/***************************************************************************
video.c
Functions to emulate the video hardware of the machine.
***************************************************************************/
#include "emu.h"
#include "includes/gng.h"
/***************************************************************************
Callbacks for the TileMap code
***************************************************************************/
static TILE_GET_INFO( get_fg_tile_info )
{
gng_state *state = machine.driver_data<gng_state>();
UINT8 attr = state->m_fgvideoram[tile_index + 0x400];
SET_TILE_INFO(
0,
state->m_fgvideoram[tile_index] + ((attr & 0xc0) << 2),
attr & 0x0f,
TILE_FLIPYX((attr & 0x30) >> 4));
}
static TILE_GET_INFO( get_bg_tile_info )
{
gng_state *state = machine.driver_data<gng_state>();
UINT8 attr = state->m_bgvideoram[tile_index + 0x400];
SET_TILE_INFO(
1,
state->m_bgvideoram[tile_index] + ((attr & 0xc0) << 2),
attr & 0x07,
TILE_FLIPYX((attr & 0x30) >> 4));
tileinfo->group = (attr & 0x08) >> 3;
}
/***************************************************************************
Start the video hardware emulation.
***************************************************************************/
VIDEO_START( gng )
{
gng_state *state = machine.driver_data<gng_state>();
state->m_fg_tilemap = tilemap_create(machine, get_fg_tile_info, tilemap_scan_rows, 8, 8, 32, 32);
state->m_bg_tilemap = tilemap_create(machine, get_bg_tile_info, tilemap_scan_cols, 16, 16, 32, 32);
tilemap_set_transparent_pen(state->m_fg_tilemap, 3);
tilemap_set_transmask(state->m_bg_tilemap, 0, 0xff, 0x00); /* split type 0 is totally transparent in front half */
tilemap_set_transmask(state->m_bg_tilemap, 1, 0x41, 0xbe); /* split type 1 has pens 0 and 6 transparent in front half */
}
/***************************************************************************
Memory handlers
***************************************************************************/
WRITE8_HANDLER( gng_fgvideoram_w )
{
gng_state *state = space->machine().driver_data<gng_state>();
state->m_fgvideoram[offset] = data;
tilemap_mark_tile_dirty(state->m_fg_tilemap, offset & 0x3ff);
}
WRITE8_HANDLER( gng_bgvideoram_w )
{
gng_state *state = space->machine().driver_data<gng_state>();
state->m_bgvideoram[offset] = data;
tilemap_mark_tile_dirty(state->m_bg_tilemap, offset & 0x3ff);
}
WRITE8_HANDLER( gng_bgscrollx_w )
{
gng_state *state = space->machine().driver_data<gng_state>();
state->m_scrollx[offset] = data;
tilemap_set_scrollx(state->m_bg_tilemap, 0, state->m_scrollx[0] + 256 * state->m_scrollx[1]);
}
WRITE8_HANDLER( gng_bgscrolly_w )
{
gng_state *state = space->machine().driver_data<gng_state>();
state->m_scrolly[offset] = data;
tilemap_set_scrolly(state->m_bg_tilemap, 0, state->m_scrolly[0] + 256 * state->m_scrolly[1]);
}
WRITE8_HANDLER( gng_flipscreen_w )
{
flip_screen_set(space->machine(), ~data & 1);
}
/***************************************************************************
Display refresh
***************************************************************************/
static void draw_sprites( running_machine &machine, bitmap_t *bitmap, const rectangle *cliprect )
{
UINT8 *buffered_spriteram = machine.generic.buffered_spriteram.u8;
const gfx_element *gfx = machine.gfx[2];
int offs;
for (offs = machine.generic.spriteram_size - 4; offs >= 0; offs -= 4)
{
UINT8 attributes = buffered_spriteram[offs + 1];
int sx = buffered_spriteram[offs + 3] - 0x100 * (attributes & 0x01);
int sy = buffered_spriteram[offs + 2];
int flipx = attributes & 0x04;
int flipy = attributes & 0x08;
if (flip_screen_get(machine))
{
sx = 240 - sx;
sy = 240 - sy;
flipx = !flipx;
flipy = !flipy;
}
drawgfx_transpen(bitmap,cliprect,gfx,
buffered_spriteram[offs] + ((attributes << 2) & 0x300),
(attributes >> 4) & 3,
flipx,flipy,
sx,sy,15);
}
}
SCREEN_UPDATE( gng )
{
gng_state *state = screen->machine().driver_data<gng_state>();
tilemap_draw(bitmap, cliprect, state->m_bg_tilemap, TILEMAP_DRAW_LAYER1, 0);
draw_sprites(screen->machine(), bitmap, cliprect);
tilemap_draw(bitmap, cliprect, state->m_bg_tilemap, TILEMAP_DRAW_LAYER0, 0);
tilemap_draw(bitmap, cliprect, state->m_fg_tilemap, 0, 0);
return 0;
}
SCREEN_EOF( gng )
{
address_space *space = machine.device("maincpu")->memory().space(AS_PROGRAM);
buffer_spriteram_w(space, 0, 0);
}