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c5485a7e BR |
1 | #ifndef _LINUX_AVERAGE_H |
2 | #define _LINUX_AVERAGE_H | |
3 | ||
c5485a7e BR |
4 | /* Exponentially weighted moving average (EWMA) */ |
5 | ||
2377799c JB |
6 | #define DECLARE_EWMA(name, _factor, _weight) \ |
7 | struct ewma_##name { \ | |
8 | unsigned long internal; \ | |
9 | }; \ | |
10 | static inline void ewma_##name##_init(struct ewma_##name *e) \ | |
11 | { \ | |
12 | BUILD_BUG_ON(!__builtin_constant_p(_factor)); \ | |
13 | BUILD_BUG_ON(!__builtin_constant_p(_weight)); \ | |
14 | BUILD_BUG_ON_NOT_POWER_OF_2(_factor); \ | |
15 | BUILD_BUG_ON_NOT_POWER_OF_2(_weight); \ | |
16 | e->internal = 0; \ | |
17 | } \ | |
18 | static inline unsigned long \ | |
19 | ewma_##name##_read(struct ewma_##name *e) \ | |
20 | { \ | |
21 | BUILD_BUG_ON(!__builtin_constant_p(_factor)); \ | |
22 | BUILD_BUG_ON(!__builtin_constant_p(_weight)); \ | |
23 | BUILD_BUG_ON_NOT_POWER_OF_2(_factor); \ | |
24 | BUILD_BUG_ON_NOT_POWER_OF_2(_weight); \ | |
25 | return e->internal >> ilog2(_factor); \ | |
26 | } \ | |
27 | static inline void ewma_##name##_add(struct ewma_##name *e, \ | |
28 | unsigned long val) \ | |
29 | { \ | |
30 | unsigned long internal = ACCESS_ONCE(e->internal); \ | |
31 | unsigned long weight = ilog2(_weight); \ | |
32 | unsigned long factor = ilog2(_factor); \ | |
33 | \ | |
34 | BUILD_BUG_ON(!__builtin_constant_p(_factor)); \ | |
35 | BUILD_BUG_ON(!__builtin_constant_p(_weight)); \ | |
36 | BUILD_BUG_ON_NOT_POWER_OF_2(_factor); \ | |
37 | BUILD_BUG_ON_NOT_POWER_OF_2(_weight); \ | |
38 | \ | |
39 | ACCESS_ONCE(e->internal) = internal ? \ | |
40 | (((internal << weight) - internal) + \ | |
41 | (val << factor)) >> weight : \ | |
42 | (val << factor); \ | |
43 | } | |
44 | ||
c5485a7e | 45 | #endif /* _LINUX_AVERAGE_H */ |