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

                          -= Yun Sung 16 Bit Games =-

                    driver by   Luca Elia (l.elia@tin.it)


    [ 2 Scrolling Layers ]

    Tiles are 16 x 16 x 8. The layout of the tilemap is a bit weird:
    16 consecutive tile codes define a vertical column.
    16 columns form a page (256 x 256).
    The tilemap is made of 4 x 4 pages (1024 x 1024)

    [ 512? Sprites ]

    Sprites are 16 x 16 x 4 in size. There's RAM for 512, but
    the game just copies 384 entries.


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

#include "driver.h"
#include "vidhrdw/generic.h"

/* Variables that driver has access to: */

data16_t *yunsun16_vram_0,   *yunsun16_vram_1;
data16_t *yunsun16_scroll_0, *yunsun16_scroll_1;
data16_t *yunsun16_priority;


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


                                    Tilemaps


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

static struct tilemap *tilemap_0, *tilemap_1;

#define TMAP_GFX			(0)
#define TILES_PER_PAGE_X	(0x10)
#define TILES_PER_PAGE_Y	(0x10)
#define PAGES_PER_TMAP_X	(0x4)
#define PAGES_PER_TMAP_Y	(0x4)

UINT32 yunsun16_tilemap_scan_pages(UINT32 col,UINT32 row,UINT32 num_cols,UINT32 num_rows)
{
	return	(row / TILES_PER_PAGE_Y) * TILES_PER_PAGE_X * TILES_PER_PAGE_Y * PAGES_PER_TMAP_X +
			(row % TILES_PER_PAGE_Y) +

			(col / TILES_PER_PAGE_X) * TILES_PER_PAGE_X * TILES_PER_PAGE_Y +
			(col % TILES_PER_PAGE_X) * TILES_PER_PAGE_Y;
}

static void get_tile_info_0(int tile_index)
{
	data16_t code = yunsun16_vram_0[ 2 * tile_index + 0 ];
	data16_t attr = yunsun16_vram_0[ 2 * tile_index + 1 ];
	SET_TILE_INFO(
			TMAP_GFX,
			code,
			attr & 0xf,
			0)
}

static void get_tile_info_1(int tile_index)
{
	data16_t code = yunsun16_vram_1[ 2 * tile_index + 0 ];
	data16_t attr = yunsun16_vram_1[ 2 * tile_index + 1 ];
	SET_TILE_INFO(
			TMAP_GFX,
			code,
			attr & 0xf,
			0)
}

WRITE16_HANDLER( yunsun16_vram_0_w )
{
	data16_t old_data	=	yunsun16_vram_0[offset];
	data16_t new_data	=	COMBINE_DATA(&yunsun16_vram_0[offset]);
	if (old_data != new_data)	tilemap_mark_tile_dirty(tilemap_0,offset/2);
}

WRITE16_HANDLER( yunsun16_vram_1_w )
{
	data16_t old_data	=	yunsun16_vram_1[offset];
	data16_t new_data	=	COMBINE_DATA(&yunsun16_vram_1[offset]);
	if (old_data != new_data)	tilemap_mark_tile_dirty(tilemap_1,offset/2);
}


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


                            Video Hardware Init


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

static int sprites_scrolldx, sprites_scrolldy;

VIDEO_START( yunsun16 )
{
	tilemap_0 = tilemap_create(	get_tile_info_0,yunsun16_tilemap_scan_pages,
								TILEMAP_TRANSPARENT,
								16,16,
								TILES_PER_PAGE_X*PAGES_PER_TMAP_X,TILES_PER_PAGE_Y*PAGES_PER_TMAP_Y);

	tilemap_1 = tilemap_create(	get_tile_info_1,yunsun16_tilemap_scan_pages,
								TILEMAP_TRANSPARENT,
								16,16,
								TILES_PER_PAGE_X*PAGES_PER_TMAP_X,TILES_PER_PAGE_Y*PAGES_PER_TMAP_Y);

	if (!tilemap_0 || !tilemap_1)	return 1;

	sprites_scrolldx = -0x40;
	sprites_scrolldy = -0x0f;
	tilemap_set_scrolldx(tilemap_0,-0x34,0);
	tilemap_set_scrolldx(tilemap_1,-0x38,0);

	tilemap_set_scrolldy(tilemap_0,-0x10,0);
	tilemap_set_scrolldy(tilemap_1,-0x10,0);

	tilemap_set_transparent_pen(tilemap_0,0xff);
	tilemap_set_transparent_pen(tilemap_1,0xff);
	return 0;
}


