text: /***************************************************************************
  
    Target Hits Video Hardware
  
    Functions to emulate the video hardware of the machine
  
  ***************************************************************************/
  
  #include "emu.h"
  
  UINT16 *targeth_spriteram;
  UINT16 *targeth_vregs;
  UINT16 *targeth_videoram;
  
  static tilemap_t *pant[2];
  
  
  /***************************************************************************
  
      Callbacks for the TileMap code
  
  ***************************************************************************/
  
  /*
      Tile format
      -----------
  
      Screen 0 & 1: (64*32, 16x16 tiles)
  
      Word | Bit(s)            | Description
      -----+-FEDCBA98-76543210-+--------------------------
        0  | --xxxxxx xxxxxxxx | code
        0  | xx------ -------- | not used?
        1  | -------- ---xxxxx | color (uses 1st half of the palette)
        1  | -------- --x----- | flip y
        1  | -------- -x------ | flip x
        1  | xxxxxxxx x------- | not used?
  */
  
  static TILE_GET_INFO( get_tile_info_targeth_screen0 )
  {
  	int data = targeth_videoram[tile_index << 1];
  	int data2 = targeth_videoram[(tile_index << 1) + 1];
  	int code = data & 0x3fff;
  
  	SET_TILE_INFO(0, code, data2 & 0x1f, TILE_FLIPXY((data2 >> 5) & 0x03));
  }
  
  static TILE_GET_INFO( get_tile_info_targeth_screen1 )
  {
  	int data = targeth_videoram[(0x2000/2) + (tile_index << 1)];
  	int data2 = targeth_videoram[(0x2000/2) + (tile_index << 1) + 1];
  	int code = data & 0x3fff;
  
  	SET_TILE_INFO(0, code, data2 & 0x1f, TILE_FLIPXY((data2 >> 5) & 0x03));
  }
  
  /***************************************************************************
  
      Memory Handlers
  
  ***************************************************************************/
  
  WRITE16_HANDLER( targeth_vram_w )
  {
  	targeth_videoram[offset] = data;
  	tilemap_mark_tile_dirty(pant[(offset & 0x1fff) >> 12], ((offset << 1) & 0x1fff) >> 2);
  }
  
  
  /***************************************************************************
  
      Start/Stop the video hardware emulation.
  
  ***************************************************************************/
  
  VIDEO_START( targeth )
  {
  	pant[0] = tilemap_create(machine, get_tile_info_targeth_screen0,tilemap_scan_rows,16,16,64,32);
  	pant[1] = tilemap_create(machine, get_tile_info_targeth_screen1,tilemap_scan_rows,16,16,64,32);
  
  	tilemap_set_transparent_pen(pant[0],0);
  }
  
  
  /***************************************************************************
  
      Sprites
  
  ***************************************************************************/
  
  /*
      Sprite Format
      -------------
  
      Word | Bit(s)            | Description
      -----+-FEDCBA98-76543210-+--------------------------
        0  | -------- xxxxxxxx | y position
        0  | --xxxxxx -------- | not used?
        0  | -x------ -------- | flipx
        0  | x------- -------- | flipy
        1  | xxxxxxxx xxxxxxxx | not used?
        2  | ------xx xxxxxxxx | x position
        2  | -xxxxx-- -------- | sprite color (uses 2nd half of the palette)
        3  | --xxxxxx xxxxxxxx | sprite code
        3  | xx------ -------- | not used?
  */
  
  static void draw_sprites(running_machine *machine, bitmap_t *bitmap, const rectangle *cliprect)
  {
  	int i;
  	const gfx_element *gfx = machine->gfx[0];
  
  	for (i = 3; i < (0x1000 - 6)/2; i += 4){
  		int sx = targeth_spriteram[i+2] & 0x03ff;
  		int sy = (240 - (targeth_spriteram[i] & 0x00ff)) & 0x00ff;
  		int number = targeth_spriteram[i+3] & 0x3fff;
  		int color = (targeth_spriteram[i+2] & 0x7c00) >> 10;
  		int attr = (targeth_spriteram[i] & 0xfe00) >> 9;
  
  		int xflip = attr & 0x20;
  		int yflip = attr & 0x40;
  
  		drawgfx_transpen(bitmap,cliprect,gfx,number,
  				0x20 + color,xflip,yflip,
  				sx - 0x0f,sy,0);
  	}
  }
  
  /***************************************************************************
  
      Display Refresh
  
  ***************************************************************************/
  
  VIDEO_UPDATE( targeth )
  {
  	/* set scroll registers */
  	tilemap_set_scrolly(pant[0], 0, targeth_vregs[0]);
  	tilemap_set_scrollx(pant[0], 0, targeth_vregs[1] + 0x04);
  	tilemap_set_scrolly(pant[1], 0, targeth_vregs[2]);
  	tilemap_set_scrollx(pant[1], 0, targeth_vregs[3]);
  
  	tilemap_draw(bitmap,cliprect,pant[1],0,0);
  	tilemap_draw(bitmap,cliprect,pant[0],0,0);
  	draw_sprites(screen->machine, bitmap,cliprect);
  
  	return 0;
  }
  