From 2485eae90d07f5d649729e6bd02d15ae1b38006d Mon Sep 17 00:00:00 2001 From: Craig Small Date: Mon, 12 Jan 1998 02:51:30 +0000 Subject: New Gnome Calendar files svn path=/trunk/; revision=2 --- calendar/calcs.c | 273 +++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 273 insertions(+) create mode 100644 calendar/calcs.c (limited to 'calendar/calcs.c') diff --git a/calendar/calcs.c b/calendar/calcs.c new file mode 100644 index 0000000000..002ffbf28b --- /dev/null +++ b/calendar/calcs.c @@ -0,0 +1,273 @@ +/* + * 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" + +/* 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, j; + int len; + char *ptr; + + len = strlen(string); + + for(i= MONTH_MIN; i <= MONTH_MAX; i++) { + ptr = (char*)month_name(i); + j = 0; + while ( *(ptr + j) && string[j]) + if (tolower((ptr+j)) == tolower(string[j])) + j++; + else + break; + if (j == len || !*(ptr + j)) + return(i); + } + return 0; +} /* month_atoi */ + +int day_atoi(const char *string) +{ + int i, j; + int len; + char *ptr; + + len = strlen(string); + + for(i= DAY_MIN; i <= DAY_MAX; i++) { + ptr = (char*)day_name(i); + j = 0; + while ( *(ptr + j) && string[j]) + if (tolower((ptr+j)) == tolower(string[j])) + j++; + else + break; + if (j == len || !*(ptr + j)) + return(i); + } + return 0; +} /* day_atoi */ + +/* + * 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 *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 *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() */ + -- cgit v1.2.3