Hardware Interrupts

Hardware Interrupts

[Carroll-Tech]

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).

system calls, was Re: Hardware Interrupts

[tmoran]

> task Interrupt_handler is
> ...
> I want to call the BIOS interrupt (INT11h) to get the equipment list
  The task stuff is about *handling* interrupts, but you want to *call*
something via a software interrupt.  Compiler vendors normally supply
packages to do such system dependent things - presumably your copy of
Gnat does too.
  If not, you will need to find such a package (or find one in C and
interface to it) or else you'll have to use "machine code insertions"
and code in assembly to set up the calling sequence, issue the interrupt,
and retrieve the results.
  BTW, what machine has a BIOS INT11h call?

Re: Hardware Interrupts

[sk]

andrew@carroll-tech.net:

 > 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

I don't know any answers to your questions. What I do
remember about any assembly calls to BIOS interrupts
is that you have to set up the registers with parameters
etc.

You are using GNAT from your examples. Which version
and platform ?

If it is an Intel compiler running in "protected" mode,
that is 32-bit address space etc, the physical address
"16#11# does not corespond to the interrupt 11. Once
32-bit protected mode is entered, the Interrupts are
gated and are typically not at the booting 0 .. 255
address space of an Intel 386 processor boot prior to
entering protected mode.

Another thing to note is that, I believe, the BIOS
is not accessible as regular memory once Intel 32-bit
protected mode is established (I could be wrong on this :-)

If you are still determined to go into never-never land,
you need to look at Ada's machine code insertions. The
code you posted looks potentially fatal to your machine.

So, beyond Gnat telling you the code is non-portable, I
would say it is also, at the least, not what you are
looking for, at worst calling "format disk" which is
a BIOS routine of almost 20 years ago before the
current IDE standards were established.

Sorry, not much help, but I am hoping that you don't
trash your system by being determined to call a
possible inaccessible BIOS.

Simon :-)

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