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From: amead@s.psych.uiuc.edu (alan mead)
Newsgroups: comp.lang.pascal
Subject: need a little flexibility
Message-ID: <1991Apr24.183315.7997@ux1.cso.uiuc.edu>
Date: 24 Apr 91 18:33:15 GMT
Sender: usenet@ux1.cso.uiuc.edu (News)
Organization: University of Illinois at Urbana
Lines: 36

Hi.  I want to manipulate a data structure in the cleanest way possible 
(after I write this, I'd like to minimize maintenance time).  I've been
working with something like this:

Block = record
       x    : byte;
       y    : byte;
       ...
       data : array[1..252] of byte;
end;

but the elements of data are sometimes words instead of bytes and this
structure doesn't compile (I guess you cannot declare ABSOLUTE structures
in a type declaration?):

Block = record
       x    : byte;
       y    : byte;
       ...
       data : array[1..252] of byte;
       dataW: array[1..126] of word ABSOLUTE data;
end;

If it did work, then I could assign words to DataW[ index*2 ] and bytes to 
Data[] just like Port & PortW and Mem and MemW.

But it doesn't.  I could declare the variables individually, but that
will probably cause confusion (ie, I'd rather use a record, and I don't
think I can declare a variable ABSOLUTE to a field in a record, and
even then it would be confusing).

And a variant record requires an exhaustive listing of it's fields right?

Any ideas?  Thanks much.

-alan : amead@s.psych.uiuc.edu