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


                                Sprites Drawing


        0.w                             X

        2.w                             Y

        4.w                             Code

        6.w     fedc ba98 7--- ----
                ---- ---- -6-- ----     Flip Y
                ---- ---- --5- ----     Flip X
                ---- ---- ---4 3210     Color


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

static void yunsun16_draw_sprites(struct mame_bitmap *bitmap,const struct rectangle *cliprect)
{
	int offs;

	int max_x		=	Machine->visible_area.max_x+1;
	int max_y		=	Machine->visible_area.max_y+1;

	int pri			=	*yunsun16_priority & 7;
	int pri_mask;

	switch( pri & 7 )
	{
		case 5:		pri_mask = (1<<1)|(1<<2)|(1<<3);	break;
		case 6:		pri_mask = (1<<2)|(1<<3);			break;
		case 7:
		default:	pri_mask = 0;
	}

	for ( offs = (spriteram_size-8)/2 ; offs >= 0; offs -= 8/2 )
	{
		int x		=	spriteram16[offs + 0];
		int y		=	spriteram16[offs + 1];
		int code	=	spriteram16[offs + 2];
		int attr	=	spriteram16[offs + 3];
		int flipx	=	attr & 0x20;
		int flipy	=	attr & 0x40;


		x	+=	sprites_scrolldx;
		y	+=	sprites_scrolldy;

		if (flip_screen)	/* not used? */
		{
			flipx = !flipx;		x = max_x - x - 16;
			flipy = !flipy;		y = max_y - y - 16;
		}

		pdrawgfx(	bitmap,Machine->gfx[1],
					code,
					attr & 0x1f,
					flipx, flipy,
					x,y,
					cliprect,TRANSPARENCY_PEN,15,
					pri_mask	);
	}
}


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


                                Screen Drawing


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


VIDEO_UPDATE( yunsun16 )
{
	tilemap_set_scrollx(tilemap_0, 0, yunsun16_scroll_0[ 0 ]);
	tilemap_set_scrolly(tilemap_0, 0, yunsun16_scroll_0[ 1 ]);

	tilemap_set_scrollx(tilemap_1, 0, yunsun16_scroll_1[ 0 ]);
	tilemap_set_scrolly(tilemap_1, 0, yunsun16_scroll_1[ 1 ]);

/*  usrintf_showmessage("%04X", *yunsun16_priority); */

	fillbitmap(priority_bitmap,0,cliprect);

	/* The color of the this layer's transparent pen goes below everything */
	tilemap_draw(bitmap,cliprect,tilemap_0, TILEMAP_IGNORE_TRANSPARENCY, 0);

	tilemap_draw(bitmap,cliprect,tilemap_0, 0, 1);

	tilemap_draw(bitmap,cliprect,tilemap_1, 0, 2);

	yunsun16_draw_sprites(bitmap,cliprect);

	/* tilemap.c only copes with screen widths which are a multiple of 8 pixels */
	if ( (Machine->drv->screen_width-1-Machine->visible_area.max_x) & 7 )
	{
		struct rectangle clip;
		clip.min_x = Machine->visible_area.max_x+1;
		clip.max_x = Machine->drv->screen_width-1;
		clip.min_y = Machine->visible_area.min_y;
		clip.max_y = Machine->visible_area.max_y;
		sect_rect(&clip,cliprect);
		fillbitmap(bitmap,Machine->pens[0],&clip);
	}
}
