#include "driver.h"
#include "iqblock.h"


data8_t *iqblock_bgvideoram;
data8_t *iqblock_fgscroll;
data8_t *iqblock_fgvideoram;
int iqblock_videoenable;

static struct tilemap *bg_tilemap,*fg_tilemap;


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

  Callbacks for the TileMap code

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

static void get_bg_tile_info(int tile_index)
{
	int code = iqblock_bgvideoram[tile_index] + (iqblock_bgvideoram[tile_index + 0x800] << 8);
	SET_TILE_INFO(
			0,
			code & 0x1fff,
			2*(code >> 13)+1,
			0)
}

static void get_fg_tile_info(int tile_index)
{
	int code = iqblock_fgvideoram[tile_index];
	SET_TILE_INFO(
			1,
			code & 0x7f,
			(code & 0x80) ? 3 : 0,
			0)
}



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

  Start the video hardware emulation.

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

VIDEO_START( iqblock )
{
	bg_tilemap = tilemap_create(get_bg_tile_info,tilemap_scan_rows,TILEMAP_OPAQUE,     8, 8,64,32);
	fg_tilemap = tilemap_create(get_fg_tile_info,tilemap_scan_rows,TILEMAP_TRANSPARENT,8,32,64, 8);

	if (!bg_tilemap || !fg_tilemap)
		return 1;

	tilemap_set_transparent_pen(fg_tilemap,0);
	tilemap_set_scroll_cols(fg_tilemap,64);

	return 0;
}



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

  Memory handlers

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

WRITE_HANDLER( iqblock_fgvideoram_w )
{
	iqblock_fgvideoram[offset] = data;
	tilemap_mark_tile_dirty(fg_tilemap,offset);
}

WRITE_HANDLER( iqblock_bgvideoram_w )
{
	iqblock_bgvideoram[offset] = data;
	tilemap_mark_tile_dirty(bg_tilemap,offset & 0x7ff);
}

READ_HANDLER( iqblock_bgvideoram_r )
{
	return iqblock_bgvideoram[offset];
}

WRITE_HANDLER( iqblock_fgscroll_w )
{
	tilemap_set_scrolly(fg_tilemap,offset,data);
}



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

  Display refresh

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

VIDEO_UPDATE( iqblock )
{
	if (!iqblock_videoenable) return;

	tilemap_draw(bitmap,cliprect,bg_tilemap,0,0);
	tilemap_draw(bitmap,cliprect,fg_tilemap,0,0);
}
