What does a simple bit-shifting routine look like and how does it work.

Most division examples on the piclist are confusing to me.

I need a real basic example I can reverse engineer and understand.




-----Original Message-----
From: Drew Vassallo [mailto:snurple@HOTMAIL.COM]
Sent: Monday, February 04, 2002 11:44 AM
To: PICLIST@MITVMA.MIT.EDU
Subject: Re: [PIC]:Help! How do can I do simple division?


>For example, I have a number between 0 and 255 and I want to know how many
>times 10 can be divided into the number.
>Is there a simple way to achieve this?

Check out www.piclist.com and look for Nikolai's code generator for
multiplication and division by a constant (in your case, 10).

If you're not into REAL multiplication and division, you can always do this
(I suppose this technique would qualify as "simple"):

                clrf    Temp
Div_By_10
                movlw   0x0A
                subwf   Your_Number, W
                btfss   STATUS, C
                goto    Done
                incf    Temp, F
                movwf   Your_Number
                goto    Div_By_10
Done
.....

at the end, "Temp" holds the whole number of times that your number is
divided by 10.

Note that I do not recommend this method, but it is worth mentioning that it
IS a valid division method.  It's just not nearly as fast in general as a
real bit-shifting routine.

--Andrew

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