       return snprintf(buf, len, "-%d.%09u", tmp0, abs(tmp1));
+               else
+                       return snprintf(buf, len, "%d.%09u", 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);
--
2.7.4

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