void ds1302_check_rtc(void)
{
uint8_t buffer[7];
ds1302_read_clock(buffer, 7); /* read all calendar data */
if(buffer[0] & 0x80){ /* is the clock halted? */
kputs("ds1302: start clock\n");
ds1302_write_seconds(buffer[0] & 0x7F); /* start it */
}
}
uint32_t ds1302_read_rtc(void)
{
uint32_t ret;
uint8_t buffer[7];
uint8_t year, month, day, hour, minute, second;
ds1302_read_clock(buffer, 7); /* read all calendar data */
year = uint8_from_bcd(buffer[6]);
month = uint8_from_bcd(buffer[4] & 0x1F);
day = uint8_from_bcd(buffer[3] & 0x3F);
if(buffer[2] & 0x80) /* AM/PM 12-hour mode */
hour = uint8_from_bcd(buffer[2] & 0x1F) + (buffer[2] & 0x20 ? 12 : 0);
else /* sensible 24-hour mode */
hour = uint8_from_bcd(buffer[2] & 0x3F);
minute = uint8_from_bcd(buffer[1]);
second = uint8_from_bcd(buffer[0] & 0x7F);
if(buffer[0] & 0x80){ /* is the clock halted? */
kputs("ds1302: start clock\n");
ds1302_write_seconds(second); /* start it */
}
if(year < 70)
year += 100;
/* following code is based on utc_mktime() from ELKS
https://github.com/jbruchon/elks/blob/master/elkscmd/sh_utils/date.c */
/* uses zero-based month index */
month--;
/* calculate days from years */
ret = multiply_8x32(year - 70, 365);
/* count leap days in preceding years */
ret += ((year - 69) >> 2);
/* calculate days from months */
ret += mktime_moffset[month];
/* add in this year's leap day, if any */
if (((year & 3) == 0) && (month > 1)) {
ret ++;
}
/* add in days in this month */
ret += (day - 1);
/* convert to hours */
ret = multiply_8x32(24, ret);
ret += hour;
/* convert to minutes */
ret = multiply_8x32(60, ret);
ret += minute;
/* convert to seconds */
ret = multiply_8x32(60, ret);
ret += second;
/* return the result */
return ret;
}