-#define SEC_IN_MIN 60ll
-#define SEC_IN_HOUR (60 * SEC_IN_MIN)
-#define SEC_IN_DAY (24 * SEC_IN_HOUR)
-#define SEC_IN_YEAR (365 * SEC_IN_DAY) /* not leap year */
-/* Unix epoch started at 0:00:00 UTC 1 January 1970 */
-#define UNIX_EPOCH_YEAR 1970
-/* exFAT epoch started at 0:00:00 UTC 1 January 1980 */
-#define EXFAT_EPOCH_YEAR 1980
-/* number of years from Unix epoch to exFAT epoch */
-#define EPOCH_DIFF_YEAR (EXFAT_EPOCH_YEAR - UNIX_EPOCH_YEAR)
-/* number of days from Unix epoch to exFAT epoch (considering leap days) */
-#define EPOCH_DIFF_DAYS (EPOCH_DIFF_YEAR * 365 + EPOCH_DIFF_YEAR / 4)
-/* number of seconds from Unix epoch to exFAT epoch (considering leap days) */
-#define EPOCH_DIFF_SEC (EPOCH_DIFF_DAYS * SEC_IN_DAY)
-/* number of leap years passed from exFAT epoch to the specified year
- (excluding the specified year itself) */
-#define LEAP_YEARS(year) ((EXFAT_EPOCH_YEAR + (year) - 1) / 4 \
- - (EXFAT_EPOCH_YEAR - 1) / 4)
-/* checks whether the specified year is leap */
-#define IS_LEAP_YEAR(year) ((EXFAT_EPOCH_YEAR + (year)) % 4 == 0)
-
-static const time_t days_in_year[] =
-{
- /* Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec */
- 0, 0, 31, 59, 90, 120, 151, 181, 212, 243, 273, 304, 334
-};
-
-time_t exfat_exfat2unix(le16_t date, le16_t time, uint8_t centisec)
-{
- time_t unix_time = EPOCH_DIFF_SEC;
- uint16_t ndate = le16_to_cpu(date);
- uint16_t ntime = le16_to_cpu(time);
-
- uint16_t day = ndate & 0x1f; /* 5 bits, 1-31 */
- uint16_t month = ndate >> 5 & 0xf; /* 4 bits, 1-12 */
- uint16_t year = ndate >> 9; /* 7 bits, 1-127 (+1980) */
-
- uint16_t twosec = ntime & 0x1f; /* 5 bits, 0-29 (2 sec granularity) */
- uint16_t min = ntime >> 5 & 0xf; /* 6 bits, 0-59 */
- uint16_t hour = ntime >> 11; /* 5 bits, 0-23 */
-
- if (day == 0 || month == 0 || month > 12)
- {
- exfat_error("bad date %hu-%02hu-%02hu",
- year + EXFAT_EPOCH_YEAR, month, day);
- return 0;
- }
- if (hour > 23 || min > 59 || twosec > 29)
- {
- exfat_error("bad time %hu:%02hu:%02hu",
- hour, min, twosec * 2);
- return 0;
- }
- if (centisec > 199)
- {
- exfat_error("bad centiseconds count %hhu", centisec);
- return 0;
- }
-
- /* every 4th year between 1904 and 2096 is leap */
- unix_time += year * SEC_IN_YEAR + LEAP_YEARS(year) * SEC_IN_DAY;
- unix_time += days_in_year[month] * SEC_IN_DAY;
- /* if it's leap year and February has passed we should add 1 day */
- if ((EXFAT_EPOCH_YEAR + year) % 4 == 0 && month > 2)
- unix_time += SEC_IN_DAY;
- unix_time += (day - 1) * SEC_IN_DAY;
-
- unix_time += hour * SEC_IN_HOUR;
- unix_time += min * SEC_IN_MIN;
- /* exFAT represents time with 2 sec granularity */
- unix_time += twosec * 2;
- unix_time += centisec / 100;
-
- /* exFAT stores timestamps in local time, so we correct it to UTC */
- unix_time += timezone;
-
- return unix_time;
-}
-
-void exfat_unix2exfat(time_t unix_time, le16_t* date, le16_t* time,
- uint8_t* centisec)
-{
- time_t shift = EPOCH_DIFF_SEC + timezone;
- uint16_t day, month, year;
- uint16_t twosec, min, hour;
- int days;
- int i;
-
- /* time before exFAT epoch cannot be represented */
- if (unix_time < shift)
- unix_time = shift;
-
- unix_time -= shift;
-
- days = unix_time / SEC_IN_DAY;
- year = (4 * days) / (4 * 365 + 1);
- days -= year * 365 + LEAP_YEARS(year);
- month = 0;
- for (i = 1; i <= 12; i++)
- {
- int leap_day = (IS_LEAP_YEAR(year) && i == 2);
- int leap_sub = (IS_LEAP_YEAR(year) && i >= 3);
-
- if (i == 12 || days - leap_sub < days_in_year[i + 1] + leap_day)
- {
- month = i;
- days -= days_in_year[i] + leap_sub;
- break;
- }
- }
- day = days + 1;
-
- hour = (unix_time % SEC_IN_DAY) / SEC_IN_HOUR;
- min = (unix_time % SEC_IN_HOUR) / SEC_IN_MIN;
- twosec = (unix_time % SEC_IN_MIN) / 2;
-
- *date = cpu_to_le16(day | (month << 5) | (year << 9));
- *time = cpu_to_le16(twosec | (min << 5) | (hour << 11));
- if (centisec)
- *centisec = (unix_time % 2) * 100;
-}
-