Re: CL pgm and pointer variables

[Scott Klement <klemscot@xxxxxxxxxxxx>]

If I recall correctly, pointers in OS/400 have special tag bits in memory
which are only set if they're manipulated using the MI or W-Code
operations designed for working with pointers.

If the CL program defines it as a character variable, those bits would not
be set correctly, and the system would refuse to treat it as a pointer.

You could, of course, write the program and then use STRSST to edit the
compiled machine code so that it treated these bits correctly, but that
would require a very low-level knowledge of the system, plus you'd have
to do it EVERY time you recompiled the program.

Really, you're MUCH MUCH better off using a language that's capable of
working with pointers.

And since this is the RPG list, I'll recommend RPG :)



On Tue, 19 Nov 2002, Ken Sims wrote:

> Hi Hans and Michel -
>
> > > The 3 types of variables someone can define with DCL (*DEC, *CHAR,
> > > *LGL) don't suit my needs. Is there another way to declare variables ?
> >
> >I wouldn't count on it. If CL doesn't know a string of bytes can
> >contain a pointer, then the fact that it is a pointer value would be
> >lost.
>
> If CL character variables are aligned on a 16-byte boundary, then if you
> just receive the value from one procedure and pass it to another without
> manipulating it, you should be okay.
>
> The question then is, are CL character variables aligned on a 16-byte 
>boundary?
>
> Since you talk about calling procedures rather than programs, I assume that
> this is a program created from an ILE CL module.  That being the case, I
> think the translator should put a 16-byte character variable on a 16-byte
> boundary for you.
>
> Ken
> Opinions expressed are my own and do not necessarily represent the views of
> my employer or anyone in their right mind.
>