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Date: Mon, 7 Sep 2015 04:39:33 -0700 (PDT)
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Subject: Addressing in Object Ada v/s GNAT (2013)  showing Vast Differences
From: Lucas Redding <lucas.redding@gmail.com>
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Xref: news.eternal-september.org comp.lang.ada:27724
Date: 2015-09-07T04:39:33-07:00
List-Id: <comp.lang.ada>

Hi

I was wondering how the addressing mechanism works in GNAT Ada? Is it so va=
stly different to Object Ada? Is there a way I can tailor the GNAT addressi=
ng mechanism to follow that of Object Ada?

I have a program that runs perfectly in Object Ada. The program relies heav=
ily on "USE AT" clauses together with 'SIZE on underlying type definition. =
This is in order to map directly and deterministically to memory with bit p=
recision. The data is independently produced so this is very important.

I have compiled the program is GNAT Ada but I am getting run time errors su=
ch as "misaligned address value". More worryingly, any data read from memor=
y that relies on the addressing mechanisms described above is incoherent.

I am interested in moving to GNAT Ada because I believe the accompanying to=
olset is much richer and therefore more productive but I am beginning to wo=
nder whether this is too onerous task?

Any help is greatly appreciated.

Lucas