time/rtc/source/main.c

#include <3ds.h>
#include <stdio.h>
#include <time.h>
 
const char* const months[12] = {"January", "February", "March", "April", "May", "June", "July", "August", "September", "October", "November", "December"};
 
const char* const weekDays[7] = {"Sunday", "Monday", "Tuesday", "Wednesday", "Thursday", "Friday", "Saturday"};
 
const u16 daysAtStartOfMonthLUT[12] =
{
 0 % 7, //january 31
 31 % 7, //february 28+1(leap year)
 59 % 7, //march 31
 90 % 7, //april 30
 120 % 7, //may 31
 151 % 7, //june 30
 181 % 7, //july 31
 212 % 7, //august 31
 243 % 7, //september 30
 273 % 7, //october 31
 304 % 7, //november 30
 334 % 7 //december 31
};
 
static inline bool isLeapYear(int year)
{
 return (year%4) == 0 && !((year%100) == 0 && (year%400) != 0);
}
 
static inline int getDayOfWeek(int day, int month, int year)
{
 //http://en.wikipedia.org/wiki/Calculating_the_day_of_the_week
 day += 2*(3-((year/100)%4));
 year %= 100;
 day += year + (year/4);
 day += daysAtStartOfMonthLUT[month] - (isLeapYear(year) && (month <= 1));
 return day % 7;
}
 
int main(int argc, char **argv)
{
 // Initialize services
 gfxInitDefault();
 
 //Initialize console on top screen. Using NULL as the second argument tells the console library to use the internal console structure as current one
 consoleInit(GFX_TOP, NULL);
 
 printf("\x1b[30;16HPress Start to exit.");
 
 // Main loop
 while (aptMainLoop())
 {
 //Scan all the inputs. This should be done once for each frame
 hidScanInput();
 
 //hidKeysDown returns information about which buttons have been just pressed (and they weren't in the previous frame)
 u32 kDown = hidKeysDown();
 
 if (kDown & KEY_START) break; // break in order to return to hbmenu
 
 //Print current time
 time_t unixTime = time(NULL);
 struct tm* timeStruct = gmtime((const time_t *)&unixTime);
 
 int hours = timeStruct->tm_hour;
 int minutes = timeStruct->tm_min;
 int seconds = timeStruct->tm_sec;
 int day = timeStruct->tm_mday;
 int month = timeStruct->tm_mon;
 int year = timeStruct->tm_year +1900;
 
 printf("\x1b[1;1H%02i:%02i:%02i", hours, minutes, seconds);
 printf("\n%s %s %i %i", weekDays[getDayOfWeek(day, month, year)], months[month], day, year);
 
 // Flush and swap framebuffers
 gfxFlushBuffers();
 gfxSwapBuffers();
 
 //Wait for VBlank
 gspWaitForVBlank();
 }
 
 // Exit services
 gfxExit();
 
 return 0;
}