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

    Atari Runaway video emulation

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

#include "driver.h"


static tilemap *bg_tilemap;

UINT8* runaway_video_ram;
UINT8* runaway_sprite_ram;

static int tile_bank = 0;



WRITE8_HANDLER( runaway_paletteram_w )
{
	int R =
		0x21 * ((~data >> 2) & 1) +
		0x47 * ((~data >> 3) & 1) +
		0x97 * ((~data >> 4) & 1);

	int G =
		0x21 * ((~data >> 5) & 1) +
		0x47 * ((~data >> 6) & 1) +
		0x97 * ((~data >> 7) & 1);

	int B =
		0x21 * 0 +
		0x47 * ((~data >> 0) & 1) +
		0x97 * ((~data >> 1) & 1);

	palette_set_color(Machine, offset, R, G, B);
}



WRITE8_HANDLER( runaway_video_ram_w )
{
	if (data != runaway_video_ram[offset])
	{
		tilemap_mark_tile_dirty(bg_tilemap, offset);
	}

	runaway_video_ram[offset] = data;
}



WRITE8_HANDLER( runaway_tile_bank_w )
{
	if ((data & 1) != tile_bank)
	{
		tilemap_mark_all_tiles_dirty(bg_tilemap);
	}

	tile_bank = data & 1;
}


static void runaway_get_tile_info(int tile_index)
{
	UINT8 code = runaway_video_ram[tile_index];

	SET_TILE_INFO(0, ((code & 0x3f) << 1) | ((code & 0x40) >> 6) | (tile_bank << 7), 0, (code & 0x80) ? TILE_FLIPY : 0);
}


static void qwak_get_tile_info(int tile_index)
{
	UINT8 code = runaway_video_ram[tile_index];

	SET_TILE_INFO(0, ((code & 0x7f) << 1) | ((code & 0x80) >> 7), 0, 0);
}



VIDEO_START( runaway )
{
	bg_tilemap = tilemap_create(runaway_get_tile_info, tilemap_scan_rows, TILEMAP_OPAQUE, 8, 8, 32, 30);

	return bg_tilemap == NULL;
}


VIDEO_START( qwak )
{
	bg_tilemap = tilemap_create(qwak_get_tile_info, tilemap_scan_rows, TILEMAP_OPAQUE, 8, 8, 32, 30);

	return bg_tilemap == NULL;
}



VIDEO_UPDATE( runaway )
{
	int i;

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

	for (i = 0; i < 16; i++)
	{
		unsigned code = runaway_sprite_ram[i] & 0x3f;

		int x = runaway_sprite_ram[i + 0x20];
		int y = runaway_sprite_ram[i + 0x10];

		int flipx = runaway_sprite_ram[i] & 0x40;
		int flipy = runaway_sprite_ram[i] & 0x80;

		code |= (runaway_sprite_ram[i + 0x30] << 2) & 0x1c0;

		drawgfx(bitmap, machine->gfx[1],
			code,
			0,
			flipx, flipy,
			x, 240 - y,
			cliprect, TRANSPARENCY_PEN, 0);

		drawgfx(bitmap, machine->gfx[1],
			code,
			0,
			flipx, flipy,
			x - 256, 240 - y,
			cliprect, TRANSPARENCY_PEN, 0);
	}
	return 0;
}


VIDEO_UPDATE( qwak )
{
	int i;

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

	for (i = 0; i < 16; i++)
	{
		unsigned code = runaway_sprite_ram[i] & 0x7f;

		int x = runaway_sprite_ram[i + 0x20];
		int y = runaway_sprite_ram[i + 0x10];

		int flipx = 0;
		int flipy = runaway_sprite_ram[i] & 0x80;

		code |= (runaway_sprite_ram[i + 0x30] << 2) & 0x1c0;

		drawgfx(bitmap, machine->gfx[1],
			code,
			0,
			flipx, flipy,
			x, 240 - y,
			cliprect, TRANSPARENCY_PEN, 0);

		drawgfx(bitmap, machine->gfx[1],
			code,
			0,
			flipx, flipy,
			x - 256, 240 - y,
			cliprect, TRANSPARENCY_PEN, 0);
	}
	return 0;
}
