Re: Ada Microkernel?

[James Rogers <jimmaureenrogers@worldnet.att.net>]

"B. Douglas Hilton" wrote:
> 
> Ok, here is the oskit "hello" kernel. Any ideas how to convert this
> to Ada?
> 
> #include <stdio.h>
> #include <oskit/clientos.h>
> #include <oskit/startup.h>
> #include <oskit/version.h>
> 
> int main()
> {
> #ifndef KNIT
>         oskit_clientos_init();
> #endif
> #ifdef  GPROF
>         start_fs_bmod();
>         start_gprof();
> #endif
>         oskit_print_version();
>         printf("Hello, World\n");
>         return 0;
> }
> 

The first rule to learn is that Ada should be written as Ada and
C should be written as C. 

Clearly, any standard Ada version would not use a preprocessor.

The C preprocessor conditionals provide for conditional compilation
of the C sources. The Ada way to achieve the same goal is to
provide several versions of the entry point procedure for the 
program, each one specifying its own set of dependencies.

Each of the include files in the C version will require a
corresponding Ada package. The Ada package corresponding to stdio.h
is clearly Ada.Text_Io. Each of the other included files must
be rewritten in Ada.

One version of the Ada entry point procedure might look like the
following:

with Oskit.ClientOs;
with OsKit.Startup;
with OsKit.Version;
with Ada.Text_Io;

procedure HelloKernel is
begin
   OsKit.ClientOs.Init;
   OsKit.Startup.FsBmod;
   OsKit.Startup.Gprof;
   OsKit.Version.Print;
   Ada.Text_Io.Put_Line("Hello World!");
end HelloKernel;

Jim Rogers
Colorado Springs, Colorado USA