David E. Queen <PICLIST@MITVMA.MIT.EDU> wrote:

> I can save 600bytes in a lookup table if I can figure out a good way
> to divide a 16 bit number by 10.
>
> I have the app notes with the general 16 math, but I need a smaller
> and faster routine.

David:

Didn't I just post a divide-by-5 routine here?  Oh, well... Must have
been that other PIC list.

Here's a 16-bit divide-by-10 algorithm (y = x/10):

    y = x/4

    for i = 1 to 7
        y = x - y
        y = y/4
    next i

    y = y/2

This works for both signed and unsigned x; if you can deal with a
very slight rounding error, you can speed the routine up by iterating
only 5 times, rather than 7.

-Andy

Andrew Warren - fastfwd@ix.netcom.com
Fast Forward Engineering, Vista, California
http://www.geocities.com/SiliconValley/2499