timedate.c

source code for a sample alarm control panel system using Freescale MC9S12DP256 . The project was im

//=============================================================================
// File: TIMEDATE.C - V1.00
// Rem.: The ACPRD Project Page on the Web -> http://hc12web.de/acprd
//=============================================================================

//-- Includes -----------------------------------------------------------------

#include <stdio.h>
#include "datatypes.h"
#include "timedate.h"

//-- Static Vars --------------------------------------------------------------

const UINT16 days_until_month[24] = {
	0, 31, 59, 90, 120, 151, 181, 212, 243, 273, 304, 334,	// normal year
	0, 31, 60, 91, 121, 152, 182, 213, 244, 274, 305, 335	// leap year
	};

const UINT8 * const wday_name[7] = {
	"Sun", "Mon", "Tue", "Wed", "Thu", "Fri", "Sat"
	};

const UINT8 * const month_name[12] = {
	"Jan", "Feb", "Mar", "Apr", "May", "Jun",
	"Jul", "Aug", "Sep", "Oct", "Nov", "Dec"
	};

volatile time_t systime;	// system timer, incremented every second
struct tm systime_tm;		// static buffer used by gmtime()
#ifdef __USE_ASCTIME
UINT8 systime_str[32];		// static buffer used by asctime() and ctime()
#endif //__USE_ASCTIME

//-- Code ---------------------------------------------------------------------

time_t time(time_t *tptr) {

	time_t t;

	DISABLE_INTERRUPTS();
	t = systime;
	ENABLE_INTERRUPTS();
	if(tptr != NULL) *tptr = t;
	return t;
	}

//-----------------------------------------------------------------------------

UINT16 stime(time_t *tptr) {

	if(tptr != NULL) {
		DISABLE_INTERRUPTS();
		systime = *tptr;
		ENABLE_INTERRUPTS();
		}
	return 0;
	}

//-----------------------------------------------------------------------------

// convert timestamp (seconds since 1970)
// to structured time/date info
//
struct tm *gmtime(const time_t *tptr) {

	UINT32 time;
	UINT16 days, days_p_y, n;
	const UINT16 *days_u_m;

	time = *tptr;						// time in seconds
	systime_tm.tm_sec = (UINT8)(time % 60);
	time /= 60;							// time in minutes
	systime_tm.tm_min = (UINT8)(time % 60);
	time /= 60;							// time in hours
	systime_tm.tm_hour = (UINT8)(time % 24);
	time /= 24;							// time in days since 1970
	systime_tm.tm_wday = (time+4) % 7;	// 01/01/1970 was a Thursday

	//---- start year calculation ----
	systime_tm.tm_year = 70;			// tm_year is "1900-based"
	n = 0x02;							// 1970 is 2 years after a leap year
	days = time;
	days_p_y = 365; 
	while(days >= days_p_y) {
		days -= days_p_y;
		systime_tm.tm_year++;
		n++;							// if (n%4) == 0 then leap year
		days_p_y = (n & 0x03) ? 365 : 366;
		}
	systime_tm.tm_yday = days;			// day of (this) year

	//---- start month/mday calculation ----
	days_u_m = &days_until_month[12];
	// if leap year then use 2nd half of table
	if((systime_tm.tm_year & 3) == 0) days_u_m += 12;
	n = 12;
	do {
		days_u_m--;
		n--;
		if(days >= *days_u_m) {
			systime_tm.tm_mday = days - *days_u_m + 1;
			systime_tm.tm_mon = n;
			n = 0;						// signal end of loop
			}
		} while(n);

	systime_tm.tm_isdst = 0;			// not used
    return(&systime_tm);
	}

//-----------------------------------------------------------------------------

// calculate timestamp from tm_year, tm_mon, tm_mday, tm_hour, tm_min, tm_sec
// caution: no input data check will be performed!
//
time_t mktime(struct tm *tmptr) {

	UINT16 year, leaps;
    time_t days, seconds;
	struct tm tmx;

	tmx = *tmptr;
    year = tmx.tm_year - 70;			// + 1900 - 1970
    leaps = (year + 2) / 4;
	if(((tmx.tm_year & 3) == 0) && (tmx.tm_mon < 2)) {
		leaps--;
		}
	days = days_until_month[tmx.tm_mon] + tmx.tm_mday - 1;
	tmx.tm_yday = days;
	days += year * (time_t)365L + leaps;
	tmx.tm_wday = days % 7 + 4;			// 01/01/1970 was a Thursday
    seconds = days * (time_t)86400L
		+ tmx.tm_hour * (time_t)3600L
		+ tmx.tm_min * (time_t)60L
		+ tmx.tm_sec;
    return seconds;
	}

//-----------------------------------------------------------------------------

#ifdef __USE_ASCTIME

// output format:
// Fri Nov 01 12:34:56 2002\n\0
// (all fields have fixed length)
//
UINT8 *asctime(struct tm *tmptr) {

	sprintf(systime_str, "%s %s %02d %02d:%02d:%02d %4d\n",
		wday_name[tmptr->tm_wday], month_name[tmptr->tm_mon],
		(UINT16)(tmptr->tm_mday), (UINT16)(tmptr->tm_hour),
		(UINT16)(tmptr->tm_min), (UINT16)(tmptr->tm_sec),
		(UINT16)(tmptr->tm_year + 1900));
	return systime_str;
	}

UINT8 *ctime(time_t *tptr) {

	return asctime(gmtime(tptr));
	}

#endif //__USE_ASCTIME

//=============================================================================