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