LXR linux/include/linux/util

   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
  42