DS1307_HOUR
ampm_mode = !(data[DS1307_HOUR] & RX8035_HOUR_USE_24);
ampm_mode = data[DS1307_HOUR] & DS1307_HOUR_USE_AMPM;
bct.ispm = (data[DS1307_HOUR] & DS1307_HOUR_IS_PM) != 0;
bct.hour = data[DS1307_HOUR] & hourmask;
data[DS1307_HOUR] = bct.hour | pmflags;