1/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
2/* This Source Code Form is subject to the terms of the Mozilla Public
3 * License, v. 2.0. If a copy of the MPL was not distributed with this
4 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
5
6/*
7 *----------------------------------------------------------------------
8 *
9 * prtime.h --
10 *
11 * NSPR date and time functions
12 *
13 *-----------------------------------------------------------------------
14 */
15
16#ifndef prtime_h___
17#define prtime_h___
18
19#include "prlong.h"
20
21PR_BEGIN_EXTERN_C
22
23/**********************************************************************/
24/************************* TYPES AND CONSTANTS ************************/
25/**********************************************************************/
26
27#define PR_MSEC_PER_SEC 1000L
28#define PR_USEC_PER_SEC 1000000L
29#define PR_NSEC_PER_SEC 1000000000L
30#define PR_USEC_PER_MSEC 1000L
31#define PR_NSEC_PER_MSEC 1000000L
32
33/*
34 * PRTime --
35 *
36 * NSPR represents basic time as 64-bit signed integers relative
37 * to midnight (00:00:00), January 1, 1970 Greenwich Mean Time (GMT).
38 * (GMT is also known as Coordinated Universal Time, UTC.)
39 * The units of time are in microseconds. Negative times are allowed
40 * to represent times prior to the January 1970 epoch. Such values are
41 * intended to be exported to other systems or converted to human
42 * readable form.
43 *
44 * Notes on porting: PRTime corresponds to time_t in ANSI C. NSPR 1.0
45 * simply uses PRInt64.
46 */
47
48typedef PRInt64 PRTime;
49
50/*
51 * Time zone and daylight saving time corrections applied to GMT to
52 * obtain the local time of some geographic location
53 */
54
55typedef struct PRTimeParameters {
56 PRInt32 tp_gmt_offset; /* the offset from GMT in seconds */
57 PRInt32 tp_dst_offset; /* contribution of DST in seconds */
58} PRTimeParameters;
59
60/*
61 * PRExplodedTime --
62 *
63 * Time broken down into human-readable components such as year, month,
64 * day, hour, minute, second, and microsecond. Time zone and daylight
65 * saving time corrections may be applied. If they are applied, the
66 * offsets from the GMT must be saved in the 'tm_params' field so that
67 * all the information is available to reconstruct GMT.
68 *
69 * Notes on porting: PRExplodedTime corrresponds to struct tm in
70 * ANSI C, with the following differences:
71 * - an additional field tm_usec;
72 * - replacing tm_isdst by tm_params;
73 * - the month field is spelled tm_month, not tm_mon;
74 * - we use absolute year, AD, not the year since 1900.
75 * The corresponding type in NSPR 1.0 is called PRTime. Below is
76 * a table of date/time type correspondence in the three APIs:
77 * API time since epoch time in components
78 * ANSI C time_t struct tm
79 * NSPR 1.0 PRInt64 PRTime
80 * NSPR 2.0 PRTime PRExplodedTime
81 */
82
83typedef struct PRExplodedTime {
84 PRInt32 tm_usec; /* microseconds past tm_sec (0-99999) */
85 PRInt32 tm_sec; /* seconds past tm_min (0-61, accomodating
86 up to two leap seconds) */
87 PRInt32 tm_min; /* minutes past tm_hour (0-59) */
88 PRInt32 tm_hour; /* hours past tm_day (0-23) */
89 PRInt32 tm_mday; /* days past tm_mon (1-31, note that it
90 starts from 1) */
91 PRInt32 tm_month; /* months past tm_year (0-11, Jan = 0) */
92 PRInt16 tm_year; /* absolute year, AD (note that we do not
93 count from 1900) */
94
95 PRInt8 tm_wday; /* calculated day of the week
96 (0-6, Sun = 0) */
97 PRInt16 tm_yday; /* calculated day of the year
98 (0-365, Jan 1 = 0) */
99
100 PRTimeParameters tm_params; /* time parameters used by conversion */
101} PRExplodedTime;
102
103/*
104 * PRTimeParamFn --
105 *
106 * A function of PRTimeParamFn type returns the time zone and
107 * daylight saving time corrections for some geographic location,
108 * given the current time in GMT. The input argument gmt should
109 * point to a PRExplodedTime that is in GMT, i.e., whose
110 * tm_params contains all 0's.
111 *
112 * For any time zone other than GMT, the computation is intended to
113 * consist of two steps:
114 * - Figure out the time zone correction, tp_gmt_offset. This number
115 * usually depends on the geographic location only. But it may
116 * also depend on the current time. For example, all of China
117 * is one time zone right now. But this situation may change
118 * in the future.
119 * - Figure out the daylight saving time correction, tp_dst_offset.
120 * This number depends on both the geographic location and the
121 * current time. Most of the DST rules are expressed in local
122 * current time. If so, one should apply the time zone correction
123 * to GMT before applying the DST rules.
124 */
125
126typedef PRTimeParameters (PR_CALLBACK *PRTimeParamFn)(const PRExplodedTime *gmt);
127
128/**********************************************************************/
129/****************************** FUNCTIONS *****************************/
130/**********************************************************************/
131
132/*
133 * The PR_Now routine returns the current time relative to the
134 * epoch, midnight, January 1, 1970 UTC. The units of the returned
135 * value are microseconds since the epoch.
