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date.h

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/*
** date.h
**
** libdate - A C library for manipulating dates
** Copyright (C) 2000 James Williams
**
** This library is free software; you can redistribute it and/or
** modify it under the terms of the GNU Lesser General Public
** License as published by the Free Software Foundation; either
** version 2 of the License, or (at your option) any later version.
**
** This library is distributed in the hope that it will be useful,
** but WITHOUT ANY WARRANTY; without even the implied warranty of
** MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
** Lesser General Public License for more details.
**
** You should have received a copy of the GNU Lesser General Public
** License along with this library; if not, write to the Free Software
** Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
**
*/

#ifndef DATE_H
#define DATE_H

#define DT_INTERVAL_DAY        1
#define DT_INTERVAL_MONTH      2
#define DT_INTERVAL_MONTH_DOW  3

#define DT_FIRST      1
#define DT_SECOND     2
#define DT_THIRD      3
#define DT_FOURTH     4
#define DT_LAST       5

#define DT_SUNDAY     0
#define DT_MONDAY     1
#define DT_TUESDAY    2
#define DT_WEDNESDAY  3
#define DT_THURSDAY   4
#define DT_FRIDAY     5
#define DT_SATURDAY   6
#define DT_DAY        10

#define DT_JANUARY    1
#define DT_FEBRUARY   2
#define DT_MARCH      3
#define DT_APRIL      4
#define DT_MAY        5
#define DT_JUNE       6
#define DT_JULY       7
#define DT_AUGUST     8
#define DT_SEPTEMBER  9
#define DT_OCTOBER    10
#define DT_NOVEMBER   11
#define DT_DECEMBER   12

/* For calculating the phase of the moon */
#define DT_LUNAR_PERIOD    29.5305882
#define DT_NEWMOON_OFFSET  17.7800836001

/* For ASCII output of dates */
#define DT_ASCII_BUFFER_SIZE  32
#define DT_NUMERIC_OUT        0x01
#define DT_US_FORMAT          0x02
#define DT_EUROPE_FORMAT      0x04
#define DT_UNIVERSAL_FORMAT   0x08

/* How to free an event structure */
#define DT_FREE_ALL           1
#define DT_FREE_NONE          2

/* Day of week adjustment sign modifiers */
#define DT_PREV              -1
#define DT_NONE               0
#define DT_NEXT               1

typedef struct
{
  long int rata_die;  
  int greg_calced;  
  int year;  
  int month;  
  int day;  
} DT_DATE;

typedef struct
{
  DT_DATE *start_date;  
  DT_DATE *end_date; 
  int interval_type; 
  int interval_length; 
  int event_length;  
  int ordinal; 
  int day; 
  int adj_rel; 
  int adj_sign; 
  int adj_dow; 
  char *pattern; 
  void *data;  
} DT_EVENT;

/* Macros */

#define DT_is_leap_year(x)  (DT_year(x)%400==0 \
                             || (DT_year(x)%100!=0 && DT_year(x)%4==0))

#define DT_is_leap_year_q(x)  ((x)%400==0 || ((x)%100!=0 && (x)%4==0))

#define DT_set_year(date,year)  DT_set_date((date),(year),DT_month(date), \
                                DT_day(date))

#define DT_set_month(date,month)  DT_set_date((date),DT_year(date), \
                                  (month), DT_day(date))

#define DT_set_day(date,day)  DT_set_date((date),DT_year(date), \
                              DT_month(date), (day))

DT_DATE *DT_mkdate(int year, int month, int day);
DT_DATE *DT_mkdate_dow(int ordinal, int dow, int month, int year);
DT_DATE *DT_mkdate_rata_die(long int rata_die);
void DT_rmdate(DT_DATE *date);
DT_DATE *DT_copy_date(DT_DATE *date);
long int DT_days_between(DT_DATE *date1, DT_DATE *date2);
long int DT_months_between(DT_DATE *date1, DT_DATE *date2);
char *DT_ascii(DT_DATE *date, unsigned long int format);
char *DT_ascii_r(char *buffer, int buf_size, DT_DATE *date,
                 unsigned long int format);
char *DT_dow_ascii(DT_DATE *date);
void DT_set_date(DT_DATE *date, int year, int month, int day);
void DT_set_rata_die(DT_DATE *date, long int rata_die);
int DT_dow(DT_DATE *date);
int DT_year(DT_DATE *date);
int DT_month(DT_DATE *date);
int DT_day(DT_DATE *date);
long int DT_rata_die(DT_DATE *date);
void DT_add_days(DT_DATE *date, long int days);
void DT_add_months(DT_DATE *date, long int months);
void DT_find_dow_date(DT_DATE *date, int ordinal, int dow, int month);
int DT_days_this_month(DT_DATE *date);
int DT_days_this_month_q(int year, int month);
void DT_easter(DT_DATE *date);

DT_EVENT *DT_mkevent(DT_DATE *start, DT_DATE *end, long int interval);
DT_EVENT *DT_mkevent_monthly(DT_DATE *start, DT_DATE *end,
                             long int interval, int day);
DT_EVENT *DT_mkevent_monthly_dow(DT_DATE *start, DT_DATE *end,
                                 long int interval, int ordinal, int dow);
void DT_rmevent(DT_EVENT *event, int freeall);
void DT_event_adj_rel(DT_EVENT *event, int adj);
void DT_event_adj_dow(DT_EVENT *event, int sign, int dow);
void DT_event_multiday(DT_EVENT *event, int len);
void DT_event_pattern(DT_EVENT *event, char *pattern);
int DT_is_event_today(DT_DATE *date, DT_EVENT *event);
DT_DATE *DT_event_next(DT_DATE *date, DT_EVENT *event);

int DT_cal_rows(DT_DATE *date);
int DT_cal_day_to_row(DT_DATE *date);
int DT_cal_day_to_col(DT_DATE *date);
int DT_cal_row_col_to_day(DT_DATE *date, int row, int col);

double DT_moon_age(DT_DATE *date, int timezone);
#endif  /* DATE_H */

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