/***************************************************************************
video.c
Functions to emulate the video hardware of the machine.
***************************************************************************/
#include "driver.h"
UINT8 *gng_fgvideoram;
UINT8 *gng_bgvideoram;
static tilemap *bg_tilemap,*fg_tilemap;
static UINT8 scrollx[2];
static UINT8 scrolly[2];
/***************************************************************************
Callbacks for the TileMap code
***************************************************************************/
static TILE_GET_INFO( get_fg_tile_info )
{
UINT8 attr = gng_fgvideoram[tile_index + 0x400];
SET_TILE_INFO(
0,
gng_fgvideoram[tile_index] + ((attr & 0xc0) << 2),
attr & 0x0f,
TILE_FLIPYX((attr & 0x30) >> 4));
}
static TILE_GET_INFO( get_bg_tile_info )
{
UINT8 attr = gng_bgvideoram[tile_index + 0x400];
SET_TILE_INFO(
1,
gng_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 )
{
fg_tilemap = tilemap_create(get_fg_tile_info,tilemap_scan_rows,TILEMAP_TYPE_PEN,8,8,32,32);
bg_tilemap = tilemap_create(get_bg_tile_info,tilemap_scan_cols,TILEMAP_TYPE_PEN, 16,16,32,32);
tilemap_set_transparent_pen(fg_tilemap,3);
tilemap_set_transmask(bg_tilemap,0,0xff,0x00); /* split type 0 is totally transparent in front half */
tilemap_set_transmask(bg_tilemap,1,0x41,0xbe); /* split type 1 has pens 0 and 6 transparent in front half */
/* register to save state */
state_save_register_global_array(scrollx);
state_save_register_global_array(scrolly);
}
/***************************************************************************
Memory handlers
***************************************************************************/
WRITE8_HANDLER( gng_fgvideoram_w )
{
gng_fgvideoram[offset] = data;
tilemap_mark_tile_dirty(fg_tilemap,offset & 0x3ff);
}
WRITE8_HANDLER( gng_bgvideoram_w )
{
gng_bgvideoram[offset] = data;
tilemap_mark_tile_dirty(bg_tilemap,offset & 0x3ff);
}
WRITE8_HANDLER( gng_bgscrollx_w )
{
scrollx[offset] = data;
tilemap_set_scrollx( bg_tilemap, 0, scrollx[0] + 256 * scrollx[1] );
}
WRITE8_HANDLER( gng_bgscrolly_w )
{
scrolly[offset] = data;
tilemap_set_scrolly( bg_tilemap, 0, scrolly[0] + 256 * scrolly[1] );
}
WRITE8_HANDLER( gng_flipscreen_w )
{
flip_screen_set(~data & 1);
}
/***************************************************************************
Display refresh
***************************************************************************/
static void draw_sprites(running_machine *machine, mame_bitmap *bitmap, const rectangle *cliprect)
{
const gfx_element *gfx = machine->gfx[2];
int offs;
for (offs = 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)
{
sx = 240 - sx;
sy = 240 - sy;
flipx = !flipx;
flipy = !flipy;
}
drawgfx(bitmap,gfx,
buffered_spriteram[offs] + ((attributes<<2) & 0x300),
(attributes >> 4) & 3,
flipx,flipy,
sx,sy,
cliprect,TRANSPARENCY_PEN,15);
}
}
VIDEO_UPDATE( gng )
{
tilemap_draw(bitmap,cliprect,bg_tilemap,TILEMAP_DRAW_LAYER1,0);
draw_sprites(machine,bitmap,cliprect);
tilemap_draw(bitmap,cliprect,bg_tilemap,TILEMAP_DRAW_LAYER0,0);
tilemap_draw(bitmap,cliprect,fg_tilemap,0,0);
return 0;
}
VIDEO_EOF( gng )
{
buffer_spriteram_w(0,0);
}