Sorry, been there and done that.

-- Bob Ammerman

----- Original Message -----=20
From: "Isaac Marino Bavaresco" <isaacbavaresco@yahoo.com.br>
To: "Microcontroller discussion list - Public." <piclist@mit.edu>
Sent: Friday, January 20, 2012 11:48 AM
Subject: [PIC] New(?) way for rotating a variable number of positions=20
inassembly


>I was needing an (very) efficient way to rotate a byte a variable number
> of positions when the following popped on my mind:
>
>
>        btfsc    TABLAT, 2, ACCESS
>        swapf    PRODL, F, ACCESS
>        btfsc    TABLAT, 1, ACCESS
>        rrncf    PRODL, F, ACCESS
>        btfsc    TABLAT, 1, ACCESS
>        rrncf    PRODL, F, ACCESS
>        btfsc    TABLAT, 0, ACCESS
>        rrncf    PRODL, F, ACCESS
>
>
> The number of positions to rotate is in TABLAT and the value to be
> rotated is in PRODL.
> The routine can rotate from zero to 7 positions, takes only 8
> instructions and as a bonus it is isochronous.
>
> Did somebody already know it or can I boast that I invented it?
>
>
> Isaac
>
> --=20
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