libc/tzcode/tzfile.h

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

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

#ifndef TZDIR
#define TZDIR "/system/usr/share/zoneinfo" /* Time zone object file directory */
#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 */