51 lines
1.4 KiB
C
51 lines
1.4 KiB
C
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/*
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* Copyright 2010 Hauke Mehrtens <hauke@hauke-m.de>
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*
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* Compatibility file for Linux wireless for kernels 2.6.38.
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*/
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#include <linux/compat.h>
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#include <linux/module.h>
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#include <linux/bug.h>
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/**
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* ewma_init() - Initialize EWMA parameters
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* @avg: Average structure
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* @factor: Factor to use for the scaled up internal value. The maximum value
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* of averages can be ULONG_MAX/(factor*weight).
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* @weight: Exponential weight, or decay rate. This defines how fast the
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* influence of older values decreases. Has to be bigger than 1.
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*
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* Initialize the EWMA parameters for a given struct ewma @avg.
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*/
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void compat_ewma_init(struct ewma *avg, unsigned long factor, unsigned long weight)
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{
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WARN_ON(weight <= 1 || factor == 0);
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avg->internal = 0;
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avg->weight = weight;
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avg->factor = factor;
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}
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EXPORT_SYMBOL_GPL(compat_ewma_init);
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/**
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* ewma_add() - Exponentially weighted moving average (EWMA)
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* @avg: Average structure
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* @val: Current value
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*
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* Add a sample to the average.
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*/
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struct ewma *compat_ewma_add(struct ewma *avg, unsigned long val)
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{
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avg->internal = avg->internal ?
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(((avg->internal * (avg->weight - 1)) +
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(val * avg->factor)) / avg->weight) :
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(val * avg->factor);
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return avg;
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}
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EXPORT_SYMBOL_GPL(compat_ewma_add);
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