RE: Basing Pointers

No, that is the reverse of what I want to do.

Basically what I am doing in using /COPY to copy the data structures
defined for the OS/400 API's into  my program, which are held in
QRPGLESRC in QSYSINC.
If I want to set pointers up for each data structure for a particular
API, I would have to amend that source. The problem with that is that
the QSYSINC library will be possibly updated at each upgrade.
Now you may ask, why do I need to set up a pointer to each DS for a
particular API. 

Basically because I assume that setting a pointer would be faster than
%SUBST.
If you only have a pointer to a userspace, you would currently:  

 D APIdatastructure  DS
   
 D DSSpaceVar   S   32767      Based(SpcPtr)

 C         DO    Noofdataitems
 C         Eval  APIdatastructure =
%SUBST(DSSpaceVar:1:%LEN(APIdatastructure))     Put Data Item into
datastructure
 C         EXSR PROCES
Process Data Item
 C         Eval SpcPtr = SpcPtr + NextItemOffset
Set Var to Next Data Item
 C         Enddo


But what I would like to be able to do, taking the assumption that it
would be quicker is:

 D APIdatastructure  DS

 D Ptr  *
Pointer to User Space

 C         Eval  SpcPtr = Ptr + Offset
Set Pointer To First Data Item

 C         DO    Noofdataitems
 C         Eval  %ADDR(APIdatastructure) = SpcPtr
Put Data Item into datastructure
 C         EXSR PROCES
Process Data Item
 C         Eval SpcPtr = SpcPtr + NextItemOffset
Set Var to Next Data Item
 C         Enddo

I am assuming here that using pointers is much faster that substringing
charcter strings

Correct me if I am wrong, I am here to be enlightened.


 

-----Original Message-----
From: Jon.Paris@halinfo.it [mailto:Jon.Paris@halinfo.it]
Sent: Friday, May 14, 1999 12:51 PM
To: MIDRANGE-L@midrange.com
Subject: Basing Pointers




 >> What I want is to be able to assign this at run time eg:

 >> EVAL %ADDR(DSdatastructure)=Ptr

Since you can already do this simply by coding like this:

 D DSdatastructure   DS                   Based(DS@)

 D         Eval  DS@ = Ptr

I really don't see the point.  It would also I suspect be a major cause
of
errors since looking at the DS definition would give you no hint that it
was
subject to moving around the universe!!


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