Re: Comparing Access Types

[Jere <jhb.chat@gmail.com>]

On Friday, November 10, 2017 at 3:35:10 AM UTC-5, Dmitry A. Kazakov wrote:
> On 09/11/2017 23:38, Robert A Duff wrote:
> > "Dmitry A. Kazakov" writes:
> > 
> >> ...Actually even equality cannot
> >> be for segmented memory but it felt good enough.
> > 
> > ?
> > 
> > "=" returns True if two access values designate the same object,
> > which is a well defined concept, and has nothing to do with
> > segmented memory.  And it's easy to implement, whether memory
> > is segmented or not.
> 
> You could have two segments mapped to the same physical memory. Then you 
> may have two unequal segmented addresses pointing to the same physical 
> memory unit and so "=" will lie.
> 
> -- 
> Regards,
> Dmitry A. Kazakov
> http://www.dmitry-kazakov.de

I know that a lot of the embedded C compilers that we use overcome
this issue by encoding unique segment information into their pointers.
So a pointer isn't just a physical address, but something more that
expresses a unique location based on physical memory location + whatever
other information is available.  I don't know enough about Ada compilers,
but my expectation is that they could also solve that problem (maybe
the same way or maybe in a better way).