1 /* SPDX-License-Identifier: GPL-2.0 */
2 #ifndef _LINUX_HELPER_MACROS_H_
3 #define _LINUX_HELPER_MACROS_H_
4 
5 #include <linux/math.h>
6 
7 #define __find_closest(x, a, as, op)					\
8 ({									\
9 	typeof(as) __fc_i, __fc_as = (as) - 1;				\
10 	typeof(x) __fc_x = (x);						\
11 	typeof(*a) const *__fc_a = (a);					\
12 	for (__fc_i = 0; __fc_i < __fc_as; __fc_i++) {			\
13 		if (__fc_x op DIV_ROUND_CLOSEST(__fc_a[__fc_i] +	\
14 						__fc_a[__fc_i + 1], 2))	\
15 			break;						\
16 	}								\
17 	(__fc_i);							\
18 })
19 
20 /**
21  * find_closest - locate the closest element in a sorted array
22  * @x: The reference value.
23  * @a: The array in which to look for the closest element. Must be sorted
24  *  in ascending order.
25  * @as: Size of 'a'.
26  *
27  * Returns the index of the element closest to 'x'.
28  */
29 #define find_closest(x, a, as) __find_closest(x, a, as, <=)
30 
31 /**
32  * find_closest_descending - locate the closest element in a sorted array
33  * @x: The reference value.
34  * @a: The array in which to look for the closest element. Must be sorted
35  *  in descending order.
36  * @as: Size of 'a'.
37  *
38  * Similar to find_closest() but 'a' is expected to be sorted in descending
39  * order.
40  */
41 #define find_closest_descending(x, a, as) __find_closest(x, a, as, >=)
42 
43 /**
44  * is_insidevar - check if the @ptr points inside the @var memory range.
45  * @ptr:	the pointer to a memory address.
46  * @var:	the variable which address and size identify the memory range.
47  *
48  * Evaluates to true if the address in @ptr lies within the memory
49  * range allocated to @var.
50  */
51 #define is_insidevar(ptr, var)						\
52 	((uintptr_t)(ptr) >= (uintptr_t)(var) &&			\
53 	 (uintptr_t)(ptr) <  (uintptr_t)(var) + sizeof(var))
54 
55 #endif
56