Re: updating a hardware cursor with assembly and ada

[Adam Beneschan <adam@irvine.com>]

On Mar 6, 9:51 am, cl1 <charles.w.lamb...@gmail.com> wrote:
> On Mar 6, 11:26 am, Georg Bauhaus <rm.tsoh-plus.nicif-
>
> bauh...@maps.futureapps.de> wrote:
> > cl1 schrieb:
>
> > > unsigned char outportb (unsigned short _port, unsigned char _data)
> > > {
> > >  __asm__ __volatile__ ("outb %1, %0" : : "dN" (_port), "a" (_data));
> > > }
> > > ---------------------------------------------------------------------------­--
> > >   procedure Update_Cursor (Console : Video_Console) is
> > >      procedure OutportB (Port : Natural; Data : Natural);
>
> > Does type Natural match C type unsigned short on your system?
>
> If it didn't, what problem would this pose?

Assuming Natural is 32 bits (I don't really know): If the code
generated for your Ada program thinks it's passing two 32-bit integers
as parameters, but the runtime code is expecting a 16-bit integer and
an 8-bit integer as parameters, the runtime code may not use correct
values for the parameters.


> > (Just a guess.) Maybe Interfaces.Unsigned_N is better choice.
>
> I have no runtime (this is os development code). I don't know if i can
> use the Interfaces packages in gnat with out it. I tried to implement
> Unsigned_16 with out the operations and the compiler complained about
> not having primitive operations defined on the part where i was doing
> Data : Unsigned_16 := Console.Column * 80 + Console.Row; even when
> Column and Row were of type Unsigned_16;

The operations "*" and "+" aren't automatically available, unless you
do something to make them visible.  Try "use type
Interfaces.Unsigned_16;".

                               -- Adam