Re: [MI400] More fun with nullmaps

["Steve Richter" <srichter@xxxxxxxxxxxxx>]

James,

Have you coded an rpg400 pgm that reads and writes to a file with ALWNULL,
compiled it with the *LIST, *XREF options and then looked at the resuling
irp code?

I am unclear on what the null map is and when it is used. Could you try to
explain it?

Steve Richter

----- Original Message -----
From: <jamesl@hb.quik.com>
To: <mi400@midrange.com>
Sent: Monday, November 12, 2001 7:58 AM
Subject: [MI400] More fun with nullmaps


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> From: jamesl@hb.quik.com
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> Date: Mon, 12 Nov 2001 12:58:41 AST
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> Subject: More fun with nullmaps
>
> Ladies and gentlemen, fellow geeks, geekettes, and gurus:
>
> So far, I've
> managed to determine that, in an input buffer for a file opened
> for all
> modes (i.e., Input, Output, Update, and Delete bits are set), there's a
> gap
> between te record and the nullmap, and I've empirically determined that
> it's
> eleven bytes, plus one byte per keyfield, plus one byte per key byte. So
>
> far, though, I can't explain the gap, except that it appears to have
nothing
> to
> do with variable length, since it occurs in files with no variable length
>
> fields, and none of the bits for including a "variable length access
> component"
> are set.
>
> Unfortunately, none of the obvious places (i.e., in
> the input buffer with the
> usual gap, in the output buffer with no gap [like
> Mr. Gaunt's demo program], in
> the output buffer with the usual gap) for
> sticking a nullmap seem to work for
> writing new records to the file. They
> all seem to be ignored.
>
> Any suggestions, either for explaining the gap, or
> for where the nullmap should
> go when writing new records under these
> conditions?
>
> Apologies for any funky
> formatting
>
> --
> J.Lampert
>
>
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