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Message-ID: <72e1ed9c-9400-da54-71ce-ecd7ad97c174@uni-rostock.de>
Date:   Fri, 21 Apr 2023 15:06:14 +0200
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Subject: Re: [RFC] average: rewrite for clearity
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To:     <nbd@nbd.name>, <johannes@sipsolutions.net>,
        <linux-wireless@vger.kernel.org>
References: <20230421130022.191045-1-benjamin.beichler@uni-rostock.de>
From:   Benjamin Beichler <Benjamin.Beichler@uni-rostock.de>
Organization: =?UTF-8?Q?Universit=c3=a4t_Rostock?=
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Sorry for the crappy formatting of line endings, I have some tab/space 
issues with my editor, I will fix this ...

Am 21.04.2023 um 15:00 schrieb Benjamin Beichler:
> Move the former *=5Fadd function with its implicit initialization into a
> separate function, when the user explicitly wants to init with the first
> added value, altough this creates issues, when 0 is a expected value for
> the internal value.
>
> Add a separate init function with value parameter to allow init with
> distinct value, which was formerly done by the implicit init of old
> *=5Fadd function.
>
> Move the compile time checks into a separate macro, as they are used
> multiple times and noise up the functions.
>
> Also fix some formatting issues.
>
> Signed-off-by: Benjamin Beichler <benjamin.beichler@uni-rostock.de>
> ---
>   include/linux/average.h | 98 ++++++++++++++++++++++++-----------------
>   1 file changed, 57 insertions(+), 41 deletions(-)
>
> diff --git a/include/linux/average.h b/include/linux/average.h
> index a1a8f09631ce..2e70224b84a8 100644
> --- a/include/linux/average.h
> +++ b/include/linux/average.h
> @@ -25,47 +25,63 @@
>    * that this parameter must be a power of two for efficiency.
>    */
>   
> -#define DECLARE=5FEWMA(name, =5Fprecision, =5Fweight=5Frcp)=09=09=09\
> -=09struct ewma=5F##name {=09=09=09=09=09=09\
> -=09=09unsigned long internal;=09=09=09=09=09\
> -=09};=09=09=09=09=09=09=09=09\
> -=09static inline void ewma=5F##name##=5Finit(struct ewma=5F##name *e)=09\
> -=09{=09=09=09=09=09=09=09=09\
> -=09=09BUILD=5FBUG=5FON(!=5F=5Fbuiltin=5Fconstant=5Fp(=5Fprecision));=09\
> -=09=09BUILD=5FBUG=5FON(!=5F=5Fbuiltin=5Fconstant=5Fp(=5Fweight=5Frcp));=09\
> -=09=09/*=09=09=09=09=09=09=09\
> -=09=09 * Even if you want to feed it just 0/1 you should have=09\
> -=09=09 * some bits for the non-fractional part...=09=09\
> -=09=09 */=09=09=09=09=09=09=09\
> -=09=09BUILD=5FBUG=5FON((=5Fprecision) > 30);=09=09=09\
> -=09=09BUILD=5FBUG=5FON=5FNOT=5FPOWER=5FOF=5F2(=5Fweight=5Frcp);=09=09\
> -=09=09e->internal =3D 0;=09=09=09=09=09\
> -=09}=09=09=09=09=09=09=09=09\
> -=09static inline unsigned long=09=09=09=09=09\
> -=09ewma=5F##name##=5Fread(struct ewma=5F##name *e)=09=09=09\
> -=09{=09=09=09=09=09=09=09=09\
> -=09=09BUILD=5FBUG=5FON(!=5F=5Fbuiltin=5Fconstant=5Fp(=5Fprecision));=09\
> -=09=09BUILD=5FBUG=5FON(!=5F=5Fbuiltin=5Fconstant=5Fp(=5Fweight=5Frcp));=09\
> -=09=09BUILD=5FBUG=5FON((=5Fprecision) > 30);=09=09=09\
