/* * calc.c Calculations to work out what day it is etc for the Calendar * * Most of this stuff was taken from the gcal source by Thomas Esken. * * gcal is a text-based calendar program */ #include #include #include #include "calcs.h" #include #ifndef HAVE_STRCASECMP int strcasecmp(const char * /*s1*/, const char * /*s2*/); #endif /* Number of days in a month */ static const int dvec[] = { 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31}; /* Number of past days of a month */ static const int mvec[] = { 0, 31, 59, 90, 120, 151, 181, 212, 243, 273, 304, 334}; Greg_struct greg_reform_date[6] = { /* {int year, int month, int f_day, int l_day} */ { 1582, 10, 5, 14 }, { 1700, 2, 19, 28 }, { 1752, 9, 3, 13 }, { 1753, 2, 18, 28 }, /* must be left with all zeroes */ { 0,0,0,0 } }; Greg_struct *greg=greg_reform_date; /* * Computes the number of days in February and returns them, */ int days_of_february(const int year) { return((year&3) ? 28 : (!(year%100)&&(year%400)) ? 28 : 29); } int is_leap_year(const int year) { return (days_of_february(year) == 29); } /* * Check wether a given date is calid. */ int valid_date(const int day, const int month, const int year) { if ( day < 1 || month < MONTH_MIN || month > MONTH_MAX || ( (month != 2) && (day > dvec[month-1])) || ( (month == 2) && (day > days_of_february (year)))) return(FALSE); return(TRUE); } /* * Set a date back one day (to yesterday's date) */ void prev_date(int *day, int *month, int *year) { (*day)--; if ( !*day || !valid_date(*day, *month, *year)) { (*month)--; if (*month < MONTH_MIN) { *month = MONTH_MAX; (*year)--; } if (*month ==2) *day = days_of_february(*year); else *day = dvec[*month-1]; } } /* prev_date */ /* * Set a date forward one day (to tomorrow's date) */ void next_date(int *day, int *month, int *year) { (*day)++; if (!valid_date(*day, *month, *year)) { *day = DAY_MIN; if (*month == MONTH_MAX) { *month = MONTH_MIN; (*year)++; } else (*month)++; } } /* next_date */ /* * Get date from the system */ void get_system_date(int *day, int *month, int *year) { auto struct tm *sys_date; auto time_t sys_time; sys_time = time((time_t *)NULL); sys_date = localtime(&sys_time); *day = sys_date->tm_mday; *month = sys_date->tm_mon + 1; *year = sys_date->tm_year; if (*year < CENTURY) *year += CENTURY; } /* get_system_date */ /* * Given a string with the name of a month, return 1..12 or 0 if not found */ int month_atoi(const char *string) { int i; for (i = MONTH_MIN; i <= MONTH_MAX; i++) if (strcasecmp(string, (char *)get_month_name(i)) == 0) return i; return 0; } int day_atoi(const char *string) { int i; for (i = DAY_MIN; i <= DAY_MAX; i++) if (strcasecmp(string, (char *)get_day_name(i)) == 0) return i; return 0; } /* * Returns ordinal suffix (st, nd, rd, th) for a day */ const char *day_suffix(int day) { static const char *suffix[]={"th", "st", "nd", "rd"}; register int i; i = 0; if (day > 100) day %= 100; if (day < 11 || day > 13) i = day % 10; if (i > 3) i = 0; return(suffix[i]); } /* day_suffix */ /* * Returns the short name of the day of week, format "%-3s" */ const char *short3_day_name(const int day) { static const char *name[]={"invalid day", "Mon", "Tue", "Wed", "Thu", "Fri", "Sat", "Sun"}; return(((dayDAY_MAX)) ? name[0] : name[day]); } /* short3_day_name */ /* * Returns the short name of day of week */ const char *short_day_name(const int day) { static const char *name[]={"invalid day", "Mo", "Tu", "We", "Th", "Fr", "Sa", "Su"}; return(((dayDAY_MAX)) ? name[0] : name[day]); } /* short_day_name */ /* * Returns the complete name of the day */ const char *get_day_name(const int day) { static const char *name[]={"invalid day", "Monday", "Tuesday", "Wednesday", "Thursday", "Friday", "Saturday", "Sunday"}; return(((dayDAY_MAX)) ? name[0] : name[day]); } /* day_name */ /* * Returns the short name of the month */ const char *short_month_name(const int month) { static const char *name[]={ "invalid month", "Jan", "Feb", "Mar", "Apr", "May", "Jun", "Jul", "Aug", "Sep", "Oct", "Nov", "Dec"}; return(((monthMONTH_MAX)) ? name[0] : name[month]); } /* short_month_name() */ /* * Returns the name of the month */ const char *get_month_name(const int month) { static const char *name[]={ "invalid month", "January", "February", "March", "April", "May", "June", "July", "August", "September", "October", "November", "December"}; return(((monthMONTH_MAX)) ? name[0] : name[month]); } /* month_name() */ /* * Compute the absolute number of days of the given date since 1 Jan 0001 * respecting the missing period of the Gregorian Reformation * I am glad someone else worked this one out!! - cs */ unsigned long int date2num(const int day, const int month, const int year) { auto unsigned long int julian_days; julian_days = (unsigned long int)((year-1)*(unsigned long int)(DAY_LAST)+((year-1)>>2)); if (year > greg->year || ( (year == greg->year) && ( month > greg->month || ( (month == greg->month) && (day > greg->last_day))))) julian_days -= (unsigned long int)(greg->last_day - greg->first_day + 1); if (year > greg->year) { julian_days += (((year-1) / 400) - (greg->year / 400)); julian_days -= (((year-1) / 100) - (greg->year / 100)); if (!(greg->year % 100) && (greg->year % 400)) julian_days--; } julian_days += (unsigned long int)mvec[month-1]; julian_days += day; if ( (days_of_february(year) == 29) && (month > 2)) julian_days++; return(julian_days); } /* date2num */ /* * Computes the weekday of a Gregorian/Julian calendar date * (month must be 1..12) returns 1..7 (mo..su) */ int weekday_of_date(const int day, const int month, const int year) { auto unsigned long int julian_days=date2num(day, month,year)%DAY_MAX; return((julian_days>2) ? (int)julian_days-2 : (int)julian_days+5); } /* weekday_of_date() */