RE: Extract variable string from a based DS using a pointer

Are you trying to simulate a VARYING field? Looks like it to me.

D TextDS    DS                       BASED(textPtr)
D  TextLen                     5I 0
D  TextData                32766A


If you use BASED, no storage is allocated for TEXTDS, so it does not matter
if you declare TEXTDATA as a 32K variable. That way SUBST and other
operation will work the way you want.

If you want to NOT use this suggestion, and you simply want to copy from
that memory location, use this:

  Eval     memcpy(%addr(target) : textPtr + 2: some-length-here )



But why not just use a VARYING field?

-Bob



-----Original Message-----
From: rpg400-l-bounces@xxxxxxxxxxxx [mailto:rpg400-l-bounces@xxxxxxxxxxxx]
On Behalf Of Dave Murvin
Sent: Thursday, December 16, 2004 5:29 PM
To: rpg400-l@xxxxxxxxxxxx
Subject: Extract variable string from a based DS using a pointer

HI,

I trying to extract a variable string from a data structure like the
following:

DTextDS          DS                  Based(TextPtr)
D TextLen                  1      2B 
0 

  *TEXTData                3      3

Note that TEXTData is not even defined at this point.

What I know is the value of the Text Pointer and the length of the text 
data (from TextLen).  I am having a hard time trying to figure out how to 
retrieve the text string from this structure into a variable character 
field that I can work with.  The TEXTData field should not even need to be 
defined in the DS as long as I know the address where it starts and how 
long it is.  Compiler did not like %Subst(TextDS : 3 : TextLen) because 3 
is larger than the defined DS.

I am just not seeing the solution to this.  I am trying to do this without 
having to specify a specific length to the TEXTData field or the DS.  I was 
thinking there must be some sort of C function that lets be extract from 
memory into a string, but I haven't found it yet.   Something like give me 
the string at TextPtr + 2 for TextLen positions.

Suggestions?

Thanks


Dave Murvin
DRM Enterprises, Inc.


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