Re: Access Key for a Sub File ?

"Stone, Brad V (PP)" wrote:
> 
> -----Original Message-----
> --snip--
> 
> P.S. BTW this can also be used to speed up LOKUP operations on an
> ordered array.
> 
> Any idea as to what search method a LOKUP (LOOKUP) uses?
> +---

Brad,

AFAIK, it does an entry by entry compare starting with the set index
value.

Sort of like:
                z-add   1       x
        arg     dowle ara,x
                add     1       x
                enddo

(or is that DOUGT ... now let's not revisit the DOW DOU wars! ) But I
hope you get the drift.

I have not reviewed generated code lately, but the last time I looked
into it, there was a high operation byte count (instructions executed)
therefore machine cycles used therefore slow execution.

Now I'm not even going to try to count spaces to do this, but typical
code would be: (RPGIII/400)

                        z-add   1       x       
                arg     lokup   ara,x           91  90 > or =

One could binary halve the array to set the initial value for "x" and
eliminate, some times, 25-50-75% of the array.

If the compiler now has an automatic halving technique for an array
defined as ascending or descending fill me in. Come to think of it, the
compiler *should* use halving for such an array.

IMHO, to mirror an ordered subfile key into an ordered array just adds
another layer of programmed synchronization and a potential for
failure.  The value is already in the subfile (in order), why take up
more resource to replicate?

Let's see, 9,999 potential elements per subfile times value length times
number of users or managing dynamic user space when about 50 lines of
code can do the job? I don't think so.

I was just about to post the code when I recalled a list guideline
against such, but if anyone would like a cloneable set of routines feel
free to contact me privately.

James W. Kilgore
email@James-W-Kilgore.com
+---
| This is the Midrange System Mailing List!
| To submit a new message, send your mail to MIDRANGE-L@midrange.com.
| To subscribe to this list send email to MIDRANGE-L-SUB@midrange.com.
| To unsubscribe from this list send email to MIDRANGE-L-UNSUB@midrange.com.
| Questions should be directed to the list owner/operator: david@midrange.com
+---