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/* SPDX-License-Identifier: GPL-2.0 */
#ifndef _LINUX_HELPER_MACROS_H_
#define _LINUX_HELPER_MACROS_H_
/**
* find_closest - locate the closest element in a sorted array
* @x: The reference value.
* @a: The array in which to look for the closest element. Must be sorted
* in ascending order.
* @as: Size of 'a'.
*
* Returns the index of the element closest to 'x'.
* Note: If using an array of negative numbers (or mixed positive numbers),
* then be sure that 'x' is of a signed-type to get good results.
*/
#define find_closest(x, a, as) \
({ \
typeof(as) __fc_i, __fc_as = (as) - 1; \
long __fc_mid_x, __fc_x = (x); \
long __fc_left, __fc_right; \
typeof(*a) const *__fc_a = (a); \
for (__fc_i = 0; __fc_i < __fc_as; __fc_i++) { \
__fc_mid_x = (__fc_a[__fc_i] + __fc_a[__fc_i + 1]) / 2; \
if (__fc_x <= __fc_mid_x) { \
__fc_left = __fc_x - __fc_a[__fc_i]; \
__fc_right = __fc_a[__fc_i + 1] - __fc_x; \
if (__fc_right < __fc_left) \
__fc_i++; \
break; \
} \
} \
(__fc_i); \
})
/**
* find_closest_descending - locate the closest element in a sorted array
* @x: The reference value.
* @a: The array in which to look for the closest element. Must be sorted
* in descending order.
* @as: Size of 'a'.
*
* Similar to find_closest() but 'a' is expected to be sorted in descending
* order. The iteration is done in reverse order, so that the comparison
* of '__fc_right' & '__fc_left' also works for unsigned numbers.
*/
#define find_closest_descending(x, a, as) \
({ \
typeof(as) __fc_i, __fc_as = (as) - 1; \
long __fc_mid_x, __fc_x = (x); \
long __fc_left, __fc_right; \
typeof(*a) const *__fc_a = (a); \
for (__fc_i = __fc_as; __fc_i >= 1; __fc_i--) { \
__fc_mid_x = (__fc_a[__fc_i] + __fc_a[__fc_i - 1]) / 2; \
if (__fc_x <= __fc_mid_x) { \
__fc_left = __fc_x - __fc_a[__fc_i]; \
__fc_right = __fc_a[__fc_i - 1] - __fc_x; \
if (__fc_right < __fc_left) \
__fc_i--; \
break; \
} \
} \
(__fc_i); \
})
#endif
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