136 *
137 * The values returned are not guaranteed to advance in a linear fashion
138 * due to the application of time correction protocols which synchronize
139 * computer clocks to some external time source. Consequently it should
140 * not be depended on for interval timing.
141 *
142 * The implementation is machine dependent.
143 * Cf. time_t time(time_t *tp) in ANSI C.
144 */
145NSPR_API(PRTime)
146PR_Now(void);
147
148/*
149 * Expand time binding it to time parameters provided by PRTimeParamFn.
150 * The calculation is envisoned to proceed in the following steps:
151 * - From given PRTime, calculate PRExplodedTime in GMT
152 * - Apply the given PRTimeParamFn to the GMT that we just calculated
153 * to obtain PRTimeParameters.
154 * - Add the PRTimeParameters offsets to GMT to get the local time
155 * as PRExplodedTime.
156 */
157
158NSPR_API(void) PR_ExplodeTime(
159 PRTime usecs, PRTimeParamFn params, PRExplodedTime *exploded);
160
161/* Reverse operation of PR_ExplodeTime */
162NSPR_API(PRTime)
163PR_ImplodeTime(const PRExplodedTime *exploded);
164
165/*
166 * Adjust exploded time to normalize field overflows after manipulation.
167 * Note that the following fields of PRExplodedTime should not be
168 * manipulated:
169 * - tm_month and tm_year: because the number of days in a month and
170 * number of days in a year are not constant, it is ambiguous to
171 * manipulate the month and year fields, although one may be tempted
172 * to. For example, what does "a month from January 31st" mean?
173 * - tm_wday and tm_yday: these fields are calculated by NSPR. Users
174 * should treat them as "read-only".
175 */
176
177NSPR_API(void) PR_NormalizeTime(
178 PRExplodedTime *exploded, PRTimeParamFn params);
179
180/**********************************************************************/
181/*********************** TIME PARAMETER FUNCTIONS *********************/
182/**********************************************************************/
183
184/* Time parameters that suit current host machine */
185NSPR_API(PRTimeParameters) PR_LocalTimeParameters(const PRExplodedTime *gmt);
186
187/* Time parameters that represent Greenwich Mean Time */
188NSPR_API(PRTimeParameters) PR_GMTParameters(const PRExplodedTime *gmt);
189
190/*
191 * Time parameters that represent the US Pacific Time Zone, with the
192 * current daylight saving time rules (for testing only)
193 */
194NSPR_API(PRTimeParameters) PR_USPacificTimeParameters(const PRExplodedTime *gmt);
195
196/*
197 * This parses a time/date string into a PRExplodedTime
198 * struct. It populates all fields but it can't split
199 * the offset from UTC into tp_gmt_offset and tp_dst_offset in
200 * most cases (exceptions: PST/PDT, MST/MDT, CST/CDT, EST/EDT, GMT/BST).
201 * In those cases tp_gmt_offset will be the sum of these two and
202 * tp_dst_offset will be 0.
203 * It returns PR_SUCCESS on success, and PR_FAILURE
204 * if the time/date string can't be parsed.
205 *
206 * Many formats are handled, including:
207 *
208 * 14 Apr 89 03:20:12
209 * 14 Apr 89 03:20 GMT
210 * Fri, 17 Mar 89 4:01:33
211 * Fri, 17 Mar 89 4:01 GMT
212 * Mon Jan 16 16:12 PDT 1989
213 * Mon Jan 16 16:12 +0130 1989
214 * 6 May 1992 16:41-JST (Wednesday)
215 * 22-AUG-1993 10:59:12.82
216 * 22-AUG-1993 10:59pm
217 * 22-AUG-1993 12:59am
218 * 22-AUG-1993 12:59 PM
219 * Friday, August 04, 1995 3:54 PM
220 * 06/21/95 04:24:34 PM
221 * 20/06/95 21:07
222 * 95-06-08 19:32:48 EDT
223 *
224 * If the input string doesn't contain a description of the timezone,
225 * we consult the `default_to_gmt' to decide whether the string should
226 * be interpreted relative to the local time zone (PR_FALSE) or GMT (PR_TRUE).
227 * The correct value for this argument depends on what standard specified
228 * the time string which you are parsing.
229 */
230
231NSPR_API(PRStatus) PR_ParseTimeStringToExplodedTime (
232 const char *string,
233 PRBool default_to_gmt,
234 PRExplodedTime *result);
235
236/*
237 * This uses PR_ParseTimeStringToExplodedTime to parse
238 * a time/date string and PR_ImplodeTime to transform it into
239 * a PRTime (microseconds after "1-Jan-1970 00:00:00 GMT").
240 * It returns PR_SUCCESS on success, and PR_FAILURE
241 * if the time/date string can't be parsed.
242 */
243
244NSPR_API(PRStatus) PR_ParseTimeString (
245 const char *string,
246 PRBool default_to_gmt,
247 PRTime *result);
248
249/* Format a time value into a buffer. Same semantics as strftime() */
250NSPR_API(PRUint32) PR_FormatTime(char *buf, int buflen, const char *fmt,
251 const PRExplodedTime *time);
252
253/* Format a time value into a buffer. Time is always in US English format,
254 * regardless of locale setting.
255 */
256NSPR_API(PRUint32)
257PR_FormatTimeUSEnglish(char *buf, PRUint32 bufSize,
258 const char *format, const PRExplodedTime *time);
259
260PR_END_EXTERN_C
261
262#endif /* prtime_h___ */
263

source code of include/nspr/prtime.h