/*************************************************************/
/*                                                           */
/* Lazer Command video handler                               */
/*                                                           */
/*************************************************************/

#include "driver.h"
#include "includes/lazercmd.h"

int marker_x, marker_y;


/* 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, mame_bitmap *bitmap, int x, int y)
{
	int xbit, ybit, size;

    size = 2;
	if (input_port_2_r(0) & 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;
		}
	}
}


VIDEO_UPDATE( lazercmd )
{
	int i,x,y;

	int video_inverted = input_port_2_r(0) & 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(bitmap, machine->gfx[0],
				videoram[i], video_inverted ? 1 : 0,
				0,0,
				sx,sy,
				&machine->screen[0].visarea,TRANSPARENCY_NONE,0);
	}

	x = marker_x - 1;             /* normal video lags marker by 1 pixel */
	y = vert_scale(marker_y) - VERT_CHR; /* first line used as scratch pad */
	plot_pattern(machine, bitmap,x,y);

	return 0;
}
