1 /* SPDX-License-Identifier: GPL-2.0 */ 2 #ifndef _LINUX_MATH_H 3 #define _LINUX_MATH_H 4 5 #include <linux/types.h> 6 #include <asm/div64.h> 7 #include <uapi/linux/kernel.h> 8 9 /* 10 * This looks more complex than it should be. But we need to 11 * get the type for the ~ right in round_down (it needs to be 12 * as wide as the result!), and we want to evaluate the macro 13 * arguments just once each. 14 */ 15 #define __round_mask(x, y) ((__typeof__(x))((y)-1)) 16 17 /** 18 * round_up - round up to next specified power of 2 19 * @x: the value to round 20 * @y: multiple to round up to (must be a power of 2) 21 * 22 * Rounds @x up to next multiple of @y (which must be a power of 2). 23 * To perform arbitrary rounding up, use roundup() below. 24 */ 25 #define round_up(x, y) ((((x)-1) | __round_mask(x, y))+1) 26 27 /** 28 * round_down - round down to next specified power of 2 29 * @x: the value to round 30 * @y: multiple to round down to (must be a power of 2) 31 * 32 * Rounds @x down to next multiple of @y (which must be a power of 2). 33 * To perform arbitrary rounding down, use rounddown() below. 34 */ 35 #define round_down(x, y) ((x) & ~__round_mask(x, y)) 36 37 #define DIV_ROUND_UP __KERNEL_DIV_ROUND_UP 38 39 #define DIV_ROUND_DOWN_ULL(ll, d) \ 40 ({ unsigned long long _tmp = (ll); do_div(_tmp, d); _tmp; }) 41 42 #define DIV_ROUND_UP_ULL(ll, d) \ 43 DIV_ROUND_DOWN_ULL((unsigned long long)(ll) + (d) - 1, (d)) 44 45 #if BITS_PER_LONG == 32 46 # define DIV_ROUND_UP_SECTOR_T(ll,d) DIV_ROUND_UP_ULL(ll, d) 47 #else 48 # define DIV_ROUND_UP_SECTOR_T(ll,d) DIV_ROUND_UP(ll,d) 49 #endif 50 51 /** 52 * roundup - round up to the next specified multiple 53 * @x: the value to up 54 * @y: multiple to round up to 55 * 56 * Rounds @x up to next multiple of @y. If @y will always be a power 57 * of 2, consider using the faster round_up(). 58 */ 59 #define roundup(x, y) ( \ 60 { \ 61 typeof(y) __y = y; \ 62 (((x) + (__y - 1)) / __y) * __y; \ 63 } \ 64 ) 65 /** 66 * rounddown - round down to next specified multiple 67 * @x: the value to round 68 * @y: multiple to round down to 69 * 70 * Rounds @x down to next multiple of @y. If @y will always be a power 71 * of 2, consider using the faster round_down(). 72 */ 73 #define rounddown(x, y) ( \ 74 { \ 75 typeof(x) __x = (x); \ 76 __x - (__x % (y)); \ 77 } \ 78 ) 79 80 /* 81 * Divide positive or negative dividend by positive or negative divisor 82 * and round to closest integer. Result is undefined for negative 83 * divisors if the dividend variable type is unsigned and for negative 84 * dividends if the divisor variable type is unsigned. 85 */ 86 #define DIV_ROUND_CLOSEST(x, divisor)( \ 87 { \ 88 typeof(x) __x = x; \ 89 typeof(divisor) __d = divisor; \ 90 (((typeof(x))-1) > 0 || \ 91 ((typeof(divisor))-1) > 0 || \ 92 (((__x) > 0) == ((__d) > 0))) ? \ 93 (((__x) + ((__d) / 2)) / (__d)) : \ 94 (((__x) - ((__d) / 2)) / (__d)); \ 95 } \ 96 ) 97 /* 98 * Same as above but for u64 dividends. divisor must be a 32-bit 99 * number. 