LXR linux/include/linux/util

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