/***************************************************************************

  Video Hardware for some Technos games:
    Double Dragon, Double Dragon bootleg, Double Dragon II and China Gate

  Two Tile layers.
    Background layer is 512x512 , tiles are 16x16
    Top        layer is 256x256 , tiles are 8x8

  Sprites are 16x16, 16x32, 32x16, or 32x32 (attribute bits set dimension)


BG Tile Layout
  0          1
  ---- -xxx  xxxx xxxx  = Tile number
  --xx x---  ---- ----  = Color
  -x-- ----  ---- ----  = X Flip
  x--- ----  ---- ----  = Y Flip


Top Tile layout.
  0          1
  ---- xxxx  xxxx xxxx  = Tile number
  xxxx ----  ---- ----  = Color (China Gate)
  xxx- ----  ---- ----  = Color (Double Dragon)


Sprite layout.
  0          1          2          3          4
  ---- ----  ---- ----  ---- xxxx  xxxx xxxx  ---- ----  = Sprite number
  ---- ----  ---- ----  -xxx ----  ---- ----  ---- ----  = Color
  xxxx xxxx  ---- ----  ---- ----  ---- ----  ---- ----  = Y position
  ---- ----  ---- ---x  ---- ----  ---- ----  ---- ----  = Y MSb position ???
  ---- ----  ---- ----  ---- ----  ---- ----  xxxx xxxx  = X position
  ---- ----  ---- --x-  ---- ----  ---- ----  ---- ----  = X MSb position ???
  ---- ----  ---- -x--  ---- ----  ---- ----  ---- ----  = Y Flip
  ---- ----  ---- x---  ---- ----  ---- ----  ---- ----  = X Flip
  ---- ----  --xx ----  ---- ----  ---- ----  ---- ----  = Sprite Dimension
  ---- ----  x--- ----  ---- ----  ---- ----  ---- ----  = Visible

***************************************************************************/

#include "driver.h"


UINT8 *ddragon_bgvideoram,*ddragon_fgvideoram;
UINT16 ddragon_scrollx_hi, ddragon_scrolly_hi;
UINT8 *ddragon_scrollx_lo;
UINT8 *ddragon_scrolly_lo;
UINT8 *ddragon_spriteram;
UINT8 technos_video_hw;

static tilemap *fg_tilemap,*bg_tilemap;



/***************************************************************************

  Callbacks for the TileMap code

***************************************************************************/

static TILEMAP_MAPPER( background_scan )
{
	/* logical (col,row) -> memory offset */
	return (col & 0x0f) + ((row & 0x0f) << 4) + ((col & 0x10) << 4) + ((row & 0x10) << 5);
}

static TILE_GET_INFO( get_bg_tile_info )
{
	UINT8 attr = ddragon_bgvideoram[2*tile_index];
	SET_TILE_INFO(
			2,
			ddragon_bgvideoram[2*tile_index+1] + ((attr & 0x07) << 8),
			(attr >> 3) & 0x07,
			TILE_FLIPYX((attr & 0xc0) >> 6));
}

static TILE_GET_INFO( get_fg_tile_info )
{
	UINT8 attr = ddragon_fgvideoram[2*tile_index];
	SET_TILE_INFO(
			0,
			ddragon_fgvideoram[2*tile_index+1] + ((attr & 0x07) << 8),
			attr >> 5,
			0);
}

static TILE_GET_INFO( get_fg_16color_tile_info )
{
	UINT8 attr = ddragon_fgvideoram[2*tile_index];
	SET_TILE_INFO(
			0,
			ddragon_fgvideoram[2*tile_index+1] + ((attr & 0x0f) << 8),
			attr >> 4,
			0);
}


/***************************************************************************

  Start the video hardware emulation.

***************************************************************************/

VIDEO_START( ddragon )
{
	bg_tilemap = tilemap_create(machine, get_bg_tile_info,background_scan,  16,16,32,32);
	fg_tilemap = tilemap_create(machine, get_fg_tile_info,tilemap_scan_rows, 8, 8,32,32);

	tilemap_set_transparent_pen(fg_tilemap,0);
	tilemap_set_scrolldx(fg_tilemap, 0, 384 - 256);
	tilemap_set_scrolldx(bg_tilemap, 0, 384 - 256);
	tilemap_set_scrolldy(fg_tilemap, -8, -8);
	tilemap_set_scrolldy(bg_tilemap, -8, -8);

	state_save_register_global(machine, ddragon_scrollx_hi);
	state_save_register_global(machine, ddragon_scrolly_hi);
}

