(*****************************************************************************
 *                      SAMPLE3.C : COUNTER/TIMER                            *
 *****************************************************************************)

program sample3;
uses
   crt,cppdelay;

const
   DEFAULT_ADDRESS='300';
   COUNTER_OFFSET=$0C;

procedure CtrMode(addr : word; cntr, mode:byte);
var
   ctrl:byte;
begin
   ctrl := (cntr shl 6) or $30 or (mode shl 1);
   port[addr+3] := ctrl;
end;

procedure CtrLoad(addr : word; c,val:word);
begin
    port[addr+c] := lo(val);
    port[addr+c] := hi(val);
end;

function CtrRead(addr : word; c : integer) : word;
var
   temp : word;
   data:word;
begin
{   port[addr+3] := c shl 6;
}   temp := port[addr+c];
   data := temp + (port[addr+c] shl 8);
   CtrRead:=data;
end;

function AskForBaseAddress(OldOne : String) : Word;
  const
     Msg : string[4] = '0';
  var
     NewOne, Success, Dummy, Error : Word;
     AddrInputPosX, AddrInputPosY : Word;
  begin

     WriteLn('Please enter the Base Address (0000-FFFF) for your card (in hex)');
     WriteLn('or press ENTER for ', OldOne, '.  ');
     Write('>');
     AddrInputPosX := WhereX; AddrInputPosY := WhereY;
     Success := 0;
     repeat
        GotoXY(AddrInputPosX, AddrInputPosY);
        ClrEol;
        Readln(Msg);
        Val('$' + Msg, NewOne, Error);
        if (error=0) then begin
           Success := 1;
           Dummy := NewOne;
        end else if (Msg = '') then begin
           GotoXY(AddrInputPosX, AddrInputPosY);
           WriteLn(OldOne);
           Msg := OldOne;
           Success := 1;
           Val('$' + Msg, Dummy, Error);
        end;
     until (Success = 1);
     AskForBaseAddress := Dummy;
  end;

var
  base:integer;
  temp, control : word;
begin

   ClrScr;
   WriteLn('Sample 3');
   WriteLn;
   WriteLn('This sample loads all three counters and continuously displays');
   WriteLn('the values that are currently in them.');
   WriteLn;

   base:= AskForBaseAddress( DEFAULT_ADDRESS);

   CtrMode( base+COUNTER_OFFSET, 0, 2);
   CtrMode( base+COUNTER_OFFSET, 1, 2);
   CtrMode( base+COUNTER_OFFSET, 2, 2);

   CtrLoad( base+COUNTER_OFFSET, 0, 100);
   CtrLoad( base+COUNTER_OFFSET, 1, 1000);
   CtrLoad( base+COUNTER_OFFSET, 2, 10000);

   clrscr;
   gotoxy(1, 15);
   writeln('The counters will count down for each negative pulse on their inputs.');

   writeln('Press a key to exit...');

   while( not keypressed) do
   begin
      gotoxy( 1,4);
      writeln('decrementing between 100 and 0');
      writeln('counter 0 = ', CtrRead( base+COUNTER_OFFSET, 0));

      gotoxy( 1,7);
      writeln('decrementing between 1000 and 0');
      writeln('counter 1 = ', CtrRead( base+COUNTER_OFFSET, 1));

      gotoxy( 1,10);
      writeln('decrementing between 10000 and 0');
      writeln('counter 2 = ', CtrRead( base+COUNTER_OFFSET, 2));

      cdelay(250);
   end;
   GotoXY(1, 20);
end.