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Merge pull request #262 from rieck/timestamp-fix

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Fix for incorrect conversion from `watch_date_time` to Unix time.
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Wesley Aptekar-Cassels 2023-11-19 00:10:19 -05:00 committed by GitHub
parent c4a5cb463e 0f9bb0bd37
commit 76b580a5be
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1 changed files with 74 additions and 6 deletions
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watch-library/shared/watch/watch_utility.c
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@ -102,13 +102,81 @@ uint16_t watch_utility_days_since_new_year(uint16_t year, uint8_t month, uint8_t
return (is_leap(year) && (month > 2) ? 1 : 0) + DAYS_SO_FAR[month - 1] + day;
}
uint32_t watch_utility_convert_to_unix_time(uint16_t year, uint8_t month, uint8_t day, uint8_t hour, uint8_t minute, uint8_t second, uint32_t utc_offset) {
uint32_t year_adj = year + 4800;
uint32_t leap_days = 1 + (year_adj / 4) - (year_adj / 100) + (year_adj / 400);
uint32_t days = 365 * year_adj + leap_days + watch_utility_days_since_new_year(year, month, day) - 1;
days -= 2472692; /* Adjust to Unix epoch. */
// Function taken from `src/time/__year_to_secs.c` of musl libc
// https://musl.libc.org
static uint32_t __year_to_secs(uint32_t year, int *is_leap)
{
if (year-2ULL <= 136) {
int y = year;
int leaps = (y-68)>>2;
if (!((y-68)&3)) {
leaps--;
if (is_leap) *is_leap = 1;
} else if (is_leap) *is_leap = 0;
return 31536000*(y-70) + 86400*leaps;
}
uint32_t timestamp = days * 86400;
int cycles, centuries, leaps, rem;
if (!is_leap) is_leap = &(int){0};
cycles = (year-100) / 400;
rem = (year-100) % 400;
if (rem < 0) {
cycles--;
rem += 400;
}
if (!rem) {
*is_leap = 1;
centuries = 0;
leaps = 0;
} else {
if (rem >= 200) {
if (rem >= 300) centuries = 3, rem -= 300;
else centuries = 2, rem -= 200;
} else {
if (rem >= 100) centuries = 1, rem -= 100;
else centuries = 0;
}
if (!rem) {
*is_leap = 0;
leaps = 0;
} else {
leaps = rem / 4U;
rem %= 4U;
*is_leap = !rem;
}
}
leaps += 97*cycles + 24*centuries - *is_leap;
return (year-100) * 31536000LL + leaps * 86400LL + 946684800 + 86400;
}
// Function taken from `src/time/__month_to_secs.c` of musl libc
// https://musl.libc.org
static int __month_to_secs(int month, int is_leap)
{
static const int secs_through_month[] = {
0, 31*86400, 59*86400, 90*86400,
120*86400, 151*86400, 181*86400, 212*86400,
243*86400, 273*86400, 304*86400, 334*86400 };
int t = secs_through_month[month];
if (is_leap && month >= 2) t+=86400;
return t;
}
// Function adapted from `src/time/__tm_to_secs.c` of musl libc
// https://musl.libc.org
uint32_t watch_utility_convert_to_unix_time(uint16_t year, uint8_t month, uint8_t day, uint8_t hour, uint8_t minute, uint8_t second, uint32_t utc_offset) {
int is_leap;
// POSIX tm struct starts year at 1900 and month at 0
// https://pubs.opengroup.org/onlinepubs/9699919799/basedefs/time.h.html
uint32_t timestamp = __year_to_secs(year - 1900, &is_leap);
timestamp += __month_to_secs(month - 1, is_leap);
// Regular conversion from musl libc
timestamp += (day - 1) * 86400;
timestamp += hour * 3600;
timestamp += minute * 60;
timestamp += second;