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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 size = 2;
if (ioport("DSW")->read() & 0x40)
{
size = 4;
}
for (int ybit = 0; ybit < 2; ybit++)
{
if (y + ybit < 0 || y + ybit >= VERT_RES * VERT_CHR)
return;
for (int xbit = 0; xbit < size; xbit++)
{
if (x + xbit < 0 || x + xbit >= HORZ_RES * HORZ_CHR)
continue;
bitmap.pix(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;
}
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