GRASS GIS 8 Programmer's Manual 8.2.0(2022)-exported
tz2.c
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1/*
2 * Copyright (C) 1995. Bill Brown <brown@gis.uiuc.edu> & Michael Shapiro
3 *
4 * This program is free software under the GPL (>=v2)
5 * Read the file GPL.TXT coming with GRASS for details.
6 */
7#include <grass/datetime.h>
8
9
10/*!
11 * \brief
12 *
13 * if dt has a timezone, increment dt by minutes-dt.tz MINUTES and set dt.tz = minutes
14 * Returns:
15 * 0 OK
16 * <b>datetime_check_timezone</b> (dt) if not
17 * -4 if minutes invalid
18 *
19 * \param dt
20 * \param minutes
21 * \return int
22 */
23
24int datetime_change_timezone(DateTime * dt, int minutes)
25{ /* new timezone in minutes */
26 int stat;
27 int old_minutes, diff_minutes;
28 DateTime incr;
29
30 stat = datetime_get_timezone(dt, &old_minutes);
31 if (stat != 0)
32 return stat;
33 if (!datetime_is_valid_timezone(minutes))
34 return datetime_error(-4, "invalid datetime timezone");
35
36 /* create a relative minute increment */
37 datetime_set_type(&incr, DATETIME_RELATIVE, DATETIME_MINUTE,
38 DATETIME_MINUTE, 0);
39
40 /* BB - needed to set SIGN here */
41 diff_minutes = minutes - old_minutes;
42 if (diff_minutes >= 0) {
43 datetime_set_minute(&incr, diff_minutes);
44 }
45 else {
47 datetime_set_minute(&incr, -diff_minutes);
48 }
49
50 return datetime_increment(dt, &incr);
51}
52
53
54/*!
55 * \brief
56 *
57 * Return <b>datetime_change_timezone</b> (dt, 0);
58 *
59 * \param dt
60 * \return int
61 */
62
63int datetime_change_to_utc(DateTime * dt)
64{
65 return datetime_change_timezone(dt, 0);
66}
67
68
69/*!
70 * \brief
71 *
72 * tz = abs(tz)
73 * *hour = tz/60
74 * *minute = tz%60
75 * Note: hour,minute are non-negative. Must look at sign of tz itself to see if
76 * the tz is negative offset or not. This routine would be used to format tz for
77 * output. For example if tz=-350 this would be hour=5 minute=50, but negative.
78 * Output might encode this as -0550: printf ("%s%02d%02d", tz<0?"-":"",
79 * hour, minute)
80 *
81 * \param tz
82 * \param hours
83 * \param minutes
84 * \return void
85 */
86
87void datetime_decompose_timezone(int tz, int *hours, int *minutes)
88{
89 if (tz < 0)
90 tz = -tz;
91
92 *hours = tz / 60;
93 *minutes = tz % 60;
94}
int datetime_error(int code, char *msg)
record 'code' and 'msg' as error code/msg (in static variables) code==0 will clear the error (ie set ...
int datetime_increment(DateTime *src, DateTime *incr)
This function changes the 'src' date/time data based on the 'incr' The type (mode/from/to) of the '...
Definition: incr1.c:67
void datetime_invert_sign(DateTime *dt)
Definition: sign.c:80
int datetime_set_type(DateTime *dt, int mode, int from, int to, int fracsec)
Definition: type.c:37
int datetime_is_valid_timezone(int minutes)
Returns: 1 OK: -720 <= minutes <= 780 (720 = 12 hours; 780 = 13 hours) 0 NOT OK.
Definition: tz1.c:111
int datetime_get_timezone(const DateTime *dt, int *minutes)
returns 0 on success
Definition: tz1.c:49
int datetime_change_to_utc(DateTime *dt)
Return datetime_change_timezone (dt, 0);.
Definition: tz2.c:63
int datetime_change_timezone(DateTime *dt, int minutes)
if dt has a timezone, increment dt by minutes-dt.tz MINUTES and set dt.tz = minutes Returns: 0 OK ...
Definition: tz2.c:24
void datetime_decompose_timezone(int tz, int *hours, int *minutes)
tz = abs(tz) *hour = tz/60 *minute = tz%60 Note: hour,minute are non-negative....
Definition: tz2.c:87
int datetime_set_minute(DateTime *dt, int minute)
returns 0 on success or negative value on error
Definition: values.c:442