Re: How do I write directly to a memory address?

[Shark8 <onewingedshark@gmail.com>]

On Feb 8, 5:13 pm, "Randy Brukardt" <ra...@rrsoftware.com> wrote:
> "Shark8" <onewingedsh...@gmail.com> wrote in message
>
> news:ee766e88-e4c4-4278-8b05-fd0dc9aa3fdb@k17g2000pre.googlegroups.com...
>
> >> How do you test the third bit of a byte in Ada?
>
> >One Way, assuming a 1..8 numbering for an 8-bit byte:
>
> Presuming I *wasn't* interviewing for a job, would be to point out that that
> is the wrong question. The question is typically something like testing the
> ready bit in a device. And the solution to that in Ada is to map the device
> to an appropriate record type, and then read that proper component. For
> instance:
>
>    type Dev_Status is
>       Read_Ready : Boolean; -- Bit 3.
>       Write_Ready : Boolean;
>       ...
>    end record;
>    for Dev_Status use record
>       Read_Ready at 0 range 3 .. 3; -- Bit 3.
>       Write_Ready at 0 range 4 .. 4;
>       ...
>    end record;
>
>    My_Dev_Status : Dev_Status
>       with Address => <something appropriate>;
>
>     if My_Dev_Status.Read_Ready then -- Testing bit 3.
>
> QED. :-)
>
>                               Randy.

That is a far more elegant & practical solution, IMO.

The problem really comes into play with the question
"How do you set the third bit?" because there is no
such context (a device in your example) with which
to base your answer, and so you must give an
answer somewhat tangential to what the actual
practical problem may be. {i.e. it 'works.'}