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

    Sega System 16B hardware

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

#include "emu.h"
#include "video/segaic16.h"
#include "includes/segas16.h"



/*************************************
 *
 *  Video startup
 *
 *************************************/

static void video_start_common(running_machine &machine, int type)
{
	/* compute palette info */
	segaic16_palette_init(0x800);

	/* initialize the tile/text layers */
	segaic16_tilemap_init(machine, 0, type, 0x000, 0, 2);
}


VIDEO_START( system16b )
{
	video_start_common(machine, SEGAIC16_TILEMAP_16B);
}


VIDEO_START( timscanr )
{
	video_start_common(machine, SEGAIC16_TILEMAP_16B_ALT);
}



/*************************************
 *
 *  Video update
 *
 *************************************/

SCREEN_UPDATE( system16b )
{
	/* if no drawing is happening, fill with black and get out */
	if (!segaic16_display_enable)
	{
		bitmap_fill(bitmap, cliprect, get_black_pen(screen->machine()));
		return 0;
	}

	/* reset priorities */
	bitmap_fill(screen->machine().priority_bitmap, cliprect, 0);

	/* draw background opaquely first, not setting any priorities */
	segaic16_tilemap_draw(screen, bitmap, cliprect, 0, SEGAIC16_TILEMAP_BACKGROUND, 0 | TILEMAP_DRAW_OPAQUE, 0x00);
	segaic16_tilemap_draw(screen, bitmap, cliprect, 0, SEGAIC16_TILEMAP_BACKGROUND, 1 | TILEMAP_DRAW_OPAQUE, 0x00);

	/* draw background again, just to set the priorities on non-transparent pixels */
	segaic16_tilemap_draw(screen, NULL,   cliprect, 0, SEGAIC16_TILEMAP_BACKGROUND, 0, 0x01);
	segaic16_tilemap_draw(screen, NULL,   cliprect, 0, SEGAIC16_TILEMAP_BACKGROUND, 1, 0x02);

	/* draw foreground */
	segaic16_tilemap_draw(screen, bitmap, cliprect, 0, SEGAIC16_TILEMAP_FOREGROUND, 0, 0x02);
	segaic16_tilemap_draw(screen, bitmap, cliprect, 0, SEGAIC16_TILEMAP_FOREGROUND, 1, 0x04);

	/* text layer */
	segaic16_tilemap_draw(screen, bitmap, cliprect, 0, SEGAIC16_TILEMAP_TEXT, 0, 0x04);
	segaic16_tilemap_draw(screen, bitmap, cliprect, 0, SEGAIC16_TILEMAP_TEXT, 1, 0x08);

	/* draw the sprites */
	segaic16_sprites_draw(screen, bitmap, cliprect, 0);
	return 0;
}
