UINT32 mc6845_device::screen_update(screen_device &screen, bitmap_rgb32 &bitmap, const rectangle &cliprect)
{
assert(bitmap.valid());
if (m_has_valid_parameters)
{
assert(!m_update_row_cb.isnull());
/* call the set up function if any */
if (!m_begin_update_cb.isnull())
m_begin_update_cb(bitmap, cliprect);
if (cliprect.min_y == 0)
{
/* read the start address at the beginning of the frame */
m_current_disp_addr = m_disp_start_addr;
}
/* for each row in the visible region */
for (UINT16 y = cliprect.min_y; y <= cliprect.max_y; y++)
{
this->draw_scanline(y, bitmap, cliprect);
}
/* call the tear down function if any */
if (!m_end_update_cb.isnull())
m_end_update_cb(bitmap, cliprect);
}
else
{
if (LOG) logerror("M6845: Invalid screen parameters - display disabled!!!\n");
}
return 0;
}
