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/gecko_api/include/prtime.h

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  1/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
  2/* ***** BEGIN LICENSE BLOCK *****
  3 * Version: MPL 1.1/GPL 2.0/LGPL 2.1
  4 *
  5 * The contents of this file are subject to the Mozilla Public License Version
  6 * 1.1 (the "License"); you may not use this file except in compliance with
  7 * the License. You may obtain a copy of the License at
  8 * http://www.mozilla.org/MPL/
  9 *
 10 * Software distributed under the License is distributed on an "AS IS" basis,
 11 * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
 12 * for the specific language governing rights and limitations under the
 13 * License.
 14 *
 15 * The Original Code is the Netscape Portable Runtime (NSPR).
 16 *
 17 * The Initial Developer of the Original Code is
 18 * Netscape Communications Corporation.
 19 * Portions created by the Initial Developer are Copyright (C) 1998-2000
 20 * the Initial Developer. All Rights Reserved.
 21 *
 22 * Contributor(s):
 23 *
 24 * Alternatively, the contents of this file may be used under the terms of
 25 * either the GNU General Public License Version 2 or later (the "GPL"), or
 26 * the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
 27 * in which case the provisions of the GPL or the LGPL are applicable instead
 28 * of those above. If you wish to allow use of your version of this file only
 29 * under the terms of either the GPL or the LGPL, and not to allow others to
 30 * use your version of this file under the terms of the MPL, indicate your
 31 * decision by deleting the provisions above and replace them with the notice
 32 * and other provisions required by the GPL or the LGPL. If you do not delete
 33 * the provisions above, a recipient may use your version of this file under
 34 * the terms of any one of the MPL, the GPL or the LGPL.
 35 *
 36 * ***** END LICENSE BLOCK ***** */
 37
 38/*
 39 *----------------------------------------------------------------------
 40 *
 41 * prtime.h --
 42 *
 43 *     NSPR date and time functions
 44 *
 45 *-----------------------------------------------------------------------
 46 */
 47
 48#ifndef prtime_h___
 49#define prtime_h___
 50
 51#include "prlong.h"
 52
 53PR_BEGIN_EXTERN_C
 54
 55/**********************************************************************/
 56/************************* TYPES AND CONSTANTS ************************/
 57/**********************************************************************/
 58
 59#define PR_MSEC_PER_SEC		1000UL
 60#define PR_USEC_PER_SEC		1000000UL
 61#define PR_NSEC_PER_SEC		1000000000UL
 62#define PR_USEC_PER_MSEC	1000UL
 63#define PR_NSEC_PER_MSEC	1000000UL
 64
 65/*
 66 * PRTime --
 67 *
 68 *     NSPR represents basic time as 64-bit signed integers relative
 69 *     to midnight (00:00:00), January 1, 1970 Greenwich Mean Time (GMT).
 70 *     (GMT is also known as Coordinated Universal Time, UTC.)
 71 *     The units of time are in microseconds. Negative times are allowed
 72 *     to represent times prior to the January 1970 epoch. Such values are
 73 *     intended to be exported to other systems or converted to human
 74 *     readable form.
 75 *
 76 *     Notes on porting: PRTime corresponds to time_t in ANSI C.  NSPR 1.0
 77 *     simply uses PRInt64.
 78 */
 79
 80typedef PRInt64 PRTime;
 81
 82/*
 83 * Time zone and daylight saving time corrections applied to GMT to
 84 * obtain the local time of some geographic location
 85 */
 86
 87typedef struct PRTimeParameters {
 88    PRInt32 tp_gmt_offset;     /* the offset from GMT in seconds */
 89    PRInt32 tp_dst_offset;     /* contribution of DST in seconds */
 90} PRTimeParameters;
 91
 92/*
 93 * PRExplodedTime --
 94 *
 95 *     Time broken down into human-readable components such as year, month,
 96 *     day, hour, minute, second, and microsecond.  Time zone and daylight
 97 *     saving time corrections may be applied.  If they are applied, the
 98 *     offsets from the GMT must be saved in the 'tm_params' field so that
 99 *     all the information is available to reconstruct GMT.
100 *
101 *     Notes on porting: PRExplodedTime corrresponds to struct tm in
102 *     ANSI C, with the following differences:
103 *       - an additional field tm_usec;
104 *       - replacing tm_isdst by tm_params;
105 *       - the month field is spelled tm_month, not tm_mon;
106 *       - we use absolute year, AD, not the year since 1900.
107 *     The corresponding type in NSPR 1.0 is called PRTime.  Below is
108 *     a table of date/time type correspondence in the three APIs:
109 *         API          time since epoch          time in components
110 *       ANSI C             time_t                  struct tm
111 *       NSPR 1.0           PRInt64                   PRTime
112 *       NSPR 2.0           PRTime                  PRExplodedTime
113 */
114
115typedef struct PRExplodedTime {
116    PRInt32 tm_usec;		    /* microseconds past tm_sec (0-99999)  */
117    PRInt32 tm_sec;             /* seconds past tm_min (0-61, accomodating
118                                   up to two leap seconds) */	
119    PRInt32 tm_min;             /* minutes past tm_hour (0-59) */
120    PRInt32 tm_hour;            /* hours past tm_day (0-23) */
121    PRInt32 tm_mday;            /* days past tm_mon (1-31, note that it
122				                starts from 1) */
123    PRInt32 tm_month;           /* months past tm_year (0-11, Jan = 0) */
124    PRInt16 tm_year;            /* absolute year, AD (note that we do not
125				                count from 1900) */
126
127    PRInt8 tm_wday;		        /* calculated day of the week
128				                (0-6, Sun = 0) */
129    PRInt16 tm_yday;            /* calculated day of the year 
130				                (0-365, Jan 1 = 0) */
131
132    PRTimeParameters tm_params;  /* time parameters used by conversion */
133} PRExplodedTime;
134
135/*
136 * PRTimeParamFn --
137 *
138 *     A function of PRTimeParamFn type returns the time zone and
139 *     daylight saving time corrections for some geographic location,
140 *     given the current time in GMT.  The input argument gmt should
141 *     point to a PRExplodedTime that is in GMT, i.e., whose
142 *     tm_params contains all 0's.
