C->Ada: Converting char* to unsigned long

C->Ada: Converting char* to unsigned long

[Chris Jones]

How can I convert the following to ada:

  bcopy( (char*)pHost_Info->h_addr, 
	 (char*)&Serv_Addr.sin_addr, 
	 pHost_Info->h_length );
  
where:

-- pHost_Info->h_addr is a char* to a string with length h_length,
-- Serv_Addr.sin_addr is an unsigned long

I have tried Unchecked_Conversion, but it does not work for the 
unconstrained type Interfaces.C.Char_Array.

A function which does a straight byte copy without regard to type
would be helpful, I guess...

thanks in advance.
chris jones.

cbj1329@is2.nyu.edu

Re: C->Ada: Converting char* to unsigned long

[Pascal Ledru]

As you noticed the problem comes from the fact that you cannot 
instantiate Unchecked_Conversion (or any generic) with an 
unconstrained type.

There is probably a simpler solution but the following will work:

with Text_IO;
with Interfaces.C.Strings;
use  Interfaces.C.Strings;
procedure convert is

  package Integer_IO is new Text_IO.Integer_IO(Integer);

  C : chars_ptr;
  I : Integer;

  subtype Short_String is String(1..4);
  S : String(1..4);

  function To_Integer is new Unchecked_Conversion
    ( Source => Short_String,
      Target => Integer );

begin
  C := New_String( Str => "AAAA" & ASCII.NUL ); -- char*
  S := Value( Item => C);
  Integer_IO.Put( Item => To_Integer(S), Base => 16 );
  Text_IO.New_Line;
end;