/* Written through port 41-42 */
WRITE8_MEMBER(galivan_state::galivan_scrollx_w)
{
    m_galivan_scrollx[offset] = data;
}

uint32_t galivan_state::screen_update_galivan(screen_device &screen, bitmap_ind16 &bitmap, const rectangle &cliprect)
{
    m_bg_tilemap->set_scrollx(0, m_galivan_scrollx[0] + 256 * (m_galivan_scrollx[1] & 0x07));
    m_bg_tilemap->set_scrolly(0, m_galivan_scrolly[0] + 256 * (m_galivan_scrolly[1] & 0x07));

    if (m_galivan_scrollx[1] & 0x40)
        bitmap.fill(0, cliprect);
    else
        m_bg_tilemap->draw(screen, bitmap, cliprect, 0, 0);

    if (m_galivan_scrollx[1] & 0x20)
    {
        if ((m_galivan_scrollx[1] & 0x80) == 0)
        {
            m_tx_tilemap->draw(screen, bitmap, cliprect, 0, 0);
            m_tx_tilemap->draw(screen, bitmap, cliprect, 1, 0);
        }
        draw_sprites(bitmap, cliprect);
    }
    else
    {
        draw_sprites(bitmap, cliprect);
        if ((m_galivan_scrollx[1] & 0x80) == 0)
        {
            m_tx_tilemap->draw(screen, bitmap, cliprect, 0, 0);
            m_tx_tilemap->draw(screen, bitmap, cliprect, 1, 0);
        }
    }

    return 0;
}