#include "driver.h"
static UINT8 *cbasebal_textram,*cbasebal_scrollram;
static tilemap *fg_tilemap,*bg_tilemap;
static int tilebank,spritebank;
static int text_on,bg_on,obj_on;
static int flipscreen;
/***************************************************************************
Callbacks for the TileMap code
***************************************************************************/
static TILE_GET_INFO( get_bg_tile_info )
{
UINT8 attr = cbasebal_scrollram[2*tile_index+1];
SET_TILE_INFO(
1,
cbasebal_scrollram[2*tile_index] + ((attr & 0x07) << 8) + 0x800 * tilebank,
(attr & 0xf0) >> 4,
(attr & 0x08) ? TILE_FLIPX : 0);
}
static TILE_GET_INFO( get_fg_tile_info )
{
UINT8 attr = cbasebal_textram[tile_index+0x800];
SET_TILE_INFO(
0,
cbasebal_textram[tile_index] + ((attr & 0xf0) << 4),
attr & 0x07,
(attr & 0x08) ? TILE_FLIPX : 0);
}
/***************************************************************************
Start the video hardware emulation.
***************************************************************************/
VIDEO_START( cbasebal )
{
cbasebal_textram = auto_malloc(0x1000);
cbasebal_scrollram = auto_malloc(0x1000);
bg_tilemap = tilemap_create(get_bg_tile_info,tilemap_scan_rows,TILEMAP_TYPE_PEN, 16,16,64,32);
fg_tilemap = tilemap_create(get_fg_tile_info,tilemap_scan_rows,TILEMAP_TYPE_PEN,8,8,64,32);
tilemap_set_transparent_pen(fg_tilemap,3);
}
/***************************************************************************
Memory handlers
***************************************************************************/
WRITE8_HANDLER( cbasebal_textram_w )
{
cbasebal_textram[offset] = data;
tilemap_mark_tile_dirty(fg_tilemap,offset & 0x7ff);
}
READ8_HANDLER( cbasebal_textram_r )
{
return cbasebal_textram[offset];
}
WRITE8_HANDLER( cbasebal_scrollram_w )
{
cbasebal_scrollram[offset] = data;
tilemap_mark_tile_dirty(bg_tilemap,offset/2);
}
READ8_HANDLER( cbasebal_scrollram_r )
{
return cbasebal_scrollram[offset];
}
WRITE8_HANDLER( cbasebal_gfxctrl_w )
{
/* bit 0 is unknown - toggles continuously */
/* bit 1 is flip screen */
flipscreen = data & 0x02;
tilemap_set_flip(ALL_TILEMAPS,flipscreen ? (TILEMAP_FLIPY | TILEMAP_FLIPX) : 0);
/* bit 2 is unknown - unused? */
/* bit 3 is tile bank */
if (tilebank != ((data & 0x08) >> 3))
{
tilebank = (data & 0x08) >> 3;
tilemap_mark_all_tiles_dirty(bg_tilemap);
}
/* bit 4 is sprite bank */
spritebank = (data & 0x10) >> 4;
/* bits 5 is text enable */
text_on = ~data & 0x20;
/* bits 6-7 are bg/sprite enable (don't know which is which) */
bg_on = ~data & 0x40;
obj_on = ~data & 0x80;
/* other bits unknown, but used */
}
WRITE8_HANDLER( cbasebal_scrollx_w )
{
static UINT8 scroll[2];
scroll[offset] = data;
tilemap_set_scrollx(bg_tilemap,0,scroll[0] + 256 * scroll[1]);
}
WRITE8_HANDLER( cbasebal_scrolly_w )
{
static UINT8 scroll[2];
scroll[offset] = data;
tilemap_set_scrolly(bg_tilemap,0,scroll[0] + 256 * scroll[1]);
}
/***************************************************************************
Display refresh
***************************************************************************/
static void draw_sprites(running_machine *machine, mame_bitmap *bitmap, const rectangle *cliprect)
{
int offs,sx,sy;
/* the last entry is not a sprite, we skip it otherwise spang shows a bubble */
/* moving diagonally across the screen */
for (offs = spriteram_size-8;offs >= 0;offs -= 4)
{
int code = spriteram[offs];
int attr = spriteram[offs+1];
int color = attr & 0x07;
int flipx = attr & 0x08;
sx = spriteram[offs+3] + ((attr & 0x10) << 4);
sy = ((spriteram[offs+2] + 8) & 0xff) - 8;
code += (attr & 0xe0) << 3;
code += spritebank * 0x800;
if (flipscreen)
{
sx = 496 - sx;
sy = 240 - sy;
flipx = !flipx;
}
drawgfx(bitmap,machine->gfx[2],
code,
color,
flipx,flipscreen,
sx,sy,
cliprect,TRANSPARENCY_PEN,15);
}
}
VIDEO_UPDATE( cbasebal )
{
if (bg_on)
tilemap_draw(bitmap,cliprect,bg_tilemap,0,0);
else
fillbitmap(bitmap,machine->pens[768],cliprect);
if (obj_on)
draw_sprites(machine, bitmap,cliprect);
if (text_on)
tilemap_draw(bitmap,cliprect,fg_tilemap,0,0);
return 0;
}