bsnes/sfc/coprocessor/sharprtc/time.cpp

82 lines
1.8 KiB
C++

const unsigned SharpRTC::daysinmonth[12] = {31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31};
void SharpRTC::tick_second() {
if(++second < 60) return;
second = 0;
tick_minute();
}
void SharpRTC::tick_minute() {
if(++minute < 60) return;
minute = 0;
tick_hour();
}
void SharpRTC::tick_hour() {
if(++hour < 24) return;
hour = 0;
tick_day();
}
void SharpRTC::tick_day() {
unsigned days = daysinmonth[month % 12];
//add one day for leap years
if(year % 400 == 0) days++;
else if(year % 100 == 0);
else if(year % 4 == 0) days++;
if(day++ < days) return;
day = 1;
tick_month();
}
void SharpRTC::tick_month() {
if(month++ < 12) return;
month = 1;
tick_year();
}
void SharpRTC::tick_year() {
year++;
year = (uint12)year;
}
//returns day of week for specified date
//eg 0 = Sunday, 1 = Monday, ... 6 = Saturday
//usage: calculate_weekday(2008, 1, 1) returns weekday of January 1st, 2008
unsigned SharpRTC::calculate_weekday(unsigned year, unsigned month, unsigned day) {
unsigned y = 1000, m = 1; //SharpRTC epoch is 1000-01-01
unsigned sum = 0; //number of days passed since epoch
year = max(1000, year);
month = max(1, min(12, month));
day = max(1, min(31, day));
while(y < year) {
bool leapyear = false;
if(y % 4 == 0) {
leapyear = true;
if(y % 100 == 0 && y % 400 != 0) leapyear = false;
}
sum += 365 + leapyear;
y++;
}
while(m < month) {
unsigned days = daysinmonth[m - 1];
bool leapyearmonth = false;
if(days == 28) {
if(y % 4 == 0) {
leapyearmonth = true;
if(y % 100 == 0 && y % 400 != 0) leapyearmonth = false;
}
}
sum += days + leapyearmonth;
m++;
}
sum += day - 1;
return (sum + 3) % 7; //1000-01-01 was a Wednesday
}