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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/**
8 * for_each_if - helper for handling conditionals in various for_each macros
9 * @condition: The condition to check
10 *
11 * Typical use::
12 *
13 * #define for_each_foo_bar(x, y) \'
14 * list_for_each_entry(x, y->list, head) \'
15 * for_each_if(x->something == SOMETHING)
16 *
17 * The for_each_if() macro makes the use of for_each_foo_bar() less error
18 * prone.
19 */
20#define for_each_if(condition) if (!(condition)) {} else
21
22/**
23 * find_closest - locate the closest element in a sorted array
24 * @x: The reference value.
25 * @a: The array in which to look for the closest element. Must be sorted
26 * in ascending order.
27 * @as: Size of 'a'.
28 *
29 * Returns the index of the element closest to 'x'.
30 * Note: If using an array of negative numbers (or mixed positive numbers),
31 * then be sure that 'x' is of a signed-type to get good results.
32 */
33#define find_closest(x, a, as) \
34({ \
35 typeof(as) __fc_i, __fc_as = (as) - 1; \
36 long __fc_mid_x, __fc_x = (x); \
37 long __fc_left, __fc_right; \
38 typeof(*a) const *__fc_a = (a); \
39 for (__fc_i = 0; __fc_i < __fc_as; __fc_i++) { \
40 __fc_mid_x = (__fc_a[__fc_i] + __fc_a[__fc_i + 1]) / 2; \
41 if (__fc_x <= __fc_mid_x) { \
42 __fc_left = __fc_x - __fc_a[__fc_i]; \
43 __fc_right = __fc_a[__fc_i + 1] - __fc_x; \
44 if (__fc_right < __fc_left) \
45 __fc_i++; \
46 break; \
47 } \
48 } \
49 (__fc_i); \
50})
51
52/**
53 * find_closest_descending - locate the closest element in a sorted array
54 * @x: The reference value.
55 * @a: The array in which to look for the closest element. Must be sorted
56 * in descending order.
57 * @as: Size of 'a'.
58 *
59 * Similar to find_closest() but 'a' is expected to be sorted in descending
60 * order. The iteration is done in reverse order, so that the comparison
61 * of '__fc_right' & '__fc_left' also works for unsigned numbers.
62 */
63#define find_closest_descending(x, a, as) \
64({ \
65 typeof(as) __fc_i, __fc_as = (as) - 1; \
66 long __fc_mid_x, __fc_x = (x); \
67 long __fc_left, __fc_right; \
68 typeof(*a) const *__fc_a = (a); \
69 for (__fc_i = __fc_as; __fc_i >= 1; __fc_i--) { \
70 __fc_mid_x = (__fc_a[__fc_i] + __fc_a[__fc_i - 1]) / 2; \
71 if (__fc_x <= __fc_mid_x) { \
72 __fc_left = __fc_x - __fc_a[__fc_i]; \
73 __fc_right = __fc_a[__fc_i - 1] - __fc_x; \
74 if (__fc_right < __fc_left) \
75 __fc_i--; \
76 break; \
77 } \
78 } \
79 (__fc_i); \
80})
81
82/**
83 * is_insidevar - check if the @ptr points inside the @var memory range.
84 * @ptr: the pointer to a memory address.
85 * @var: the variable which address and size identify the memory range.
86 *
87 * Evaluates to true if the address in @ptr lies within the memory
88 * range allocated to @var.
89 */
90#define is_insidevar(ptr, var) \
91 ((uintptr_t)(ptr) >= (uintptr_t)(var) && \
92 (uintptr_t)(ptr) < (uintptr_t)(var) + sizeof(var))
93
94#endif