80 lines
2.5 KiB
C
80 lines
2.5 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
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#ifndef _LINUX_HELPER_MACROS_H_
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#define _LINUX_HELPER_MACROS_H_
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#include <linux/math.h>
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/**
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* find_closest - locate the closest element in a sorted array
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* @x: The reference value.
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* @a: The array in which to look for the closest element. Must be sorted
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* in ascending order.
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* @as: Size of 'a'.
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*
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* Returns the index of the element closest to 'x'.
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* Note: If using an array of negative numbers (or mixed positive numbers),
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* then be sure that 'x' is of a signed-type to get good results.
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*/
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#define find_closest(x, a, as) \
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({ \
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typeof(as) __fc_i, __fc_as = (as) - 1; \
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long __fc_mid_x, __fc_x = (x); \
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long __fc_left, __fc_right; \
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typeof(*a) const *__fc_a = (a); \
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for (__fc_i = 0; __fc_i < __fc_as; __fc_i++) { \
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__fc_mid_x = (__fc_a[__fc_i] + __fc_a[__fc_i + 1]) / 2; \
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if (__fc_x <= __fc_mid_x) { \
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__fc_left = __fc_x - __fc_a[__fc_i]; \
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__fc_right = __fc_a[__fc_i + 1] - __fc_x; \
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if (__fc_right < __fc_left) \
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__fc_i++; \
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break; \
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} \
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} \
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(__fc_i); \
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})
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/**
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* find_closest_descending - locate the closest element in a sorted array
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* @x: The reference value.
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* @a: The array in which to look for the closest element. Must be sorted
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* in descending order.
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* @as: Size of 'a'.
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*
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* Similar to find_closest() but 'a' is expected to be sorted in descending
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* order. The iteration is done in reverse order, so that the comparison
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* of '__fc_right' & '__fc_left' also works for unsigned numbers.
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*/
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#define find_closest_descending(x, a, as) \
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({ \
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typeof(as) __fc_i, __fc_as = (as) - 1; \
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long __fc_mid_x, __fc_x = (x); \
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long __fc_left, __fc_right; \
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typeof(*a) const *__fc_a = (a); \
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for (__fc_i = __fc_as; __fc_i >= 1; __fc_i--) { \
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__fc_mid_x = (__fc_a[__fc_i] + __fc_a[__fc_i - 1]) / 2; \
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if (__fc_x <= __fc_mid_x) { \
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__fc_left = __fc_x - __fc_a[__fc_i]; \
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__fc_right = __fc_a[__fc_i - 1] - __fc_x; \
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if (__fc_right < __fc_left) \
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__fc_i--; \
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break; \
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} \
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} \
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(__fc_i); \
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})
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/**
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* is_insidevar - check if the @ptr points inside the @var memory range.
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* @ptr: the pointer to a memory address.
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* @var: the variable which address and size identify the memory range.
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*
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* Evaluates to true if the address in @ptr lies within the memory
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* range allocated to @var.
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*/
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#define is_insidevar(ptr, var) \
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((uintptr_t)(ptr) >= (uintptr_t)(var) && \
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(uintptr_t)(ptr) < (uintptr_t)(var) + sizeof(var))
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#endif
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