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