diff options
author | Bruno Randolf <br1@einfach.org> | 2010-11-16 10:58:37 +0900 |
---|---|---|
committer | John W. Linville <linville@tuxdriver.com> | 2010-11-18 14:21:52 -0500 |
commit | c5485a7e7569ab32eea240c850198519e2a765ef (patch) | |
tree | 928a8556deaec0811d1b83102b33365aab28a270 /include/linux/average.h | |
parent | 50a9432daeece6fc1309bef1dc0a7b8fde8204cb (diff) | |
download | linux-stable-c5485a7e7569ab32eea240c850198519e2a765ef.tar.gz linux-stable-c5485a7e7569ab32eea240c850198519e2a765ef.tar.bz2 linux-stable-c5485a7e7569ab32eea240c850198519e2a765ef.zip |
lib: Add generic exponentially weighted moving average (EWMA) function
This adds generic functions for calculating Exponentially Weighted Moving
Averages (EWMA). This implementation makes use of a structure which keeps the
EWMA parameters and a scaled up internal representation to reduce rounding
errors.
The original idea for this implementation came from the rt2x00 driver
(rt2x00link.c). I would like to use it in several places in the mac80211 and
ath5k code and I hope it can be useful in many other places in the kernel code.
Signed-off-by: Bruno Randolf <br1@einfach.org>
Reviewed-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
Diffstat (limited to 'include/linux/average.h')
-rw-r--r-- | include/linux/average.h | 32 |
1 files changed, 32 insertions, 0 deletions
diff --git a/include/linux/average.h b/include/linux/average.h new file mode 100644 index 000000000000..7706e40f95fa --- /dev/null +++ b/include/linux/average.h @@ -0,0 +1,32 @@ +#ifndef _LINUX_AVERAGE_H +#define _LINUX_AVERAGE_H + +#include <linux/kernel.h> + +/* 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 DIV_ROUND_CLOSEST(avg->internal, avg->factor); +} + +#endif /* _LINUX_AVERAGE_H */ |