| Message ID | 20211028101840.24632-2-andrea.merello@gmail.com (mailing list archive) |
|---|---|
| State | Changes Requested |
| Headers | show |
| Series | Add support for Bosch BNO055 IMU | expand |
On Thu, Oct 28, 2021 at 1:18 PM Andrea Merello <andrea.merello@gmail.com> wrote: > > This is similar to find_closest() and find_closest_descending(), but, it > doesn't make any assumption about the array being ordered. Macros in general are not so welcoming. Why do you do it as a macro? ... > +#include <linux/math.h> Wondering if the current header misses other inclusions it's a direct user of. ... > +/** > + * find_closest_unsorted - locate the closest element in a unsorted array an > + * @x: The reference value. > + * @a: The array in which to look for the closest element. > + * @as: Size of 'a'. > + * > + * Similar to find_closest() but 'a' has no requirement to being sorted > + */
Il giorno gio 28 ott 2021 alle ore 12:26 Andy Shevchenko <andy.shevchenko@gmail.com> ha scritto: > > On Thu, Oct 28, 2021 at 1:18 PM Andrea Merello <andrea.merello@gmail.com> wrote: > > > > This is similar to find_closest() and find_closest_descending(), but, it > > doesn't make any assumption about the array being ordered. > > Macros in general are not so welcoming. > Why do you do it as a macro? Honestly, I did that just because find_closest() and find_closest_descending() are macros (i.e. to be consistent wrt them). I see no drawbacks in making this a regular function indeed; just, do you have any advice about where should it live? > ... > > > +#include <linux/math.h> > > Wondering if the current header misses other inclusions it's a direct user of. Looking at it, it seems that also __find_closest() actually needs math.h because it (apparently incorrectly[*]) uses DIV_ROUND_CLOSEST().. [*]Indeed it seems there is another issue here about find_closest(): for example it picks the 1st element while searching for "2" in an array like this: {1,2,..} ..This needs to be reported/fixed.. > ... > > > +/** > > + * find_closest_unsorted - locate the closest element in a unsorted array > > an > > > + * @x: The reference value. > > + * @a: The array in which to look for the closest element. > > + * @as: Size of 'a'. > > + * > > + * Similar to find_closest() but 'a' has no requirement to being sorted > > + */ > > -- > With Best Regards, > Andy Shevchenko
diff --git a/include/linux/util_macros.h b/include/linux/util_macros.h index 72299f261b25..b48f80ceb380 100644 --- a/include/linux/util_macros.h +++ b/include/linux/util_macros.h @@ -2,6 +2,8 @@ #ifndef _LINUX_HELPER_MACROS_H_ #define _LINUX_HELPER_MACROS_H_ +#include <linux/math.h> + #define __find_closest(x, a, as, op) \ ({ \ typeof(as) __fc_i, __fc_as = (as) - 1; \ @@ -38,4 +40,28 @@ */ #define find_closest_descending(x, a, as) __find_closest(x, a, as, >=) +/** + * find_closest_unsorted - locate the closest element in a unsorted array + * @x: The reference value. + * @a: The array in which to look for the closest element. + * @as: Size of 'a'. + * + * Similar to find_closest() but 'a' has no requirement to being sorted + */ +#define find_closest_unsorted(x, a, as) \ +({ \ + typeof(x) __fc_best_delta, __fc_delta; \ + typeof(as) __fc_i, __fc_best_idx; \ + bool __fc_first = true; \ + for (__fc_i = 0; __fc_i < (as); __fc_i++) { \ + __fc_delta = abs(a[__fc_i] - (x)); \ + if (__fc_first || __fc_delta < __fc_best_delta) { \ + __fc_best_delta = __fc_delta; \ + __fc_best_idx = __fc_i; \ + } \ + __fc_first = false; \ + } \ + (__fc_best_idx); \ +}) + #endif
This is similar to find_closest() and find_closest_descending(), but, it doesn't make any assumption about the array being ordered. Signed-off-by: Andrea Merello <andrea.merello@iit.it> --- include/linux/util_macros.h | 26 ++++++++++++++++++++++++++ 1 file changed, 26 insertions(+)