banan-os/BAN/BAN/Time.cpp

71 lines
1.8 KiB
C++

#include <BAN/Time.h>
namespace BAN
{
static constexpr bool is_leap_year(uint64_t year)
{
if (year % 400 == 0)
return true;
if (year % 100 == 0)
return false;
if (year % 4 == 0)
return true;
return false;
}
static constexpr uint64_t leap_days_since_epoch(const BAN::Time& time)
{
uint64_t leap_years = 0;
for (uint32_t year = 1970; year < time.year; year++)
if (is_leap_year(year))
leap_years++;
if (is_leap_year(time.year) && time.month >= 3)
leap_years++;
return leap_years;
}
static constexpr uint64_t month_days[] { 0, 31, 59, 90, 120, 151, 181, 212, 243, 273, 304, 334 };
uint64_t to_unix_time(const BAN::Time& time)
{
uint64_t years = time.year - 1970;
uint64_t days = years * 365 + month_days[time.month - 1] + leap_days_since_epoch(time) + (time.day - 1);
uint64_t hours = days * 24 + time.hour;
uint64_t minutes = hours * 60 + time.minute;
uint64_t seconds = minutes * 60 + time.second;
return seconds;
}
BAN::Time from_unix_time(uint64_t unix_time)
{
BAN::Time time {};
time.second = unix_time % 60; unix_time /= 60;
time.minute = unix_time % 60; unix_time /= 60;
time.hour = unix_time % 24; unix_time /= 24;
uint64_t total_days = unix_time;
time.week_day = (total_days + 4) % 7 + 1;
time.year = 1970;
while (total_days >= 365U + is_leap_year(time.year))
{
total_days -= 365U + is_leap_year(time.year);
time.year++;
}
bool is_leap_day = is_leap_year(time.year) && total_days == month_days[2];
bool had_leap_day = is_leap_year(time.year) && total_days > month_days[2];
for (time.month = 1; time.month < 12; time.month++)
if (total_days < month_days[time.month] + (is_leap_day || had_leap_day))
break;
time.day = total_days - month_days[time.month - 1] + !had_leap_day;
return time;
}
}