diff options
Diffstat (limited to 'include/linux/math.h')
| -rw-r--r-- | include/linux/math.h | 25 |
1 files changed, 21 insertions, 4 deletions
diff --git a/include/linux/math.h b/include/linux/math.h index f5f18dc3616b..6dc1d1d32fbc 100644 --- a/include/linux/math.h +++ b/include/linux/math.h @@ -34,6 +34,18 @@ */ #define round_down(x, y) ((x) & ~__round_mask(x, y)) +/** + * DIV_ROUND_UP_POW2 - divide and round up + * @n: numerator + * @d: denominator (must be a power of 2) + * + * Divides @n by @d and rounds up to next multiple of @d (which must be a power + * of 2). Avoids integer overflows that may occur with __KERNEL_DIV_ROUND_UP(). + * Performance is roughly equivalent to __KERNEL_DIV_ROUND_UP(). + */ +#define DIV_ROUND_UP_POW2(n, d) \ + ((n) / (d) + !!((n) & ((d) - 1))) + #define DIV_ROUND_UP __KERNEL_DIV_ROUND_UP #define DIV_ROUND_DOWN_ULL(ll, d) \ @@ -136,11 +148,16 @@ __STRUCT_FRACT(u32) /** * abs - return absolute value of an argument - * @x: the value. If it is unsigned type, it is converted to signed type first. - * char is treated as if it was signed (regardless of whether it really is) - * but the macro's return type is preserved as char. + * @x: the value. + * + * If it is unsigned type, @x is converted to signed type first. + * char is treated as if it was signed (regardless of whether it really is) + * but the macro's return type is preserved as char. + * + * NOTE, for signed type if @x is the minimum, the returned result is undefined + * as there is not enough bits to represent it as a positive number. * - * Return: an absolute value of x. + * Return: an absolute value of @x. */ #define abs(x) __abs_choose_expr(x, long long, \ __abs_choose_expr(x, long, \ |