From: "John R. Strohm" <strohm@airmail.net>
Subject: Re: Help with Copying Shared Memory to Local
Date: Fri, 24 May 2002 13:43:09 -0700
Date: 2002-05-24T13:43:09-07:00 [thread overview]
Message-ID: <EE1B58C60CD7D9ED.3DE0D594451AD094.92104DC9322C357A@lp.airnews.net> (raw)
In-Reply-To: ulma9mqnj.fsf@gsfc.nasa.gov
type x is record
csr: byte;
dr: byte;
end record;
for x use record at mod 2;
for x'size use 16;
Or something of that nature.
Admittedly, it has been a number of years since I last looked at Ada rep
specs. The thing I remember most painfully was laying out the registers for
a Signetics 2681 DUART, and then writing a reusable device driver as a set
of four generics.
"Stephen Leake" <stephen.a.leake.1@gsfc.nasa.gov> wrote in message
news:ulma9mqnj.fsf@gsfc.nasa.gov...
> "John R. Strohm" <strohm@airmail.net> writes:
>
> > Ada representation specifications provide a clean way to
> > tell the compiler what kind of access to use,
>
> This is _not_ what rep spec say. They say how to lay out the bits in
> memory, not how to access them.
>
> > and most compilers were good about following the programmer's
> > wishes.
>
> Some compilers do "what you want", but there is _no_ guarrantee in the
> language for this.
>
> If you need a 16 bit access, use assembly code. Wrap it up in a
> low-level Ada subprogram, to make it easy to use.
>
> Yes, it feels inefficient and inelegant, but it is the best approach.
>
> --
> -- Stephe
next prev parent reply other threads:[~2002-05-24 20:43 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2002-05-23 13:50 Help with Copying Shared Memory to Local John Cupak
2002-05-23 20:32 ` Jeffrey Carter
2002-05-23 21:18 ` John Cupak
2002-05-24 1:37 ` Randy Brukardt
2002-05-24 2:08 ` Jeffrey Carter
2002-05-24 17:05 ` John R. Strohm
2002-05-24 16:55 ` Stephen Leake
2002-05-24 20:43 ` John R. Strohm [this message]
2002-05-24 19:49 ` Pat Rogers
2002-05-24 23:23 ` martin.m.dowie
2002-05-24 20:54 ` Stephen Leake
2002-05-24 19:41 ` Jeffrey Carter
2002-05-26 0:55 ` John Cupak
2002-05-28 17:52 ` John Cupak
2002-05-25 11:23 ` Robert Dewar
2002-05-26 4:48 ` Jeffrey Carter
-- strict thread matches above, loose matches on Subject: below --
2002-05-24 14:22 Beard, Frank [Contractor]
2002-05-24 19:30 ` Jeffrey Carter
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