/* Exponentially weighted moving average (EWMA) */
-/* For more documentation see lib/average.c */
-
-struct ewma {
- unsigned long internal;
- unsigned long factor;
- unsigned long weight;
-};
-
-extern void ewma_init(struct ewma *avg, unsigned long factor,
- unsigned long weight);
-
-extern struct ewma *ewma_add(struct ewma *avg, unsigned long val);
-
-/**
- * ewma_read() - Get average value
- * @avg: Average structure
- *
- * Returns the average value held in @avg.
- */
-static inline unsigned long ewma_read(const struct ewma *avg)
-{
- return avg->internal >> avg->factor;
-}
+#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 */