Re: RPG400-L Digest V2 #357

Hi Richard,

Where can I see the virtual address? I heard that the RPG ILE compiler no
longer has an option to print the MI. Is a pointer a virtual address? If so,
I could move the pointer to a 16-byte field and look at the low-order byte?

Regards,
Peter Dow
Dow Software Services, Inc.
909 425-0194 voice
909 425-0196 fax



----- Original Message -----
From: "Richard Jackson" <richardjackson@richardjackson.net>
To: <RPG400-L@midrange.com>
Sent: Tuesday, October 10, 2000 4:05 PM
Subject: RE: RPG400-L Digest V2 #357


> look at the virtual address of the object in storage.  If the low-order
byte
> of the address is a zero, the object is 16-byte aligned.  If the low order
> address byte is even (0, 2, 4, ...) the object is at least 2-byte aligned.
> And so forth.
>
> Richard Jackson
> mailto:richardjackson@richardjackson.net
> http://www.richardjacksonltd.com
> Voice: 1 (303) 808-8058
> Fax:   1 (303) 663-4325
>
> -|-----Original Message-----
> -|From: owner-rpg400-l@midrange.com [mailto:owner-rpg400-l@midrange.com]On
> -|Behalf Of Peter Dow
> -|Sent: Tuesday, October 10, 2000 1:27 PM
> -|To: RPG400-L@midrange.com
> -|Subject: Re: RPG400-L Digest V2 #357
> -|
> -|
> -|Hi Ken,
> -|
> -|How can one tell what boundary a data structure, or any other
> -|field for that
> -|matter, is aligned on?
> -|
> -|Curious,
> -|Peter Dow
> -|Dow Software Services, Inc.
> -|909 425-0194 voice
> -|909 425-0196 fax
> -|
> -|----- Original Message -----
> -|From: "Sims, Ken" <KSIMS@SOUTHERNWINE.com>
> -|To: <rpg400-l@midrange.com>
> -|Sent: Tuesday, October 10, 2000 10:08 AM
> -|Subject: RE: RPG400-L Digest V2 #357
> -|
> -|
> -|> Hi Peter -
> -|>
> -|> >The V4R4 RPG ILE manual says:
> -|>  ...
> -|> >The position they're talking about is the position of the
> -|subfield within
> -|a
> -|> >data structure, so if the above is true, one would have to assume
that
> -|the
> -|> >data structure begins on a 16-byte boundary. It would be nice if they
> -|> >explicitly said that, and assured us it won't change from release to
> -|> >release.
> -|>
> -|> Based on my experimentation, since the compiler rejects pointers
defined
> -|> with from/to positioning that is not on a 16-byte boundary, it appears
> -|that
> -|> data structures with pointers are always aligned on a 16-byte
boundary.
> -|> Only pointer fields *have* to be aligned on a 16-byte boundary.
> -| No other
> -|> fields *have* to be aligned on any particular boundary, and no other
> -|fields
> -|> need a 16-byte alignment for best performance; therefore there
> -|is nothing
> -|to
> -|> imply that any data structure not containing pointers is aligned on a
> -|> 16-byte boundary.
> -|>
> -|> The data structure being discussed in this thread does not
> -|contain actual
> -|> pointer fields since it is an externally described data structure
using
> -|> character fields to hold pointers, therefore there is no reason
> -|to assume
> -|> any particular alignment.
> -|>
> -|> The use of the ALIGN keyword does not imply changing the data
structure
> -|> itself to ANY particular byte alignment, only to adding padding
between
> -|> individual fields in the data structure to align float, signed
integer,
> -|and
> -|> unsigned integer fields for performance.
> -|>
> -|> Ken
> -|> Southern Wine and Spirits of Nevada, Inc.
> -|> Opinions expressed are my own and do not necessarily represent the
views
> -|of
> -|> my employer or anyone in their right mind.
> -|>
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