On Wed, 19 Jun 2019 17:07:02 +0300
Andy Shevchenko <andriy.shevchenko@xxxxxxxxxxxxxxx> wrote:
> Instead of linear approach to calculate power of 10, use generic int_pow()
> which does it better.
>
> Signed-off-by: Andy Shevchenko <andriy.shevchenko@xxxxxxxxxxxxxxx>
Hi Andy,
Looks good to me, but I would like Srinivas to take a look and
preferably test this a bit just to check we aren't all missing something
subtle!
+CC Srinivas
Thanks,
Jonathan
> ---
> .../hid-sensors/hid-sensor-attributes.c | 53 ++++++++-----------
> 1 file changed, 22 insertions(+), 31 deletions(-)
>
> diff --git a/drivers/iio/common/hid-sensors/hid-sensor-attributes.c b/drivers/iio/common/hid-sensors/hid-sensor-attributes.c
> index a8a3fe428d8d..b9dd19b34267 100644
> --- a/drivers/iio/common/hid-sensors/hid-sensor-attributes.c
> +++ b/drivers/iio/common/hid-sensors/hid-sensor-attributes.c
> @@ -8,6 +8,7 @@
> #include <linux/module.h>
> #include <linux/interrupt.h>
> #include <linux/irq.h>
> +#include <linux/kernel.h>
> #include <linux/slab.h>
> #include <linux/hid-sensor-hub.h>
> #include <linux/iio/iio.h>
> @@ -68,16 +69,6 @@ static struct {
> {HID_USAGE_SENSOR_HUMIDITY, 0, 1000, 0},
> };
>
> -static int pow_10(unsigned power)
> -{
> - int i;
> - int ret = 1;
> - for (i = 0; i < power; ++i)
> - ret = ret * 10;
> -
> - return ret;
> -}
> -
> static void simple_div(int dividend, int divisor, int *whole,
> int *micro_frac)
> {
> @@ -96,14 +87,14 @@ static void simple_div(int dividend, int divisor, int *whole,
> rem *= 10;
> exp++;
> }
> - *micro_frac = (rem / divisor) * pow_10(6-exp);
> + *micro_frac = (rem / divisor) * int_pow(10, 6 - exp);
> }
> }
>
> static void split_micro_fraction(unsigned int no, int exp, int *val1, int *val2)
> {
> - *val1 = no/pow_10(exp);
> - *val2 = no%pow_10(exp) * pow_10(6-exp);
> + *val1 = no / int_pow(10, exp);
> + *val2 = no % int_pow(10, exp) * int_pow(10, 6 - exp);
> }
>
> /*
> @@ -125,7 +116,7 @@ static void convert_from_vtf_format(u32 value, int size, int exp,
> }
> exp = hid_sensor_convert_exponent(exp);
> if (exp >= 0) {
> - *val1 = sign * value * pow_10(exp);
> + *val1 = sign * value * int_pow(10, exp);
> *val2 = 0;
> } else {
> split_micro_fraction(value, -exp, val1, val2);
> @@ -145,10 +136,10 @@ static u32 convert_to_vtf_format(int size, int exp, int val1, int val2)
> sign = -1;
> exp = hid_sensor_convert_exponent(exp);
> if (exp < 0) {
> - value = abs(val1) * pow_10(-exp);
> - value += abs(val2) / pow_10(6+exp);
> + value = abs(val1) * int_pow(10, -exp);
> + value += abs(val2) / int_pow(10, 6 + exp);
> } else
> - value = abs(val1) / pow_10(exp);
> + value = abs(val1) / int_pow(10, exp);
> if (sign < 0)
> value = ((1LL << (size * 8)) - value);
>
> @@ -211,12 +202,12 @@ int hid_sensor_write_samp_freq_value(struct hid_sensor_common *st,
> if (val1 < 0 || val2 < 0)
> return -EINVAL;
>
> - value = val1 * pow_10(6) + val2;
> + value = val1 * int_pow(10, 6) + val2;
> if (value) {
> if (st->poll.units == HID_USAGE_SENSOR_UNITS_MILLISECOND)
> - value = pow_10(9)/value;
> + value = int_pow(10, 9) / value;
> else if (st->poll.units == HID_USAGE_SENSOR_UNITS_SECOND)
> - value = pow_10(6)/value;
> + value = int_pow(10, 6) / value;
> else
> value = 0;
> }
> @@ -311,34 +302,34 @@ static void adjust_exponent_nano(int *val0, int *val1, int scale0,
> int rem;
>
> if (exp > 0) {
> - *val0 = scale0 * pow_10(exp);
> + *val0 = scale0 * int_pow(10, exp);
> res = 0;
> if (exp > 9) {
> *val1 = 0;
> return;
> }
> for (i = 0; i < exp; ++i) {
> - x = scale1 / pow_10(8 - i);
> - res += (pow_10(exp - 1 - i) * x);
> - scale1 = scale1 % pow_10(8 - i);
> + x = scale1 / int_pow(10, 8 - i);
> + res += int_pow(10, exp - 1 - i) * x;
> + scale1 = scale1 % int_pow(10, 8 - i);
> }
> *val0 += res;
> - *val1 = scale1 * pow_10(exp);
> + *val1 = scale1 * int_pow(10, exp);
> } else if (exp < 0) {
> exp = abs(exp);
> if (exp > 9) {
> *val0 = *val1 = 0;
> return;
> }
> - *val0 = scale0 / pow_10(exp);
> - rem = scale0 % pow_10(exp);
> + *val0 = scale0 / int_pow(10, exp);
> + rem = scale0 % int_pow(10, exp);
> res = 0;
> for (i = 0; i < (9 - exp); ++i) {
> - x = scale1 / pow_10(8 - i);
> - res += (pow_10(8 - exp - i) * x);
> - scale1 = scale1 % pow_10(8 - i);
> + x = scale1 / int_pow(10, 8 - i);
> + res += int_pow(10, 8 - exp - i) * x;
> + scale1 = scale1 % int_pow(10, 8 - i);
> }
> - *val1 = rem * pow_10(9 - exp) + res;
> + *val1 = rem * int_pow(10, 9 - exp) + res;
> } else {
> *val0 = scale0;
> *val1 = scale1;
