Re: Embedded Ada Development Tools

[gab@rational.com (Greg Bek)]

John Kern <jkern3@NOSPAM.visteon.com> wrote in message news:<3CFE29BB.A7D22E77@NOSPAM.visteon.com>...
> 
> One of these days, I'm going to buy my son the Lego Mindstorms kit and
> get that Ada compiler working.

The best way to do this is to start with Barry Fagin's ada2nqc program.
It allows you to write pure Ada code and then translate it into NQC
for compilation and download to the RCX.

I took Barry's code and added tasking and a couple of other things
to it, although I think Barry has since done it as well.

There is some slight mismatch between Ada tasking semantics and
the Lego RCX tasking, but it doesn't stop you writing pure Ada
code.  The code might not work if ported to another target, but
that isn't a real problem in this domain.

Here is some sample code in Ada:
with Lego;
use Lego;
procedure scanbot is
  Angle : constant Sensor_Port := Sensor_1;
  Eye : constant Sensor_Port := Sensor_3;
  
  Left : constant Output_Port := Output_A;
  Head : constant Output_Port := Output_B;
  Right : constant Output_Port := Output_C;
  
  Slop : constant Integer := 2;
  
  Center : constant Integer := 53;
  Sweep : constant Integer := 48;
  
  Align_Time : constant Integer := 300; -- 3 seconds
  Turn_Time : constant Integer := 50; -- 1/2 second
  
  Threshold : constant Integer := 65;
  
  procedure Align is
     Current : Integer;
  begin
    Output_Reverse (Head);
    Clear_Sensor(Angle);
    Current := Get_Sensor_Value(Angle);
    Output_On(Head);
    Wait (100);
    while ( Current /= Get_Sensor_Value (Angle )) loop
       Current := Get_Sensor_Value(Angle);
       Wait (200);
    end loop;
   
    Output_Off(Head);
    Output_Forward (Head);
    Clear_Sensor(Angle);
  end Align;
  
  task Steer is
     entry Start;
     entry Stop;
  end Steer;
  
  task body Steer is
  begin
     accept Start;
     While (True) loop
      if (Eye > Threshold) then
         Output_Off(Head);
         Play_Sound(Click);
         if (Angle < Center - Slop) then
            Output_Reverse(Left);
            Wait(Turn_Time);
            Output_Forward(Left);
         else if (Angle > Center + Slop ) then
               Output_Reverse(Right);
               Wait(Turn_Time);
               Output_Forward(Right);
            end if;
         end if;
         Output_On(Head);

      end if;     
     end loop;
  end Steer;

begin
  Config_Sensor(Eye, Config_Light);
  Config_Sensor(Angle, Config_Rotation);

  Align;

  Output_on ( Left + Right + Head );

  Steer.Start;

  while (True) loop
    if (Angle < (Center - Sweep)) then
      Output_Forward (Head);
    else
       if (Angle > (Center + Sweep)) then
          Output_Reverse (Head);
       end if;
    end if;   
  end loop;  

end;