Re: Ada is almost useless in embedded systems

[john@assen.demon.co.uk (John McCabe)]

dewar@cs.nyu.edu (Robert Dewar) wrote:

>John McCabe said

>"If you check the detail of pragma shared, I think you'll find this
>does not provide the same facilities as the C 'volatile' attribute. I
>have checked this according to my compiler manual, so I do know what
>I'm talking about here.

>Also, as I've mentioned elsewhere, I know nothing about Ada 95, all my
>comments are purely Ada 83."

>This is wrong, pragma shared corresponds to pragma Atomic in Ada 95,
>not to pragma Volatile (and the volatile keyword in C).

I'm sorry Robert but I don't see understand why you are saying this is
wrong. I am not suggesting here that there is a correspondence between
shared and anything to do with Ada 95.

>Volatile does not require atomic access and can be applied to anything.
>Atomic (Shared) can only be applied to objects for which atomic access
>can be guaranteed, which is likely to be very restrictive.

>There is no equivalent of pragma Volatile in Ada 83.

I do appreciate the response though as myself and Jon have also been
discussing this using email and I was going to attempt to email you
for an explanation of pragma volatile. I had a look at John Barnes'
book Programming in Ada 95 yesterday and it seems to skimp over it.

Additional detail would be appreciated on this one.


Best Regards
John McCabe <john@assen.demon.co.uk>