VIDEO_START( chinagat )
{
	bg_tilemap = tilemap_create(machine, get_bg_tile_info,background_scan,16,16,32,32);
	fg_tilemap = tilemap_create(machine, get_fg_16color_tile_info,tilemap_scan_rows,8, 8,32,32);

	tilemap_set_transparent_pen(fg_tilemap,0);
	tilemap_set_scrolldy(fg_tilemap, -8, -8);
	tilemap_set_scrolldy(bg_tilemap, -8, -8);

	state_save_register_global(machine, ddragon_scrollx_hi);
	state_save_register_global(machine, ddragon_scrolly_hi);
}


/***************************************************************************

  Memory handlers

***************************************************************************/

WRITE8_HANDLER( ddragon_bgvideoram_w )
{
	ddragon_bgvideoram[offset] = data;
	tilemap_mark_tile_dirty(bg_tilemap,offset/2);
}

WRITE8_HANDLER( ddragon_fgvideoram_w )
{
	ddragon_fgvideoram[offset] = data;
	tilemap_mark_tile_dirty(fg_tilemap,offset/2);
}


/***************************************************************************

  Display refresh

***************************************************************************/

#define DRAW_SPRITE( order, sx, sy ) drawgfx_transpen( bitmap, \
					cliprect,gfx, \
					(which+order),color,flipx,flipy,sx,sy,0);

static void draw_sprites(running_machine* machine, bitmap_t *bitmap,const rectangle *cliprect)
{
	const gfx_element *gfx = machine->gfx[1];

	UINT8 *src;
	int i;

	if ( technos_video_hw == 1 ) {		/* China Gate Sprite RAM */
		src = (UINT8 *) (spriteram);
	} else {
		src = (UINT8 *) (&( ddragon_spriteram[0x800] ));
	}

	for( i = 0; i < ( 64 * 5 ); i += 5 ) {
		int attr = src[i+1];
		if ( attr & 0x80 ) { /* visible */
			int sx = 240 - src[i+4] + ( ( attr & 2 ) << 7 );
			int sy = 232 - src[i+0] + ( ( attr & 1 ) << 8 );
			int size = ( attr & 0x30 ) >> 4;
			int flipx = ( attr & 8 );
			int flipy = ( attr & 4 );
			int dx = -16,dy = -16;

			int which;
			int color;

			if ( technos_video_hw == 2 )		/* Double Dragon 2 */
			{
				color = ( src[i+2] >> 5 );
				which = src[i+3] + ( ( src[i+2] & 0x1f ) << 8 );
			}
			else
			{
				if ( technos_video_hw == 1 )		/* China Gate */
				{
					if ((sx < -7) && (sx > -16)) sx += 256; /* fix sprite clip */
					if ((sy < -7) && (sy > -16)) sy += 256; /* fix sprite clip */
				}
				color = ( src[i+2] >> 4 ) & 0x07;
				which = src[i+3] + ( ( src[i+2] & 0x0f ) << 8 );
			}

			if (flip_screen_get(machine))
			{
				sx = 240 - sx;
				sy = 256 - sy;
				flipx = !flipx;
				flipy = !flipy;
				dx = -dx;
				dy = -dy;
			}

			which &= ~size;

			switch ( size ) {
				case 0: /* normal */
				DRAW_SPRITE( 0, sx, sy );
				break;

				case 1: /* double y */
				DRAW_SPRITE( 0, sx, sy + dy );
				DRAW_SPRITE( 1, sx, sy );
				break;

				case 2: /* double x */
				DRAW_SPRITE( 0, sx + dx, sy );
				DRAW_SPRITE( 2, sx, sy );
				break;

				case 3:
				DRAW_SPRITE( 0, sx + dx, sy + dy );
				DRAW_SPRITE( 1, sx + dx, sy );
				DRAW_SPRITE( 2, sx, sy + dy );
				DRAW_SPRITE( 3, sx, sy );
				break;
			}
		}
	}
}

#undef DRAW_SPRITE


VIDEO_UPDATE( ddragon )
{
	int scrollx = ddragon_scrollx_hi + *ddragon_scrollx_lo;
	int scrolly = ddragon_scrolly_hi + *ddragon_scrolly_lo;

	tilemap_set_scrollx(bg_tilemap,0,scrollx);
	tilemap_set_scrolly(bg_tilemap,0,scrolly);

	tilemap_draw(bitmap,cliprect,bg_tilemap,0,0);
	draw_sprites(screen->machine, bitmap,cliprect);
	tilemap_draw(bitmap,cliprect,fg_tilemap,0,0);
	return 0;
}
