/* SPDX-License-Identifier: GPL-2.0 */ #ifndef _LINUX_MATH_H #define _LINUX_MATH_H #include <linux/types.h> #include <asm/div64.h> #include <uapi/linux/kernel.h> /* * This looks more complex than it should be. But we need to * get the type for the ~ right in round_down (it needs to be * as wide as the result!), and we want to evaluate the macro * arguments just once each. */ #define __round_mask(x, y) … /** * round_up - round up to next specified power of 2 * @x: the value to round * @y: multiple to round up to (must be a power of 2) * * Rounds @x up to next multiple of @y (which must be a power of 2). * To perform arbitrary rounding up, use roundup() below. */ #define round_up(x, y) … /** * round_down - round down to next specified power of 2 * @x: the value to round * @y: multiple to round down to (must be a power of 2) * * Rounds @x down to next multiple of @y (which must be a power of 2). * To perform arbitrary rounding down, use rounddown() below. */ #define round_down(x, y) … #define DIV_ROUND_UP … #define DIV_ROUND_DOWN_ULL(ll, d) … #define DIV_ROUND_UP_ULL(ll, d) … #if BITS_PER_LONG == 32 #define DIV_ROUND_UP_SECTOR_T … #else #define DIV_ROUND_UP_SECTOR_T(ll,d) … #endif /** * roundup - round up to the next specified multiple * @x: the value to up * @y: multiple to round up to * * Rounds @x up to next multiple of @y. If @y will always be a power * of 2, consider using the faster round_up(). */ #define roundup(x, y) … /** * rounddown - round down to next specified multiple * @x: the value to round * @y: multiple to round down to * * Rounds @x down to next multiple of @y. If @y will always be a power * of 2, consider using the faster round_down(). */ #define rounddown(x, y) … /* * Divide positive or negative dividend by positive or negative divisor * and round to closest integer. Result is undefined for negative * divisors if the dividend variable type is unsigned and for negative * dividends if the divisor variable type is unsigned. */ #define DIV_ROUND_CLOSEST(x, divisor) … /* * Same as above but for u64 dividends. divisor must be a 32-bit * number. */ #define DIV_ROUND_CLOSEST_ULL(x, divisor) … #define __STRUCT_FRACT … __STRUCT_FRACT( … } __STRUCT_FRACT( … } __STRUCT_FRACT( … } __STRUCT_FRACT( … } __STRUCT_FRACT( … } __STRUCT_FRACT( … } #undef __STRUCT_FRACT /* Calculate "x * n / d" without unnecessary overflow or loss of precision. */ #define mult_frac(x, n, d) … #define sector_div(a, b) … /** * 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. * * Return: an absolute value of x. */ #define abs(x) … #define __abs_choose_expr(x, type, other) … /** * abs_diff - return absolute value of the difference between the arguments * @a: the first argument * @b: the second argument * * @a and @b have to be of the same type. With this restriction we compare * signed to signed and unsigned to unsigned. The result is the subtraction * the smaller of the two from the bigger, hence result is always a positive * value. * * Return: an absolute value of the difference between the @a and @b. */ #define abs_diff(a, b) … /** * reciprocal_scale - "scale" a value into range [0, ep_ro) * @val: value * @ep_ro: right open interval endpoint * * Perform a "reciprocal multiplication" in order to "scale" a value into * range [0, @ep_ro), where the upper interval endpoint is right-open. * This is useful, e.g. for accessing a index of an array containing * @ep_ro elements, for example. Think of it as sort of modulus, only that * the result isn't that of modulo. ;) Note that if initial input is a * small value, then result will return 0. * * Return: a result based on @val in interval [0, @ep_ro). */ static inline u32 reciprocal_scale(u32 val, u32 ep_ro) { … } u64 int_pow(u64 base, unsigned int exp); unsigned long int_sqrt(unsigned long); #if BITS_PER_LONG < 64 u32 int_sqrt64(u64 x); #else static inline u32 int_sqrt64(u64 x) { … } #endif #endif /* _LINUX_MATH_H */
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