text: /*************************************************************/
  /*                                                           */
  /* Lazer Command video handler                               */
  /*                                                           */
  /*************************************************************/
  
  #include "emu.h"
  #include "includes/lazercmd.h"
  
  /* scale a markers vertical position */
  /* the following table shows how the markers */
  /* vertical position worked in hardware  */
  /*  marker_y  lines    marker_y  lines   */
  /*     0      0 + 1       8      10 + 11 */
  /*     1      2 + 3       9      12 + 13 */
  /*     2      4 + 5      10      14 + 15 */
  /*     3      6 + 7      11      16 + 17 */
  /*     4      8 + 9      12      18 + 19 */
  static int vert_scale(int data)
  {
  	return ((data & 0x07) << 1) + ((data & 0xf8) >> 3) * VERT_CHR;
  }
  
  /* plot a bitmap marker */
  /* hardware has 2 marker sizes 2x2 and 4x2 selected by jumper */
  /* meadows lanes normaly use 2x2 pixels and lazer command uses either */
  static void plot_pattern( running_machine &machine, bitmap_t *bitmap, int x, int y )
  {
  	int xbit, ybit, size;
  
  	size = 2;
  	if (input_port_read(machine, "DSW") & 0x40)
  	{
  		size = 4;
  	}
  
  	for (ybit = 0; ybit < 2; ybit++)
  	{
  	    if (y + ybit < 0 || y + ybit >= VERT_RES * VERT_CHR)
  		    return;
  
  	    for (xbit = 0; xbit < size; xbit++)
  		{
  			if (x + xbit < 0 || x + xbit >= HORZ_RES * HORZ_CHR)
  				continue;
  
  			*BITMAP_ADDR16(bitmap, y + ybit, x + xbit) = 4;
  		}
  	}
  }
  
  
  SCREEN_UPDATE( lazercmd )
  {
  	lazercmd_state *state = screen->machine().driver_data<lazercmd_state>();
  	int i, x, y;
  
  	int video_inverted = input_port_read(screen->machine(), "DSW") & 0x20;
  
  	/* The first row of characters are invisible */
  	for (i = 0; i < (VERT_RES - 1) * HORZ_RES; i++)
  	{
  		int sx, sy;
  
  		sx = i % HORZ_RES;
  		sy = i / HORZ_RES;
  
  		sx *= HORZ_CHR;
  		sy *= VERT_CHR;
  
  		drawgfx_opaque(bitmap, cliprect,screen->machine().gfx[0],
  				state->m_videoram[i], video_inverted ? 1 : 0,
  				0,0,
  				sx,sy);
  	}
  
  	x = state->m_marker_x - 1;             /* normal video lags marker by 1 pixel */
  	y = vert_scale(state->m_marker_y) - VERT_CHR; /* first line used as scratch pad */
  	plot_pattern(screen->machine(), bitmap, x, y);
  
  	return 0;
  }
  