100 */ 101 #define DIV_ROUND_CLOSEST_ULL(x, divisor)( \ 102 { \ 103 typeof(divisor) __d = divisor; \ 104 unsigned long long _tmp = (x) + (__d) / 2; \ 105 do_div(_tmp, __d); \ 106 _tmp; \ 107 } \ 108 ) 109 110 #define __STRUCT_FRACT(type) \ 111 struct type##_fract { \ 112 __##type numerator; \ 113 __##type denominator; \ 114 }; 115 __STRUCT_FRACT(s8) __STRUCT_FRACT(u8)116 __STRUCT_FRACT(u8) 117 __STRUCT_FRACT(s16) 118 __STRUCT_FRACT(u16) 119 __STRUCT_FRACT(s32) 120 __STRUCT_FRACT(u32) 121 #undef __STRUCT_FRACT 122 123 /* Calculate "x * n / d" without unnecessary overflow or loss of precision. */ 124 #define mult_frac(x, n, d) \ 125 ({ \ 126 typeof(x) x_ = (x); \ 127 typeof(n) n_ = (n); \ 128 typeof(d) d_ = (d); \ 129 \ 130 typeof(x_) q = x_ / d_; \ 131 typeof(x_) r = x_ % d_; \ 132 q * n_ + r * n_ / d_; \ 133 }) 134 135 #define sector_div(a, b) do_div(a, b) 136 137 /** 138 * abs - return absolute value of an argument 139 * @x: the value. If it is unsigned type, it is converted to signed type first. 140 * char is treated as if it was signed (regardless of whether it really is) 141 * but the macro's return type is preserved as char. 142 * 143 * Return: an absolute value of x. 144 */ 145 #define abs(x) __abs_choose_expr(x, long long, \ 146 __abs_choose_expr(x, long, \ 147 __abs_choose_expr(x, int, \ 148 __abs_choose_expr(x, short, \ 149 __abs_choose_expr(x, char, \ 150 __builtin_choose_expr( \ 151 __builtin_types_compatible_p(typeof(x), char), \ 152 (char)({ signed char __x = (x); __x<0?-__x:__x; }), \ 153 ((void)0))))))) 154 155 #define __abs_choose_expr(x, type, other) __builtin_choose_expr( \ 156 __builtin_types_compatible_p(typeof(x), signed type) || \ 157 __builtin_types_compatible_p(typeof(x), unsigned type), \ 158 ({ signed type __x = (x); __x < 0 ? -__x : __x; }), other) 159 160 /** 161 * abs_diff - return absolute value of the difference between the arguments 162 * @a: the first argument 163 * @b: the second argument 164 * 165 * @a and @b have to be of the same type. With this restriction we compare 166 * signed to signed and unsigned to unsigned. The result is the subtraction 167 * the smaller of the two from the bigger, hence result is always a positive 168 * value. 169 * 170 * Return: an absolute value of the difference between the @a and @b. 171 */ 172 #define abs_diff(a, b) ({ \ 173 typeof(a) __a = (a); \ 174 typeof(b) __b = (b); \ 175 (void)(&__a == &__b); \ 176 __a > __b ? (__a - __b) : (__b - __a); \ 177 }) 178 179 /** 180 * reciprocal_scale - "scale" a value into range [0, ep_ro) 181 * @val: value 182 * @ep_ro: right open interval endpoint 183 * 184 * Perform a "reciprocal multiplication" in order to "scale" a value into 185 * range [0, @ep_ro), where the upper interval endpoint is right-open. 186 * This is useful, e.g. for accessing a index of an array containing 187 * @ep_ro elements, for example. Think of it as sort of modulus, only that 188 * the result isn't that of modulo. ;) Note that if initial input is a 189 * small value, then result will return 0. 190 * 191 * Return: a result based on @val in interval [0, @ep_ro). 192 */ 193 static inline u32 reciprocal_scale(u32 val, u32 ep_ro) 194 { 195 return (u32)(((u64) val * ep_ro) >> 32); 196 } 197 198 u64 int_pow(u64 base, unsigned int exp); 199 unsigned long int_sqrt(unsigned long); 200 201 #if BITS_PER_LONG < 64 202 u32 int_sqrt64(u64 x); 203 #else int_sqrt64(u64 x)204 static inline u32 int_sqrt64(u64 x) 205 { 206 return (u32)int_sqrt(x); 207 } 208 #endif 209 210 #endif /* _LINUX_MATH_H */ 211