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