include/linux/util_macros.h

   1 /* SPDX-License-Identifier: GPL-2.0 */
   2 #ifndef _LINUX_HELPER_MACROS_H_
   3 #define _LINUX_HELPER_MACROS_H_
   4
   5 #define __find_closest(x, a, as, op)                                    \
   6 ({                                                                      \
   7         typeof(as) __fc_i, __fc_as = (as) - 1;                          \
   8         typeof(x) __fc_x = (x);                                         \
   9         typeof(*a) const *__fc_a = (a);                                 \
  10         for (__fc_i = 0; __fc_i < __fc_as; __fc_i++) {                  \
  11                 if (__fc_x op DIV_ROUND_CLOSEST(__fc_a[__fc_i] +        \
  12                                                 __fc_a[__fc_i + 1], 2)) \
  13                         break;                                          \
  14         }                                                               \
  15         (__fc_i);                                                       \
  16 })
  17
  18 /**
  19  * find_closest - locate the closest element in a sorted array
  20  * @x: The reference value.
  21  * @a: The array in which to look for the closest element. Must be sorted
  22  *  in ascending order.
  23  * @as: Size of 'a'.
  24  *
  25  * Returns the index of the element closest to 'x'.
  26  */
  27 #define find_closest(x, a, as) __find_closest(x, a, as, <=)
  28
  29 /**
  30  * find_closest_descending - locate the closest element in a sorted array
  31  * @x: The reference value.
  32  * @a: The array in which to look for the closest element. Must be sorted
  33  *  in descending order.
  34  * @as: Size of 'a'.
  35  *
  36  * Similar to find_closest() but 'a' is expected to be sorted in descending
  37  * order.
  38  */
  39 #define find_closest_descending(x, a, as) __find_closest(x, a, as, >=)
  40
  41 #endif