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// license:GPL-2.0+
// copyright-holders:Juergen Buchmueller
/*************************************************************/
/*                                                           */
/* 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 */
int lazercmd_state::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 */
void lazercmd_state::plot_pattern( bitmap_ind16 &bitmap, int x, int y )
{
	int xbit, ybit, size;

	size = 2;
	if (ioport("DSW")->read() & 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.pix16(y + ybit, x + xbit) = 4;
		}
	}
}


uint32_t lazercmd_state::screen_update_lazercmd(screen_device &screen, bitmap_ind16 &bitmap, const rectangle &cliprect)
{
	int i, x, y;

	int video_inverted = (ioport("DSW")->read() ^ m_attract) & 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;

		m_gfxdecode->gfx(0)->opaque(bitmap,cliprect,
				m_videoram[i], video_inverted ? 1 : 0,
				0,0,
				sx,sy);
	}

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

	return 0;
}