Tracking segfaults

[imcold]

You're getting errors due to changing the Chunk.Data in your keyboard handling code. The your keyboard handler is running in another context/thread (read the doc carefully: http://allegro-pas.sourceforge.net/d...install_int_ex). What does this mean? The data modified in the handler can change at any moment, independently of your main loop routine - if it changes when you're in your Draw routine, all hell's gonna break loose due to invalid pointers etc.
The solution is to just set a flag to signal that a world refresh is needed, and check it in the main loop (and there should be a lock around the flag, to do things 100% properly; but you can probably get away without it in this case).

var
    update_chunks: boolean;

  procedure RegenerateChunk;
  begin
    update_chunks := false;
    Chunk.Data:=WorldGenerator.GenerateChunkData(chunkx,0,18);
    Inc(chunkx);
    al_clear_to_color(perlin,al_makecol(255,0,255));
    for x:=0 to 100-1 do
    begin
      for y:=0 to 100-1 do
      begin
        al_putpixel(perlin,x,y,generate_pixel(x,y));
      end;
    end;
  end;

  procedure update_keyboard();
  begin
      Dec(lasted);
      dec(chunklasted);
      if (al_keyboard_needs_poll) then al_poll_keyboard;
      if ((al_key[AL_KEY_P]<>0) and (lasted<=0)) then begin pause:=not pause; lasted:=pausedelay; end;
      if not pause then begin

        if ((al_key[AL_KEY_SPACE]<>0) and (chunklasted<=0)) then
        begin
          update_chunks := true;
          chunklasted:=pausedelay;
        end;
      end;
  end;

main routine:

      repeat
        draw;
        if update_chunks then
            RegenerateChunk;
      until (al_key[AL_KEY_Q]<>0) or quit;