/***************************************************************************
Atari Blasteroids hardware
****************************************************************************/
#include "emu.h"
#include "machine/atarigen.h"
#include "video/atarimo.h"
#include "includes/blstroid.h"
/*************************************
*
* Tilemap callbacks
*
*************************************/
static TILE_GET_INFO( get_playfield_tile_info )
{
blstroid_state *state = machine.driver_data<blstroid_state>();
UINT16 data = state->m_playfield[tile_index];
int code = data & 0x1fff;
int color = (data >> 13) & 0x07;
SET_TILE_INFO(0, code, color, 0);
}
/*************************************
*
* Video system start
*
*************************************/
VIDEO_START( blstroid )
{
static const atarimo_desc modesc =
{
1, /* index to which gfx system */
1, /* number of motion object banks */
1, /* are the entries linked? */
0, /* are the entries split? */
0, /* render in reverse order? */
0, /* render in swapped X/Y order? */
0, /* does the neighbor bit affect the next object? */
0, /* pixels per SLIP entry (0 for no-slip) */
0, /* pixel offset for SLIPs */
0, /* maximum number of links to visit/scanline (0=all) */
0x000, /* base palette entry */
0x100, /* maximum number of colors */
0, /* transparent pen index */
{{ 0,0,0x0ff8,0 }}, /* mask for the link */
{{ 0 }}, /* mask for the graphics bank */
{{ 0,0x3fff,0,0 }}, /* mask for the code index */
{{ 0 }}, /* mask for the upper code index */
{{ 0,0,0,0x000f }}, /* mask for the color */
{{ 0,0,0,0xffc0 }}, /* mask for the X position */
{{ 0xff80,0,0,0 }}, /* mask for the Y position */
{{ 0 }}, /* mask for the width, in tiles*/
{{ 0x000f,0,0,0 }}, /* mask for the height, in tiles */
{{ 0,0x8000,0,0 }}, /* mask for the horizontal flip */
{{ 0,0x4000,0,0 }}, /* mask for the vertical flip */
{{ 0 }}, /* mask for the priority */
{{ 0 }}, /* mask for the neighbor */
{{ 0 }}, /* mask for absolute coordinates */
{{ 0 }}, /* mask for the special value */
0, /* resulting value to indicate "special" */
0 /* callback routine for special entries */
};
blstroid_state *state = machine.driver_data<blstroid_state>();
/* initialize the playfield */
state->m_playfield_tilemap = tilemap_create(machine, get_playfield_tile_info, tilemap_scan_rows, 16,8, 64,64);
/* initialize the motion objects */
atarimo_init(machine, 0, &modesc);
}
/*************************************
*
* Periodic scanline updater
*
*************************************/
static TIMER_CALLBACK( irq_off )
{
address_space *space = machine.device("maincpu")->memory().space(AS_PROGRAM);
/* clear the interrupt */
atarigen_scanline_int_ack_w(space, 0, 0, 0xffff);
}
static TIMER_CALLBACK( irq_on )
{
/* generate the interrupt */
atarigen_scanline_int_gen(machine.device("maincpu"));
atarigen_update_interrupts(machine);
}
void blstroid_scanline_update(screen_device &screen, int scanline)
{
blstroid_state *state = screen.machine().driver_data<blstroid_state>();
int offset = (scanline / 8) * 64 + 40;
/* check for interrupts */
if (offset < 0x1000)
if (state->m_playfield[offset] & 0x8000)
{
int width, vpos;
attotime period_on;
attotime period_off;
/* FIXME: - the only thing this IRQ does it tweak the starting MO link */
/* unfortunately, it does it too early for the given MOs! */
/* perhaps it is not actually hooked up on the real PCB... */
return;
/* set a timer to turn the interrupt on at HBLANK of the 7th scanline */
/* and another to turn it off one scanline later */
width = screen.width();
vpos = screen.vpos();
period_on = screen.time_until_pos(vpos + 7, width * 0.9);
period_off = screen.time_until_pos(vpos + 8, width * 0.9);
screen.machine().scheduler().timer_set(period_on, FUNC(irq_on));
screen.machine().scheduler().timer_set(period_off, FUNC(irq_off));
}
}
/*************************************
*
* Main refresh
*
*************************************/
SCREEN_UPDATE( blstroid )
{
blstroid_state *state = screen->machine().driver_data<blstroid_state>();
atarimo_rect_list rectlist;
bitmap_t *mobitmap;
int x, y, r;
/* draw the playfield */
tilemap_draw(bitmap, cliprect, state->m_playfield_tilemap, 0, 0);
/* draw and merge the MO */
mobitmap = atarimo_render(0, cliprect, &rectlist);
for (r = 0; r < rectlist.numrects; r++, rectlist.rect++)
for (y = rectlist.rect->min_y; y <= rectlist.rect->max_y; y++)
{
UINT16 *mo = (UINT16 *)mobitmap->base + mobitmap->rowpixels * y;
UINT16 *pf = (UINT16 *)bitmap->base + bitmap->rowpixels * y;
for (x = rectlist.rect->min_x; x <= rectlist.rect->max_x; x++)
if (mo[x])
{
/* verified via schematics
priority address = HPPPMMMM
*/
int priaddr = ((pf[x] & 8) << 4) | (pf[x] & 0x70) | ((mo[x] & 0xf0) >> 4);
if (state->m_priorityram[priaddr] & 1)
pf[x] = mo[x];
/* erase behind ourselves */
mo[x] = 0;
}
}
return 0;
}