Hardware Interrupts

["Carroll-Tech" <andrew@carroll-tech.net>]

Has anyone here read "Ada Concurrent Programming" by Narain Gehani?
In the book, Narain talks about address clauses.  For example:

task Interrupt_handler is
    entry DONE;
    for DONE use at 16#40#;
end Interrupt_handler;

Can an address clause be done with a procedure or function instead of a
task entry?
What about arguments?
How can I capture a return value, if there is one?

I want to call the BIOS interrupt (INT11h) to get the equipment list
word.  In my Assembly book it says that INT11h "returns" a word
containing the equipment list.  I'm assuming that a '1' at a given bit
within the word means the equipment is in the computer and '0' is not.

Here is my code so far
-------------------------------------------------------
with ada.text_io; use ada.text_io;
with system.interrupts; use system.interrupts;

procedure getequipment is
 type equiplist is array(0..15) of boolean;
 package boolean_io is new enumeration_io(boolean);
 procedure getlist(list: out equiplist);
 for getlist use at reference(16#11#);
 mylist: equiplist;

begin
 getlist(mylist);

-- for I in 0..15 loop
--  boolean_io.put(mylist(i));
-- end loop;
end getequipment;
------------------------------------------------------

When I compile this code the compiler says several things
that I do not know how to fix.

getequipment.adb:2:12: warning: "system.interrupts" is an internal GNAT unit
getequipment.adb:2:12: warning: use of this unit is non-portable and
version-dependent
getequipment.adb:7:09: missing body for "getlist"
getequipment.adb:8:13: address clause can only be given for imported
subprogram

Any ideas?

Maybe there is an easier way to call INT11h from Ada?
I looked into System.Machine_Code and the ASM procedure but that seems
pretty
complex (per GNAT reference manual explanation).