Re: API receiver variable limit

[bmorris@xxxxxxxxxx]

>Date: Thu, 28 Sep 2000 11:43:46 -0400
>From: Buck Calabro <buck.calabro@aptissoftware.com>
>
>I'm writing a boilerplate for QDBRTVFD (Retrieve file description API).
The
>maximum RPG IV string size is 32kb.  The FILD0200 request for a particular
>file is returning 49kb of data.  I've used a multiple occurrence data
>structure and a based pointer to move an internal data structure around
>(which works), but can I rely on the compiler always storing the
occurrences
>one after the other (to form one block of contiguous API populated
memory?)
>Is there a better way? (I hope so!)  Should I use C? (sigh)

Buck, a multiple occurrence data structure always has contiguous
occurrences.  It must, in case the data structure is passed as a parm,
and for debuggers to work.  Oh, by the way, the maximum length of
a field and I think also a data structure, is 65535, starting in V4R2.

But this is a perfect place to use allocated storage.  Call the API once
with a tiny receiver to find out how much storage you need, then allocate
the storage and call it again.  Do your stuff, then deallocate.

D basicRcvr       ds
D                        10i 0
D   rcvrLen              10i 0

D QDBRV           ds             based(pQDBRV)
D   subfields ...

C       callp     QDBRTVFD (basicRcvr : %size(basicRcvr) : ...
C       alloc(e)  rcvrLen           pQDBRV
C       if        %error
C        ... oops ... storage not available ...
C       endif
C       callp     QDBRTVFD (QDBRV : rcvrLen : ...
C       do your stuff
C       dealloc                     pQDBRV

Another way to handle it is to declare your basicRcvr with some
"normal" length, and only do the allocation/deallocation if the
required length is longer.

C       callp     QDBRTVFD (basicRcvr ...
C       if        rcvrLen > %size(basicRcvr)
C       alloc(e) ... %error etc ...
C       callp     QDBRTVFD (QDBRV : rcvrLen : ...
C       eval      needToDealloc = *ON
C       else
C       eval      pQDBRV = %addr(basicRcvr)
C       endif
C       do your stuff
C       if        needToDealloc
C       dealloc                     pQDBRV
C       endif

Barbara Morris


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