Re: Ada Address = C pointer ?

["M. A. Alves" <maa@liacc.up.pt>]

On Mon, 29 Oct 2001, Matthew Heaney wrote:
> "M. A. Alves" <maa@liacc.up.pt> wrote in message
> news:mailman.1004357020.21840.comp.lang.ada@ada.eu.org...
> > You mean use Address_To_Access conversion?  Because what I have is C
> > pointers I need to interface with.  I am using Chars_Ptr because it has a
> > Null_Ptr value and I need to test for, and pass, NULL.  (And in C char *
> > is assuredly able to point to anything.)  But I am indeed considering
> > using Address et al., and Address to Access conversion.
>
> . . .
>
> I do NOT think you need to use System.Address and Addr_To_Acc_Conv.  The
> types declared in C.Strings should be adequate.

I am in fact using Address and Access_To_Address_Conversions(*) because I
simply did not find out how to do the trick otherwise.  For example, the C
function is returning an array of unsigned long.  I want to access that
array without copying it.  How can you do that with Interfaces.C.Strings
or even Interfaces.C.Pointers ?

Also, I did not found the equivalence Null_Ptr = NULL stated in the RM.

> That being said, I would be very surprised if System.Address had a
> different representation from char* or void*.

Yes, and for now my implementation is bound to that assumption.
_____
(*) I am using a technique similar to the one referenced as 2c in
"Accessing Memory as a String" by Robert Dewar, available at
adapower.com/lang/accessmem.html .

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