include/linux/util_macros.h

   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