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- #ifndef _LINUX_AVERAGE_H
- #define _LINUX_AVERAGE_H
- /* Exponentially weighted moving average (EWMA) */
- #define DECLARE_EWMA(name, _factor, _weight) \
- struct ewma_##name { \
- unsigned long internal; \
- }; \
- static inline void ewma_##name##_init(struct ewma_##name *e) \
- { \
- BUILD_BUG_ON(!__builtin_constant_p(_factor)); \
- BUILD_BUG_ON(!__builtin_constant_p(_weight)); \
- BUILD_BUG_ON_NOT_POWER_OF_2(_factor); \
- BUILD_BUG_ON_NOT_POWER_OF_2(_weight); \
- e->internal = 0; \
- } \
- static inline unsigned long \
- ewma_##name##_read(struct ewma_##name *e) \
- { \
- BUILD_BUG_ON(!__builtin_constant_p(_factor)); \
- BUILD_BUG_ON(!__builtin_constant_p(_weight)); \
- BUILD_BUG_ON_NOT_POWER_OF_2(_factor); \
- BUILD_BUG_ON_NOT_POWER_OF_2(_weight); \
- return e->internal >> ilog2(_factor); \
- } \
- static inline void ewma_##name##_add(struct ewma_##name *e, \
- unsigned long val) \
- { \
- unsigned long internal = ACCESS_ONCE(e->internal); \
- unsigned long weight = ilog2(_weight); \
- unsigned long factor = ilog2(_factor); \
- \
- BUILD_BUG_ON(!__builtin_constant_p(_factor)); \
- BUILD_BUG_ON(!__builtin_constant_p(_weight)); \
- BUILD_BUG_ON_NOT_POWER_OF_2(_factor); \
- BUILD_BUG_ON_NOT_POWER_OF_2(_weight); \
- \
- ACCESS_ONCE(e->internal) = internal ? \
- (((internal << weight) - internal) + \
- (val << factor)) >> weight : \
- (val << factor); \
- }
- #endif /* _LINUX_AVERAGE_H */
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