| Bruno Randolf | c5485a7 | 2010-11-16 10:58:37 +0900 | [diff] [blame] | 1 | #ifndef _LINUX_AVERAGE_H |
| 2 | #define _LINUX_AVERAGE_H |
| 3 | |
| Bruno Randolf | c5485a7 | 2010-11-16 10:58:37 +0900 | [diff] [blame] | 4 | /* Exponentially weighted moving average (EWMA) */ |
| 5 | |
| 6 | /* For more documentation see lib/average.c */ |
| 7 | |
| 8 | struct ewma { |
| 9 | unsigned long internal; |
| 10 | unsigned long factor; |
| 11 | unsigned long weight; |
| 12 | }; |
| 13 | |
| 14 | extern void ewma_init(struct ewma *avg, unsigned long factor, |
| 15 | unsigned long weight); |
| 16 | |
| 17 | extern struct ewma *ewma_add(struct ewma *avg, unsigned long val); |
| 18 | |
| 19 | /** |
| 20 | * ewma_read() - Get average value |
| 21 | * @avg: Average structure |
| 22 | * |
| 23 | * Returns the average value held in @avg. |
| 24 | */ |
| 25 | static inline unsigned long ewma_read(const struct ewma *avg) |
| 26 | { |
| Bruno Randolf | af55688 | 2010-12-02 19:50:37 +0900 | [diff] [blame] | 27 | return avg->internal >> avg->factor; |
| Bruno Randolf | c5485a7 | 2010-11-16 10:58:37 +0900 | [diff] [blame] | 28 | } |
| 29 | |
| Johannes Berg | 2377799 | 2015-07-13 12:17:25 +0200 | [diff] [blame^] | 30 | #define DECLARE_EWMA(name, _factor, _weight) \ |
| 31 | struct ewma_##name { \ |
| 32 | unsigned long internal; \ |
| 33 | }; \ |
| 34 | static inline void ewma_##name##_init(struct ewma_##name *e) \ |
| 35 | { \ |
| 36 | BUILD_BUG_ON(!__builtin_constant_p(_factor)); \ |
| 37 | BUILD_BUG_ON(!__builtin_constant_p(_weight)); \ |
| 38 | BUILD_BUG_ON_NOT_POWER_OF_2(_factor); \ |
| 39 | BUILD_BUG_ON_NOT_POWER_OF_2(_weight); \ |
| 40 | e->internal = 0; \ |
| 41 | } \ |
| 42 | static inline unsigned long \ |
| 43 | ewma_##name##_read(struct ewma_##name *e) \ |
| 44 | { \ |
| 45 | BUILD_BUG_ON(!__builtin_constant_p(_factor)); \ |
| 46 | BUILD_BUG_ON(!__builtin_constant_p(_weight)); \ |
| 47 | BUILD_BUG_ON_NOT_POWER_OF_2(_factor); \ |
| 48 | BUILD_BUG_ON_NOT_POWER_OF_2(_weight); \ |
| 49 | return e->internal >> ilog2(_factor); \ |
| 50 | } \ |
| 51 | static inline void ewma_##name##_add(struct ewma_##name *e, \ |
| 52 | unsigned long val) \ |
| 53 | { \ |
| 54 | unsigned long internal = ACCESS_ONCE(e->internal); \ |
| 55 | unsigned long weight = ilog2(_weight); \ |
| 56 | unsigned long factor = ilog2(_factor); \ |
| 57 | \ |
| 58 | BUILD_BUG_ON(!__builtin_constant_p(_factor)); \ |
| 59 | BUILD_BUG_ON(!__builtin_constant_p(_weight)); \ |
| 60 | BUILD_BUG_ON_NOT_POWER_OF_2(_factor); \ |
| 61 | BUILD_BUG_ON_NOT_POWER_OF_2(_weight); \ |
| 62 | \ |
| 63 | ACCESS_ONCE(e->internal) = internal ? \ |
| 64 | (((internal << weight) - internal) + \ |
| 65 | (val << factor)) >> weight : \ |
| 66 | (val << factor); \ |
| 67 | } |
| 68 | |
| Bruno Randolf | c5485a7 | 2010-11-16 10:58:37 +0900 | [diff] [blame] | 69 | #endif /* _LINUX_AVERAGE_H */ |