program spectrumJoystick;

target = spectrum;

*      = $8000;

uses
  zxspectrum_graphics,spectrum_joy,spectrum_irq;

type
  TPlayer = record
    x       : Byte;
    y       : Byte;
    nx      : Byte;
    ny      : Byte;
  end;

var
  player : TPlayer;

procedure vbInterrupt;
begin
end;

procedure player_draw;
begin
  charAt_bmpfont(player.y,player.x,ord('@'),white,black,ROM_CHARSET);
end;

procedure erase;
begin
  charAt_bmpfont(player.y,player.x,ord(' '),white,black,ROM_CHARSET);
end;

procedure player_drawTail;
begin
  charAt_bmpfont(player.y,player.x,ord('.'),yellow,black,ROM_CHARSET);
end;

const
  FRAME_COUNT = 6;

var
  frame : Byte;

begin
  ROM_CLS();
  BORDER(cyan);

  setupInterrupt(@vbInterrupt);

  player.x  := SCREEN_WIDTH  / 2;
  player.y  := SCREEN_HEIGHT / 2;
  player.nx := player.x;
  player.ny := player.y;

  while true do begin
    waitFor_vblank();

    read_Kempston();

    Inc(frame);

    // slowdown movement
    if frame >= FRAME_COUNT then begin
      frame := 0;
      player_drawTail();

      if (joystick.dx = JOY_LEFT) then begin
        player.nx      := player.x - 1;
        if (player.nx and 128) then player.nx := 0;
      end
      else
      if (joystick.dx = JOY_RIGHT)  then begin
        player.nx      := player.x + 1;
        if player.nx >= SCREEN_WIDTH then player.nx := SCREEN_WIDTH - 1;
      end;

      if (joystick.dy = JOY_UP) then begin
        player.ny      := player.y - 1;
        if (player.ny and 128) then player.ny := 0;
      end
      else
      if (joystick.dy = JOY_DOWN)  then begin
        player.ny      := player.y + 1;
        if player.ny >= SCREEN_HEIGHT then player.ny := SCREEN_HEIGHT - 1;
      end;

      player.x := player.nx;
      player.y := player.ny;
      player_draw();
    end;
  end;
end.