util_macros.h File Reference

#include <linux/compiler_attributes.h>
#include <linux/math.h>
#include <linux/typecheck.h>
#include <linux/stddef.h>

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Macros
#define	for_each_if(condition)   if (!(condition)) {} else
#define	find_closest(x, a, as)
#define	find_closest_descending(x, a, as)

Macro Definition Documentation

find_closest

#define find_closest	(		x,
			a,
			as
	)

Value:

({                                  \
    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 - locate the closest element in a sorted array @x: The reference value. : 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.

find_closest_descending

#define find_closest_descending	(		x,
			a,
			as
	)

Value:

({                                  \
    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);                           \
})

find_closest_descending - locate the closest element in a sorted array @x: The reference value. : 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.

for_each_if

#define for_each_if

(

condition

)

if (!(condition)) {} else

for_each_if - helper for handling conditionals in various for_each macros @condition: The condition to check

Typical use::

define for_each_foo_bar(x, y) \' list_for_each_entry(x, y->list, head) \' for_each_if(x->something == SOMETHING)

The for_each_if() macro makes the use of for_each_foo_bar() less error prone.