Re: Isn't this in favour of Ada??

[Marin David Condic <nobody@noplace.com>]

Yes and No. Yes, you can tie an interrupt handler to a system signal as 
if it were the same as a hardware interrupt. No, in that I'd like 
another layer of abstraction. I want to separate the system dependent 
signal from the system-independent response.

Think about it this way: Interfacing to hardware these days typically 
involves three things: Reading from some special addresses, writing to 
some special addresses and responding to some hardware interrupts. So I 
might isolate my hardware beneath a package that looks like this:

package HW_Isolator is

     Some_Interrupt : signal ; -- Not really Ada - but like an exception.

     procedure Read (blah) ;
     procedure Write (blah) ;

end HW_Isolator ;

If I have some way of connecting task entries or protected type 
procedures to "Sime_Interrupt" and have a language mechanism similar to 
exception propogation (as in "raise Some_Interrupt ;") then beneath the 
package HW_Isolator I can either a) connect Some_Interrupt directly to 
the hardware or b) connect it to a simulation of the hardware running on 
a PC. My embedded code othewrwise functions identically running on the 
real processor and running in an off-line simulation.

Presumably, having the ability to do something like "raise 
Some_Interrupt ;" anywhere in your code and have it asynchronously 
trigger execution of some other logic would be of advantage beyond 
hardware isolation, but I have not given that much thought. Perhaps it 
might be viewed as "Dangerous" as well?

MDC


Ed Falis wrote:
> 
> With GNAT, the RM mechanisms for handling interrupts are used for 
> signals  on "native" platforms, so you should be able to do something 
> like what you  want now.
> 
> - Ed

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Marin David Condic
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