Andries Tip wrote:
> ;------------------------------------------------------------------------=
----
> ; 1:256 Finite Impuls Response Filter for 16-bit values - Andries Tip 201=
2
> ;------------------------------------------------------------------------=
----

[snip]

> ;------------------------------------------------------------------------=
----
>=20
> FIR_256_16BIT                   ; average =3D (255*average + setpoint)/25=
6
>=20
>         movf    average0,w      ; average =3D 256*average - average =3D 2=
55*average
>         sublw   d'0'            ; prepare carry
>         movwf   temp            ; save value for rounding later, otherwis=
e we cannot reach 65535
>         movf    average1,w      ;
>         subwfb  average0,f      ;
>         movf    average2,w      ;
>         subwfb  average1,f      ;
>         movlw   d'0'            ;
>         subwfb  average2,f      ;
>=20
>         movlw   d'255'          ; average =3D round((average + setpoint)/=
256)
>         addwf   temp,w          ;
>         movf    setpoint1,w     ;
>         addwfc  average0,f      ;
>         movf    setpoint2,w     ;
>         addwfc  average1,f      ;
>         clrw                    ;
>         addwfc  average2,f      ;
>=20
> ;------------------------------------------------------------------------=
----

This is NOT an FIR filter; it's a straight single-pole recursive (IIR) filt=
er.

-- Dave Tweed
--=20
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