Re: Infinit loop in /free

["Booth Martin" <Booth@xxxxxxxxxxxx>]

If you are trying to set a never ending loop then why not just dou 'cat'=
dog' ? Its immediately clear to anyone what you are doing. 

This *HIVAL thing doesn't have "forever" written all over it, and would
cause anyone that sees it the first time to find the field's  *HIVAL and ask
questions. For instance, look at the amount of confusion and discussion it
has generated here. Something similar must happen with every programmer that
sees this technique for the first time.
 
Besides that, why have a never ending loop? I thought goto, leave, iter,
CAS**, and CAB** were all opcodes that had been disgraced and sent into
exile? 
  
---------------------------------------------------------
Booth Martin http://www.MartinVT.com
Booth@xxxxxxxxxxxx
---------------------------------------------------------
 
-------Original Message-------
 
From: RPG programming on the AS400 / iSeries
Date: 11/21/2003 10:47:01 AM
To: rpg400-l@xxxxxxxxxxxx
Subject: Re: Infinit loop in /free
 
Steve Richter wrote:
 
> well I just had to test this ( comparing a count to a 31 digit packed
> decimal hival number seems a bit wasteful ) ...
>
> the following million iteration loop runs for 63 milliseconds on a
170/2386
> ( 400+ cpw ):
> ...
>
> and this do *hival version runs for 390 milliseconds
> ...
>
> -Steve
>
 
So this means that in a loop that does nothing, a DOW loop is preferable
to DO *HIVAL. In practice, most loops do a bit more than that, and so
the difference in loop overhead is usually swamped by the operations
within the loop.
 
But the comparison itself is flawed. The former uses a 10I0 variable as
loop index, the latter uses an implicitly defined decimal variable with
a precision of 31 digits. To make the comparison fair, define IX as 31P0
in the first program.
 
Out of curiosity, let's examine this result further. For the latter
program, "DO *HIVAL" runs about 3 million iterations per second. If we
let the program run for *HIVAL iterations, how long will we have to wait
for the loop to end? My calculations show we'll have to wait, oh, about
a hundred million billion years. ;-)
 
Cheers! Hans