| 1 |
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| 2 | #ifndef _LINUX_MATH_H
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| 3 | #define _LINUX_MATH_H
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| 4 |
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| 5 | #include <linux/types.h>
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| 6 | #include <asm/div64.h>
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| 7 | #include <uapi/linux/kernel.h>
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| 8 |
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| 9 | |
| 10 | * This looks more complex than it should be. But we need to
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| 11 | * get the type for the ~ right in round_down (it needs to be
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| 12 | * as wide as the result!), and we want to evaluate the macro
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| 13 | * arguments just once each.
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| 14 |
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| 15 | #define __round_mask(x, y) ((__typeof__(x))((y)-1))
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| 16 |
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| 17 | |
| 18 | * round_up - round up to next specified power of 2
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| 19 | * @x: the value to round
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| 20 | * @y: multiple to round up to (must be a power of 2)
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| 21 | *
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| 22 | * Rounds @x up to next multiple of @y (which must be a power of 2).
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| 23 | * To perform arbitrary rounding up, use roundup() below.
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| 24 |
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| 25 | #define round_up(x, y) ((((x)-1) | __round_mask(x, y))+1)
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| 26 |
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| 27 | |
| 28 | * round_down - round down to next specified power of 2
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| 29 | * @x: the value to round
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| 30 | * @y: multiple to round down to (must be a power of 2)
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| 31 | *
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| 32 | * Rounds @x down to next multiple of @y (which must be a power of 2).
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| 33 | * To perform arbitrary rounding down, use rounddown() below.
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| 34 |
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| 35 | #define round_down(x, y) ((x) & ~__round_mask(x, y))
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| 36 |
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| 37 | |
| 38 | * DIV_ROUND_UP_POW2 - divide and round up
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| 39 | * @n: numerator
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| 40 | * @d: denominator (must be a power of 2)
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| 41 | *
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| 42 | * Divides @n by @d and rounds up to next multiple of @d (which must be a power
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| 43 | * of 2). Avoids integer overflows that may occur with __KERNEL_DIV_ROUND_UP().
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| 44 | * Performance is roughly equivalent to __KERNEL_DIV_ROUND_UP().
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| 45 |
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| 46 | #define DIV_ROUND_UP_POW2(n, d) \
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| 47 | ((n) / (d) + !!((n) & ((d) - 1)))
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| 48 |
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| 49 | #define DIV_ROUND_UP __KERNEL_DIV_ROUND_UP
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| 50 |
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| 51 | #define DIV_ROUND_DOWN_ULL(ll, d) \
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| 52 | ({ unsigned long long _tmp = (ll); do_div(_tmp, d); _tmp; })
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| 53 |
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| 54 | #define DIV_ROUND_UP_ULL(ll, d) \
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| 55 | DIV_ROUND_DOWN_ULL((unsigned long long)(ll) + (d) - 1, (d))
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| 56 |
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| 57 | #if BITS_PER_LONG == 32
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| 58 | # define DIV_ROUND_UP_SECTOR_T(ll,d) DIV_ROUND_UP_ULL(ll, d)
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| 59 | #else
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| 60 | # define DIV_ROUND_UP_SECTOR_T(ll,d) DIV_ROUND_UP(ll,d)
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| 61 | #endif
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| 62 |
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| 63 | |
| 64 | * roundup - round up to the next specified multiple
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| 65 | * @x: the value to up
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| 66 | * @y: multiple to round up to
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| 67 | *
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| 68 | * Rounds @x up to next multiple of @y. If @y will always be a power
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| 69 | * of 2, consider using the faster round_up().
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| 70 |
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| 71 | #define roundup(x, y) ( \
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| 72 | { \
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| 73 | typeof(y) __y = y; \
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| 74 | (((x) + (__y - 1)) / __y) * __y; \
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| 75 | } \
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| 76 | )
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| 77 | |
| 78 | * rounddown - round down to next specified multiple
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| 79 | * @x: the value to round
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| 80 | * @y: multiple to round down to
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| 81 | *
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| 82 | * Rounds @x down to next multiple of @y. If @y will always be a power
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| 83 | * of 2, consider using the faster round_down().
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| 84 |
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| 85 | #define rounddown(x, y) ( \
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| 86 | { \
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| 87 | typeof(x) __x = (x); \
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| 88 | __x - (__x % (y)); \
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| 89 | } \
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| 90 | )
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| 91 |
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| 92 | #define DIV_ROUND_CLOSEST __KERNEL_DIV_ROUND_CLOSEST
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| 93 | |
| 94 | * Same as above but for u64 dividends. divisor must be a 32-bit
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| 95 | * number.
