jeste k radio karte

[Michal Leinweber]

Moje packalska unitka predelana z ceckovyho zdrojaku.

			McLEI

unit Card;
interface

procedure CardOff;
procedure VolumeDown;
procedure VolumeUp;
procedure Tune(freq:real);
procedure CardMute(mute:boolean);
function IsTuned:boolean;

implementation
uses Crt;


const
  RadioBase = $20C;

function read_card(sub_port:integer):byte;
{  /* reads a byte in from the card */ }
begin
  read_card := port[RadioBase+sub_port];
end;

procedure write_card(sub_port:integer; value:byte);
{ /* writes a byte to the card */ }
begin
   port[RadioBase+sub_port]:=value;
end;

procedure CardOff;
{ /* switch card off */ }
begin
   write_card(0,$00);
   write_card(0,$00);
end;

procedure VolumeDown;
{  /* vol down a notch */ }
begin
   write_card(0,$48);
   delay(100);
   write_card(0,$c8);
end;

procedure VolumeUp;
{  /* vol up a notch */ }
begin
   write_card(0,$88);
   delay(100);
   write_card(0,$c8);
end;

procedure Tune(freq:real);
{  /* tunes the radio to the desired frequency */ }
var
{   unsigned long int bits;} bits:longint;
{   int i,mask;}  i,mask:longint;
begin
{  write('Tune ', Freq:6:3);}

   bits:=round((freq*40)+10486188);
{   /* yes, i know. now where does THAT come from?
    * working out that bits=(freq*multiplier)+base
    * was hard, and working out the base and multiplier
    * was tricky. */}
   mask:=1;
   for i:=0 to 23 do begin
{     Inc(I);}
     if bits and mask = 0 then begin
	   {/* 0 bit */}
	   write_card(0,$1);
	   write_card(0,$1);
	   write_card(0,$3);
	   write_card(0,$3);
     end
     else begin
	{  /* bit is 1 */ }
	   write_card(0,$5);
	   write_card(0,$5);
	   write_card(0,$7);
	   write_card(0,$7);
     end;
     Mask:=mask*2;
   end;
{   /* termination sequence? */}
   write_card(0,$0);
   delay(10);
   write_card(0,$c8);
end;

{/* CardMute basis from Frans Brinkmann adapted to card.c */}

procedure CardMute(mute:boolean);
begin
  if mute then begin
    {/* shut it up */}
    write_card(0,$0);
    write_card(0,$0);
  end
  else begin
  { /* turn sound on */ }
    write_card(0,$0);
    write_card(0,$c8);
  end;
end;

{/* IsTuned from Frans Brinkmann adapted to card.c */}

function IsTuned:boolean;
var
  x:integer;
begin
  x:=0;
{
/* test tuning */
/*
	DO NOT CHANGE THE TIMING !?!?!?

	Scanning seems to be pretty unreliable, or at least using
	the one card I've got. A shorter wait will miss lots of valid
	stations, longer ones will make it find lots of noisy signals.
        Should anyone ever find out how it is supposed to work please
	let me know. For absolutely no reason that I can see it also seems
        to work slightly better if the frequencies used are multiples
        of .05, but that might just be coincidence
*/}
      write_card(0, $f8);

      delay(200); {             /* any faster and it won't work? */}
      x := read_card(0);
{      /* x = inb(RadioBase); */}
      delay(25);              { /* set from 10000 to 25000. is this better?
*/}
      write_card(0,$e8);

{      /* if x == ff not tuned, if x == fd then tuned */}

      if (( x and 255) <> $ff) then IsTuned := true
      else IsTuned := false;
end;

end.