5 * This file is in the public domain, so clarified as of
6 * 1996-06-05 by Arthur David Olson.
9 * $PostgreSQL: pgsql/src/timezone/tzfile.h,v 1.8 2009/06/11 14:49:15 momjian Exp $
13 * This header is for use ONLY with the time conversion code.
14 * There is no guarantee that it will remain unchanged,
15 * or that it will remain at all.
16 * Do NOT copy it to any system include directory.
21 * Information about time zone files.
24 #define TZDEFAULT "localtime"
25 #define TZDEFRULES "posixrules"
28 * Each file begins with. . .
31 #define TZ_MAGIC "TZif"
35 char tzh_magic[4]; /* TZ_MAGIC */
36 char tzh_version[1]; /* '\0' or '2' as of 2005 */
37 char tzh_reserved[15]; /* reserved--must be zero */
38 char tzh_ttisgmtcnt[4]; /* coded number of trans. time flags */
39 char tzh_ttisstdcnt[4]; /* coded number of trans. time flags */
40 char tzh_leapcnt[4]; /* coded number of leap seconds */
41 char tzh_timecnt[4]; /* coded number of transition times */
42 char tzh_typecnt[4]; /* coded number of local time types */
43 char tzh_charcnt[4]; /* coded number of abbr. chars */
47 * . . .followed by. . .
49 * tzh_timecnt (char [4])s coded transition times a la time(2)
50 * tzh_timecnt (unsigned char)s types of local time starting at above
51 * tzh_typecnt repetitions of
52 * one (char [4]) coded UTC offset in seconds
53 * one (unsigned char) used to set tm_isdst
54 * one (unsigned char) that's an abbreviation list index
55 * tzh_charcnt (char)s '\0'-terminated zone abbreviations
56 * tzh_leapcnt repetitions of
57 * one (char [4]) coded leap second transition times
58 * one (char [4]) total correction after above
59 * tzh_ttisstdcnt (char)s indexed by type; if TRUE, transition
60 * time is standard time, if FALSE,
61 * transition time is wall clock time
62 * if absent, transition times are
63 * assumed to be wall clock time
64 * tzh_ttisgmtcnt (char)s indexed by type; if TRUE, transition
65 * time is UTC, if FALSE,
66 * transition time is local time
67 * if absent, transition times are
68 * assumed to be local time
73 * If tzh_version is '2' or greater, the above is followed by a second instance
74 * of tzhead and a second instance of the data in which each coded transition
75 * time uses 8 rather than 4 chars,
76 * then a POSIX-TZ-environment-variable-style string for use in handling
77 * instants after the last transition time stored in the file
78 * (with nothing between the newlines if there is no POSIX representation for
83 * In the current implementation, "tzset()" refuses to deal with files that
84 * exceed any of the limits below.
87 #define TZ_MAX_TIMES 1200
89 #define TZ_MAX_TYPES 256 /* Limited by what (unsigned char)'s can hold */
91 #define TZ_MAX_CHARS 50 /* Maximum number of abbreviation characters */
92 /* (limited by what unsigned chars can hold) */
94 #define TZ_MAX_LEAPS 50 /* Maximum number of leap second corrections */
97 #define MINSPERHOUR 60
98 #define HOURSPERDAY 24
100 #define DAYSPERNYEAR 365
101 #define DAYSPERLYEAR 366
102 #define SECSPERHOUR (SECSPERMIN * MINSPERHOUR)
103 #define SECSPERDAY ((long) SECSPERHOUR * HOURSPERDAY)
104 #define MONSPERYEAR 12
109 #define TM_WEDNESDAY 3
110 #define TM_THURSDAY 4
112 #define TM_SATURDAY 6
115 #define TM_FEBRUARY 1
122 #define TM_SEPTEMBER 8
124 #define TM_NOVEMBER 10
125 #define TM_DECEMBER 11
127 #define TM_YEAR_BASE 1900
129 #define EPOCH_YEAR 1970
130 #define EPOCH_WDAY TM_THURSDAY
132 #define isleap(y) (((y) % 4) == 0 && (((y) % 100) != 0 || ((y) % 400) == 0))
135 * Since everything in isleap is modulo 400 (or a factor of 400), we know that
136 * isleap(y) == isleap(y % 400)
138 * isleap(a + b) == isleap((a + b) % 400)
140 * isleap(a + b) == isleap(a % 400 + b % 400)
141 * This is true even if % means modulo rather than Fortran remainder
142 * (which is allowed by C89 but not C99).
143 * We use this to avoid addition overflow problems.
146 #define isleap_sum(a, b) isleap((a) % 400 + (b) % 400)
148 #endif /* !defined TZFILE_H */