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1 | // SPDX-License-Identifier: GPL-2.0 | |
2 | #include <linux/kernel.h> | |
3 | #include <asm/div64.h> | |
4 | #include <linux/reciprocal_div.h> | |
5 | #include <linux/export.h> | |
6 | ||
7 | /* | |
8 | * For a description of the algorithm please have a look at | |
9 | * include/linux/reciprocal_div.h | |
10 | */ | |
11 | ||
12 | struct reciprocal_value reciprocal_value(u32 d) | |
13 | { | |
14 | struct reciprocal_value R; | |
15 | u64 m; | |
16 | int l; | |
17 | ||
18 | l = fls(d - 1); | |
19 | m = ((1ULL << 32) * ((1ULL << l) - d)); | |
20 | do_div(m, d); | |
21 | ++m; | |
22 | R.m = (u32)m; | |
23 | R.sh1 = min(l, 1); | |
24 | R.sh2 = max(l - 1, 0); | |
25 | ||
26 | return R; | |
27 | } | |
28 | EXPORT_SYMBOL(reciprocal_value); |