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| 96 |
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| 97 | #define DIV_ROUND_CLOSEST_ULL(x, divisor)( \
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| 98 | { \
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| 99 | typeof(divisor) __d = divisor; \
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| 100 | unsigned long long _tmp = (x) + (__d) / 2; \
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| 101 | do_div(_tmp, __d); \
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| 102 | _tmp; \
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| 103 | } \
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| 104 | )
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| 105 |
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| 106 | #define __STRUCT_FRACT(type) \
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| 107 | struct type##_fract { \
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| 108 | __##type numerator; \
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| 109 | __##type denominator; \
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| 110 | };
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| 111 | __STRUCT_FRACT(s8)
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| 112 | __STRUCT_FRACT(u8)
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| 113 | __STRUCT_FRACT(s16)
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| 114 | __STRUCT_FRACT(u16)
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| 115 | __STRUCT_FRACT(s32)
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| 116 | __STRUCT_FRACT(u32)
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| 117 | #undef __STRUCT_FRACT
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| 118 |
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| 119 |
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| 120 | #define mult_frac(x, n, d) \
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| 121 | ({ \
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| 122 | typeof(x) x_ = (x); \
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| 123 | typeof(n) n_ = (n); \
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| 124 | typeof(d) d_ = (d); \
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| 125 | \
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| 126 | typeof(x_) q = x_ / d_; \
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| 127 | typeof(x_) r = x_ % d_; \
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| 128 | q * n_ + r * n_ / d_; \
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| 129 | })
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| 130 |
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| 131 | #define sector_div(a, b) do_div(a, b)
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| 132 |
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| 133 | |
| 134 | * abs - return absolute value of an argument
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| 135 | * @x: the value.
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| 136 | *
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| 137 | * If it is unsigned type, @x is converted to signed type first.
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| 138 | * char is treated as if it was signed (regardless of whether it really is)
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| 139 | * but the macro's return type is preserved as char.
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| 140 | *
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| 141 | * NOTE, for signed type if @x is the minimum, the returned result is undefined
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| 142 | * as there is not enough bits to represent it as a positive number.
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| 143 | *
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| 144 | * Return: an absolute value of @x.
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| 145 |
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| 146 | #define abs(x) __abs_choose_expr(x, long long, \
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| 147 | __abs_choose_expr(x, long, \
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| 148 | __abs_choose_expr(x, int, \
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| 149 | __abs_choose_expr(x, short, \
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| 150 | __abs_choose_expr(x, char, \
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| 151 | __builtin_choose_expr( \
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| 152 | __builtin_types_compatible_p(typeof(x), char), \
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| 153 | (char)({ signed char __x = (x); __x<0?-__x:__x; }), \
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| 154 | ((void)0)))))))
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| 155 |
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| 156 | #define __abs_choose_expr(x, type, other) __builtin_choose_expr( \
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| 157 | __builtin_types_compatible_p(typeof(x), signed type) || \
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| 158 | __builtin_types_compatible_p(typeof(x), unsigned type), \
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| 159 | ({ signed type __x = (x); __x < 0 ? -__x : __x; }), other)
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| 160 |
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| 161 | |
| 162 | * abs_diff - return absolute value of the difference between the arguments
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| 163 | * @a: the first argument
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| 164 | * @b: the second argument
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| 165 | *
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| 166 | * @a and @b have to be of the same type. With this restriction we compare
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| 167 | * signed to signed and unsigned to unsigned. The result is the subtraction
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| 168 | * the smaller of the two from the bigger, hence result is always a positive
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| 169 | * value.
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| 170 | *
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| 171 | * Return: an absolute value of the difference between the @a and @b.
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| 172 |
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| 173 | #define abs_diff(a, b) ({ \
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| 174 | typeof(a) __a = (a); \
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| 175 | typeof(b) __b = (b); \
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| 176 | (void)(&__a == &__b); \
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| 177 | __a > __b ? (__a - __b) : (__b - __a); \
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| 178 | })
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| 179 |
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| 180 | |
| 181 | * reciprocal_scale - "scale" a value into range [0, ep_ro)
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| 182 | * @val: value
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| 183 | * @ep_ro: right open interval endpoint
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| 184 | *
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| 185 | * Perform a "reciprocal multiplication" in order to "scale" a value into
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| 186 | * range [0, @ep_ro), where the upper interval endpoint is right-open.
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| 187 | * This is useful, e.g. for accessing a index of an array containing
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| 188 | * @ep_ro elements, for example. Think of it as sort of modulus, only that
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| 189 | * the result isn't that of modulo. ;) Note that if initial input is a
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| 190 | * small value, then result will return 0.
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| 191 | *
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| 192 | * Return: a result based on @val in interval [0, @ep_ro).
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| 193 |
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| 194 | static inline u32 reciprocal_scale(u32 val, u32 ep_ro)
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| 195 | {
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| 196 | return (u32)(((u64) val * ep_ro) >> 32);
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| 197 | }
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| 198 |
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| 199 | u64 int_pow(u64 base, unsigned int exp);
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| 200 | unsigned long int_sqrt(unsigned long);
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| 201 |
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| 202 | #if BITS_PER_LONG < 64
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| 203 | u32 int_sqrt64(u64 x);
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| 204 | #else
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| 205 | static inline u32 int_sqrt64(u64 x)
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| 206 | {
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| 207 | return (u32)int_sqrt(x);
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| 208 | }
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| 209 | #endif
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| 210 |
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| 211 | #endif
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