Re: question about functions (bis)

["David C. Hoos, Sr." <david.c.hoos.sr@ada95.com>]

Pascal LEJEUNE <pascal.lejeune@matra-transport.fr> wrote in message
news:8690s0$8tq$1@news.mgn.net...
> Hello everybody,
>
> Thank you for your replies !!!!
> What I want to do, is to give my user the possibility of operators
> to a type (for example C := A + B, C := A - B, C := A < B ...). This
> type is not very complex (a record of 4 bytes).
> Then, my operator is a rename of a function, for example :
> function "+" (A, B : in T) return T renames ADD;
>
> Finaly, my function ADD use a hardware component which do
> the operation with the addresses (it's an asic which needs
> to know on which variable the operation is done) :
>
> function ADD (A, B : in T) return T is
>    tmp : system.address;
> begin
>    << find the address of the result (that's my problem !!) >> and
>    put it in a local variable (tmp)
>
>    call a procedure which use directly the hardware :
>    proc (a'address, b'address, tmp);
> end ADD;
>
> So, the problem is quite simple : the type T is a "numerical" type
> on which it is normal to have operators ... but the hardware need
> to have the address of the arguments and the address of the result !!!
>
> I hope i'll find a "nice" solution (ie in Ada or C), but if it is
> impossible,
> i'll use ASM !
Why don't you declare a local variable for the result, then after the
hardware has done its job, return the value of the result to the caller,
say, as follows:

function ADD (A, B : in T) return T is
   tmp : T;
begin
   call a procedure which use directly the hardware :
   proc (a'address, b'address, tmp'address);
   return tmp;
end ADD;