BTRNREG
data->window_type[i] = (BTRNREG(data) & 0xff); /* B0-7 */
data->window_type[i] |= (BTRNREG(data) & 0xff) << 8; /* B8-15 */
data->window_type[i] |= (BTRNREG(data) & 0xff) << 16; /* B16-23 */