> -=09=09BUILD=5FBUG=5FON=5FNOT=5FPOWER=5FOF=5F2(=5Fweight=5Frcp);=09=09\
> -=09=09return e->internal >> (=5Fprecision);=09=09=09\
> -=09}=09=09=09=09=09=09=09=09\
> -=09static inline void ewma=5F##name##=5Fadd(struct ewma=5F##name *e,=09\
> -=09=09=09=09=09     unsigned long val)=09=09\
> -=09{=09=09=09=09=09=09=09=09\
> -=09=09unsigned long internal =3D READ=5FONCE(e->internal);=09\
> -=09=09unsigned long weight=5Frcp =3D ilog2(=5Fweight=5Frcp);=09=09\
> -=09=09unsigned long precision =3D =5Fprecision;=09=09=09\
> -=09=09=09=09=09=09=09=09=09\
> -=09=09BUILD=5FBUG=5FON(!=5F=5Fbuiltin=5Fconstant=5Fp(=5Fprecision));=09\
> -=09=09BUILD=5FBUG=5FON(!=5F=5Fbuiltin=5Fconstant=5Fp(=5Fweight=5Frcp));=09\
> -=09=09BUILD=5FBUG=5FON((=5Fprecision) > 30);=09=09=09\
> -=09=09BUILD=5FBUG=5FON=5FNOT=5FPOWER=5FOF=5F2(=5Fweight=5Frcp);=09=09\
> -=09=09=09=09=09=09=09=09=09\
> -=09=09WRITE=5FONCE(e->internal, internal =3F=09=09=09\
> -=09=09=09(((internal << weight=5Frcp) - internal) +=09\
> -=09=09=09=09(val << precision)) >> weight=5Frcp :=09\
> -=09=09=09(val << precision));=09=09=09=09\
> +#define EWMA=5FBUILD=5FTIME=5FCHECKS(=5Fprecision, =5Fweight=5Frcp)        =
                \
> +=09=09BUILD=5FBUG=5FON(!=5F=5Fbuiltin=5Fconstant=5Fp(=5Fprecision));=09=09=
=09=09=09   \
> +=09=09BUILD=5FBUG=5FON(!=5F=5Fbuiltin=5Fconstant=5Fp(=5Fweight=5Frcp));=09 =
                  \
> +=09=09/*=09=09=09=09=09=09=09                                           \
> +=09=09 * Even if you want to feed it just 0/1 you should have=09           =
    \
> +=09=09 * some bits for the non-fractional part...=09=09                    =
   \
> +=09=09 */=09=09=09=09=09=09=09=09=09=09=09=09=09=09=09=09=09   \
> +=09=09BUILD=5FBUG=5FON((=5Fprecision) > 30);=09=09=09=09=09=09=09=09=09   \
> +=09=09BUILD=5FBUG=5FON=5FNOT=5FPOWER=5FOF=5F2(=5Fweight=5Frcp);=09=09
> +
> +
> +#define DECLARE=5FEWMA(name, =5Fprecision, =5Fweight=5Frcp)=09=09=09       =
            \
> +=09struct ewma=5F##name {=09=09=09=09=09=09                               \
> +=09=09unsigned long internal;=09=09=09=09=09                               =
\
> +=09};=09=09=09=09=09=09=09=09                                           \
> +=09static inline void ewma=5F##name##=5Finit=5Fval(struct ewma=5F##name *e,=
           \
> +=09=09=09=09=09=09=09=09=09=09  unsigned long init)=09               \
> +=09{=09=09=09=09=09=09=09=09                                           \
> +=09=09EWMA=5FBUILD=5FTIME=5FCHECKS(=5Fprecision, =5Fweight=5Frcp)          =
              \
> +=09=09e->internal =3D init << =5Fprecision;=09=09=09=09=09                 =
  \
> +=09}=09=09=09=09=09=09=09=09                                           \
> +=09static inline void ewma=5F##name##=5Finit(struct ewma=5F##name *e)      =
         \
> +=09{=09                                                                    =
   \
> +=09=09=09ewma=5F##name##=5Finit=5Fval(e, 0);=09=09=09=09=09=09             =
  \
> +=09}                                                                       =
   \
> +=09static inline unsigned long=09=09=09=09=09                              =
