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aa6159ab AS |
1 | /* SPDX-License-Identifier: GPL-2.0 */ |
2 | #ifndef _LINUX_MATH_H | |
3 | #define _LINUX_MATH_H | |
4 | ||
e820a337 | 5 | #include <linux/types.h> |
aa6159ab AS |
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 | ||
e820a337 AS |
110 | #define __STRUCT_FRACT(type) \ |
111 | struct type##_fract { \ | |
112 | __##type numerator; \ | |
113 | __##type denominator; \ | |
114 | }; | |
115 | __STRUCT_FRACT(s16) | |
116 | __STRUCT_FRACT(u16) | |
117 | __STRUCT_FRACT(s32) | |
118 | __STRUCT_FRACT(u32) | |
119 | #undef __STRUCT_FRACT | |
120 | ||
048a9883 AD |
121 | /* Calculate "x * n / d" without unnecessary overflow or loss of precision. */ |
122 | #define mult_frac(x, n, d) \ | |
123 | ({ \ | |
124 | typeof(x) x_ = (x); \ | |
125 | typeof(n) n_ = (n); \ | |
126 | typeof(d) d_ = (d); \ | |
127 | \ | |
128 | typeof(x_) q = x_ / d_; \ | |
129 | typeof(x_) r = x_ % d_; \ | |
130 | q * n_ + r * n_ / d_; \ | |
131 | }) | |
aa6159ab AS |
132 | |
133 | #define sector_div(a, b) do_div(a, b) | |
134 | ||
135 | /** | |
136 | * abs - return absolute value of an argument | |
137 | * @x: the value. If it is unsigned type, it is converted to signed type first. | |
138 | * char is treated as if it was signed (regardless of whether it really is) | |
139 | * but the macro's return type is preserved as char. | |
140 | * | |
141 | * Return: an absolute value of x. | |
142 | */ | |
143 | #define abs(x) __abs_choose_expr(x, long long, \ | |
144 | __abs_choose_expr(x, long, \ | |
145 | __abs_choose_expr(x, int, \ | |
146 | __abs_choose_expr(x, short, \ | |
147 | __abs_choose_expr(x, char, \ | |
148 | __builtin_choose_expr( \ | |
149 | __builtin_types_compatible_p(typeof(x), char), \ | |
150 | (char)({ signed char __x = (x); __x<0?-__x:__x; }), \ | |
151 | ((void)0))))))) | |
152 | ||
153 | #define __abs_choose_expr(x, type, other) __builtin_choose_expr( \ | |
154 | __builtin_types_compatible_p(typeof(x), signed type) || \ | |
155 | __builtin_types_compatible_p(typeof(x), unsigned type), \ | |
156 | ({ signed type __x = (x); __x < 0 ? -__x : __x; }), other) | |
157 | ||
46f12960 AS |
158 | /** |
159 | * abs_diff - return absolute value of the difference between the arguments | |
160 | * @a: the first argument | |
161 | * @b: the second argument | |
162 | * | |
163 | * @a and @b have to be of the same type. With this restriction we compare | |
164 | * signed to signed and unsigned to unsigned. The result is the subtraction | |
165 | * the smaller of the two from the bigger, hence result is always a positive | |
166 | * value. | |
167 | * | |
168 | * Return: an absolute value of the difference between the @a and @b. | |
169 | */ | |
170 | #define abs_diff(a, b) ({ \ | |
171 | typeof(a) __a = (a); \ | |
172 | typeof(b) __b = (b); \ | |
173 | (void)(&__a == &__b); \ | |
174 | __a > __b ? (__a - __b) : (__b - __a); \ | |
175 | }) | |
176 | ||
aa6159ab AS |
177 | /** |
178 | * reciprocal_scale - "scale" a value into range [0, ep_ro) | |
179 | * @val: value | |
180 | * @ep_ro: right open interval endpoint | |
181 | * | |
182 | * Perform a "reciprocal multiplication" in order to "scale" a value into | |
183 | * range [0, @ep_ro), where the upper interval endpoint is right-open. | |
184 | * This is useful, e.g. for accessing a index of an array containing | |
185 | * @ep_ro elements, for example. Think of it as sort of modulus, only that | |
186 | * the result isn't that of modulo. ;) Note that if initial input is a | |
187 | * small value, then result will return 0. | |
188 | * | |
189 | * Return: a result based on @val in interval [0, @ep_ro). | |
190 | */ | |
191 | static inline u32 reciprocal_scale(u32 val, u32 ep_ro) | |
192 | { | |
193 | return (u32)(((u64) val * ep_ro) >> 32); | |
194 | } | |
195 | ||
196 | u64 int_pow(u64 base, unsigned int exp); | |
197 | unsigned long int_sqrt(unsigned long); | |
198 | ||
199 | #if BITS_PER_LONG < 64 | |
200 | u32 int_sqrt64(u64 x); | |
201 | #else | |
202 | static inline u32 int_sqrt64(u64 x) | |
203 | { | |
204 | return (u32)int_sqrt(x); | |
205 | } | |
206 | #endif | |
207 | ||
208 | #endif /* _LINUX_MATH_H */ |