Pointer not set on returning from an RPG procedure to a CL one.

["McCallion, Martin" <MccalliM@xxxxxxxxxxxxxxxx>]

Hi all.

This is weird.

I was typing up this message, and before I completed it, I tried
something out which fixed the problem.  But I thought I'd share it with
the list anyway, as I don't understand it.

Here's my original question:

I have a simple RPG procedure which returns a one-character value (*on
or *off, but that doesn't seem to be relevant, as I get the same problem
if I code a literal '1' or '0').  I'm calling it from a CL procedure,
using CALLPRC with the RTNVAL parameter.  The field for RTNVAL is
defined as *CHAR 1.

I get MCH3601, pointer not set for location referenced, on the RETURN
opcode.  Neither debug nor a dump tells me anything.

We are on V4R3.  Anybody got any ideas?

*** End of original question ***

And then I prompted CALLPRC and hit help on RTNVAL; it mentioned the
return value being 'aligned on a sixteen-byte boundary'.  So on an
impulse I redefined my return value field as *char 16.  And it worked.

I've come across this 'aligned on a sixteen-byte boundary' expression
before, and never understood it; I eventually had concluded that it was
a fancy way of saying pointers are sixteen bytes long; but I see that
there's more to it than that.  Can anybody explain what's going on here?

Cheers,

Martin.

--                                                                     
Martin McCallion                 
Midas-Kapiti International
Work:  mccallim@midas-kapiti.com
Home: martin.mccallion@ukonline.co.uk

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