 \
> +=09ewma=5F##name##=5Fread(struct ewma=5F##name *e)=09=09=09                =
       \
> +=09{=09=09=09=09=09=09=09=09                                           \
> +=09=09EWMA=5FBUILD=5FTIME=5FCHECKS(=5Fprecision, =5Fweight=5Frcp)          =
              \
> +=09=09return e->internal >> (=5Fprecision);=09=09=09                       =
    \
> +=09}=09=09=09=09=09=09=09=09                                           \
> +=09static inline void ewma=5F##name##=5Fadd(struct ewma=5F##name *e,=09    =
           \
> +=09=09=09=09=09     unsigned long val)=09=09                               =
\
> +=09{=09=09=09=09=09=09=09=09                                           \
> +=09=09unsigned long internal =3D READ=5FONCE(e->internal);=09              =
     \
> +=09=09unsigned long weight=5Frcp =3D ilog2(=5Fweight=5Frcp);=09=09         =
          \
> +=09=09unsigned long precision =3D =5Fprecision;=09=09=09                   =
    \
> +=09=09=09=09=09=09=09=09=09                                           \
> +=09=09EWMA=5FBUILD=5FTIME=5FCHECKS(=5Fprecision, =5Fweight=5Frcp)          =
              \
> +=09=09=09=09=09=09=09=09=09                                           \
> +=09=09WRITE=5FONCE(e->internal,=09=09=09                                   =
    \
> +=09=09=09(((internal << weight=5Frcp) - internal) +=09                     =
  \
> +=09=09=09=09(val << precision)) >> weight=5Frcp);=09=09                    =
   \
> +=09}                                                                       =
   \
> +=09static inline void ewma=5F##name##=5Fadd=5For=5Finit(struct ewma=5F##nam=
e *e,=09       \
> +=09=09=09=09=09     unsigned long val)=09=09                               =
\
> +=09{=09=09=09=09=09=09=09=09                                           \
> +=09=09unsigned long internal =3D READ=5FONCE(e->internal);=09              =
     \
> +=09=09unsigned long weight=5Frcp =3D ilog2(=5Fweight=5Frcp);=09=09         =
          \
> +=09=09unsigned long precision =3D =5Fprecision;=09=09=09                   =
    \
> +=09=09=09=09=09=09=09=09=09                                           \
> +=09=09EWMA=5FBUILD=5FTIME=5FCHECKS(=5Fprecision, =5Fweight=5Frcp)          =
              \
> +=09=09=09=09=09=09=09=09=09                                           \
> +=09=09WRITE=5FONCE(e->internal, internal =3F=09=09=09=09=09=09=09=09=09   \
> +=09=09=09(((internal << weight=5Frcp) - internal) +=09                     =
  \
> +=09=09=09=09(val << precision)) >> weight=5Frcp :=09                       =
    \
> +=09=09=09(val << precision));=09=09=09=09                               \
>   =09}
>   
>   #endif /* =5FLINUX=5FAVERAGE=5FH */


-- 
M.Sc. Benjamin Beichler

Universit=C3=A4t Rostock, Fakult=C3=A4t f=C3=BCr Informatik und Elektrotechnik
Institut f=C3=BCr Angewandte Mikroelektronik und Datentechnik

University of Rostock, Department of CS and EE
Institute of Applied Microelectronics and CE

Albert-Einstein-Str. 26
18059 Rostock
Deutschland/Germany

phone: +49 (0) 381 498 - 7278
email: Benjamin.Beichler@uni-rostock.de
www: http://www.imd.uni-rostock.de/