tzfile.h

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#ifndef TZFILE_H

#define TZFILE_H

/*
** This file is in the public domain, so clarified as of
** 1996-06-05 by Arthur David Olson.
*/

/*
** This header is for use ONLY with the time conversion code.
** There is no guarantee that it will remain unchanged,
** or that it will remain at all.
** Do NOT copy it to any system include directory.
** Thank you!
*/

/*
** ID
*/

#ifndef lint
#ifndef NOID
static char __attribute__((unused)) tzfilehid[] = "@(#)tzfile.h   8.1";
#endif /* !defined NOID */
#endif /* !defined lint */

/*
** Information about time zone files.
*/

#ifndef TZDIR
#ifdef SOLARIS
#define TZDIR  "/usr/share/lib/zoneinfo"
#else
#define TZDIR  "/usr/share/zoneinfo"
#endif /* defined SOLARIS */
#endif /* !defined TZDIR */

#ifndef TZDEFAULT
#define TZDEFAULT "localtime"
#endif /* !defined TZDEFAULT */

#ifndef TZDEFRULES
#define TZDEFRULES   "posixrules"
#endif /* !defined TZDEFRULES */

/*
** Each file begins with. . .
*/

#define  TZ_MAGIC "TZif"

struct tzhead {
   char  tzh_magic[4];     /* TZ_MAGIC */
   char  tzh_version[1];      /* '\0' or '2' as of 2005 */
   char  tzh_reserved[15]; /* reserved--must be zero */
   char  tzh_ttisgmtcnt[4];   /* coded number of trans. time flags */
   char  tzh_ttisstdcnt[4];   /* coded number of trans. time flags */
   char  tzh_leapcnt[4];      /* coded number of leap seconds */
   char  tzh_timecnt[4];      /* coded number of transition times */
   char  tzh_typecnt[4];      /* coded number of local time types */
   char  tzh_charcnt[4];      /* coded number of abbr. chars */
};

/*
** . . .followed by. . .
**
** tzh_timecnt (char [4])s    coded transition times a la time(2)
** tzh_timecnt (unsigned char)s  types of local time starting at above
** tzh_typecnt repetitions of
**    one (char [4])    coded UTC offset in seconds
**    one (unsigned char)  used to set tm_isdst
**    one (unsigned char)  that's an abbreviation list index
** tzh_charcnt (char)s     '\0'-terminated zone abbreviations
** tzh_leapcnt repetitions of
**    one (char [4])    coded leap second transition times
**    one (char [4])    total correction after above
** tzh_ttisstdcnt (char)s     indexed by type; if TRUE, transition
**             time is standard time, if FALSE,
**             transition time is wall clock time
**             if absent, transition times are
**             assumed to be wall clock time
** tzh_ttisgmtcnt (char)s     indexed by type; if TRUE, transition
**             time is UTC, if FALSE,
**             transition time is local time
**             if absent, transition times are
**             assumed to be local time
*/

/*
** If tzh_version is '2' or greater, the above is followed by a second instance
** of tzhead and a second instance of the data in which each coded transition
** time uses 8 rather than 4 chars,
** then a POSIX-TZ-environment-variable-style string for use in handling
** instants after the last transition time stored in the file
** (with nothing between the newlines if there is no POSIX representation for
** such instants).
*/

/*
** In the current implementation, "tzset()" refuses to deal with files that
** exceed any of the limits below.
*/

#ifndef TZ_MAX_TIMES
#define TZ_MAX_TIMES 1200
#endif /* !defined TZ_MAX_TIMES */

#ifndef TZ_MAX_TYPES
#ifndef NOSOLAR
#define TZ_MAX_TYPES 256 /* Limited by what (unsigned char)'s can hold */
#endif /* !defined NOSOLAR */
#ifdef NOSOLAR
/*
** Must be at least 14 for Europe/Riga as of Jan 12 1995,
** as noted by Earl Chew.
*/
#define TZ_MAX_TYPES 20 /* Maximum number of local time types */
#endif /* !defined NOSOLAR */
#endif /* !defined TZ_MAX_TYPES */

#ifndef TZ_MAX_CHARS
#define TZ_MAX_CHARS 50 /* Maximum number of abbreviation characters */
            /* (limited by what unsigned chars can hold) */
#endif /* !defined TZ_MAX_CHARS */

#ifndef TZ_MAX_LEAPS
#define TZ_MAX_LEAPS 50 /* Maximum number of leap second corrections */
#endif /* !defined TZ_MAX_LEAPS */

#define SECSPERMIN   60
#define MINSPERHOUR  60
#define HOURSPERDAY  24
#define DAYSPERWEEK  7
#define DAYSPERNYEAR 365
#define DAYSPERLYEAR 366
#define SECSPERHOUR  (SECSPERMIN * MINSPERHOUR)
#define SECSPERDAY   ((long) SECSPERHOUR * HOURSPERDAY)
#define MONSPERYEAR  12

#define TM_SUNDAY 0
#define TM_MONDAY 1
#define TM_TUESDAY   2
#define TM_WEDNESDAY 3
#define TM_THURSDAY  4
#define TM_FRIDAY 5
#define TM_SATURDAY  6

#define TM_JANUARY   0
#define TM_FEBRUARY  1
#define TM_MARCH  2
#define TM_APRIL  3
#define TM_MAY    4
#define TM_JUNE      5
#define TM_JULY      6
#define TM_AUGUST 7
#define TM_SEPTEMBER 8
#define TM_OCTOBER   9
#define TM_NOVEMBER  10
#define TM_DECEMBER  11

#define TM_YEAR_BASE 1900

#define EPOCH_YEAR   1970
#define EPOCH_WDAY   TM_THURSDAY

#define isleap(y) (((y) % 4) == 0 && (((y) % 100) != 0 || ((y) % 400) == 0))

/*
** Since everything in isleap is modulo 400 (or a factor of 400), we know that
** isleap(y) == isleap(y % 400)
** and so
** isleap(a + b) == isleap((a + b) % 400)
** or
** isleap(a + b) == isleap(a % 400 + b % 400)
** This is true even if % means modulo rather than Fortran remainder
** (which is allowed by C89 but not C99).
** We use this to avoid addition overflow problems.
*/

#define isleap_sum(a, b)   isleap((a) % 400 + (b) % 400)

#endif /* !defined TZFILE_H */