diff options
Diffstat (limited to 'include/linux/util_macros.h')
| -rw-r--r-- | include/linux/util_macros.h | 56 |
1 files changed, 40 insertions, 16 deletions
diff --git a/include/linux/util_macros.h b/include/linux/util_macros.h index 6bb460c3e818..825487fb66fa 100644 --- a/include/linux/util_macros.h +++ b/include/linux/util_macros.h @@ -4,19 +4,6 @@ #include <linux/math.h> -#define __find_closest(x, a, as, op) \ -({ \ - typeof(as) __fc_i, __fc_as = (as) - 1; \ - typeof(x) __fc_x = (x); \ - typeof(*a) const *__fc_a = (a); \ - for (__fc_i = 0; __fc_i < __fc_as; __fc_i++) { \ - if (__fc_x op DIV_ROUND_CLOSEST(__fc_a[__fc_i] + \ - __fc_a[__fc_i + 1], 2)) \ - break; \ - } \ - (__fc_i); \ -}) - /** * find_closest - locate the closest element in a sorted array * @x: The reference value. @@ -25,8 +12,27 @@ * @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) __find_closest(x, a, as, <=) +#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 @@ -36,9 +42,27 @@ * @as: Size of 'a'. * * Similar to find_closest() but 'a' is expected to be sorted in descending - * order. + * 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) __find_closest(x, a, as, >=) +#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); \ +}) /** * is_insidevar - check if the @ptr points inside the @var memory range. |