143 *
144 *     For any time zone other than GMT, the computation is intended to
145 *     consist of two steps:
146 *       - Figure out the time zone correction, tp_gmt_offset.  This number
147 *         usually depends on the geographic location only.  But it may
148 *         also depend on the current time.  For example, all of China
149 *         is one time zone right now.  But this situation may change
150 *         in the future.
151 *       - Figure out the daylight saving time correction, tp_dst_offset.
152 *         This number depends on both the geographic location and the
153 *         current time.  Most of the DST rules are expressed in local
154 *         current time.  If so, one should apply the time zone correction
155 *         to GMT before applying the DST rules.
156 */
157
158typedef PRTimeParameters (PR_CALLBACK *PRTimeParamFn)(const PRExplodedTime *gmt);
159
160/**********************************************************************/
161/****************************** FUNCTIONS *****************************/
162/**********************************************************************/
163
164/*
165 * The PR_Now routine returns the current time relative to the
166 * epoch, midnight, January 1, 1970 UTC. The units of the returned
167 * value are microseconds since the epoch.
168 *
169 * The values returned are not guaranteed to advance in a linear fashion
170 * due to the application of time correction protocols which synchronize
171 * computer clocks to some external time source. Consequently it should
172 * not be depended on for interval timing.
173 *
174 * The implementation is machine dependent.
175 * Cf. time_t time(time_t *tp) in ANSI C.
176 */
177#if defined(HAVE_WATCOM_BUG_2)
178PRTime __pascal __export __loadds
179#else
180NSPR_API(PRTime) 
181#endif
182PR_Now(void);
183
184/*
185 * Expand time binding it to time parameters provided by PRTimeParamFn.
186 * The calculation is envisoned to proceed in the following steps:
187 *   - From given PRTime, calculate PRExplodedTime in GMT
188 *   - Apply the given PRTimeParamFn to the GMT that we just calculated
189 *     to obtain PRTimeParameters.
190 *   - Add the PRTimeParameters offsets to GMT to get the local time
191 *     as PRExplodedTime.
192 */
193
194NSPR_API(void) PR_ExplodeTime(
195    PRTime usecs, PRTimeParamFn params, PRExplodedTime *exploded);
196
197/* Reverse operation of PR_ExplodeTime */
198#if defined(HAVE_WATCOM_BUG_2)
199PRTime __pascal __export __loadds
200#else
201NSPR_API(PRTime) 
202#endif
203PR_ImplodeTime(const PRExplodedTime *exploded);
204
205/*
206 * Adjust exploded time to normalize field overflows after manipulation.
207 * Note that the following fields of PRExplodedTime should not be
208 * manipulated:
209 *   - tm_month and tm_year: because the number of days in a month and
210 *     number of days in a year are not constant, it is ambiguous to
211 *     manipulate the month and year fields, although one may be tempted
212 *     to.  For example, what does "a month from January 31st" mean?
213 *   - tm_wday and tm_yday: these fields are calculated by NSPR.  Users
214 *     should treat them as "read-only".
215 */
216
217NSPR_API(void) PR_NormalizeTime(
218    PRExplodedTime *exploded, PRTimeParamFn params);
219
220/**********************************************************************/
221/*********************** TIME PARAMETER FUNCTIONS *********************/
222/**********************************************************************/
223
224/* Time parameters that suit current host machine */
225NSPR_API(PRTimeParameters) PR_LocalTimeParameters(const PRExplodedTime *gmt);
226
227/* Time parameters that represent Greenwich Mean Time */
228NSPR_API(PRTimeParameters) PR_GMTParameters(const PRExplodedTime *gmt);
229
230/*
231 * Time parameters that represent the US Pacific Time Zone, with the
232 * current daylight saving time rules (for testing only)
233 */
234NSPR_API(PRTimeParameters) PR_USPacificTimeParameters(const PRExplodedTime *gmt);
235
236/*
237 * This parses a time/date string into a PRExplodedTime
238 * struct. It populates all fields but it can't split
239 * the offset from UTC into tp_gmt_offset and tp_dst_offset in
240 * most cases (exceptions: PST/PDT, MST/MDT, CST/CDT, EST/EDT, GMT/BST).
241 * In those cases tp_gmt_offset will be the sum of these two and
242 * tp_dst_offset will be 0.
243 * It returns PR_SUCCESS on success, and PR_FAILURE
244 * if the time/date string can't be parsed.
245 *
246 * Many formats are handled, including:
247 *
248 *   14 Apr 89 03:20:12
249 *   14 Apr 89 03:20 GMT
250 *   Fri, 17 Mar 89 4:01:33
251 *   Fri, 17 Mar 89 4:01 GMT
252 *   Mon Jan 16 16:12 PDT 1989
253 *   Mon Jan 16 16:12 +0130 1989
254 *   6 May 1992 16:41-JST (Wednesday)
255 *   22-AUG-1993 10:59:12.82
256 *   22-AUG-1993 10:59pm
257 *   22-AUG-1993 12:59am
258 *   22-AUG-1993 12:59 PM
259 *   Friday, August 04, 1995 3:54 PM
260 *   06/21/95 04:24:34 PM
261 *   20/06/95 21:07
262 *   95-06-08 19:32:48 EDT
263 *
264 * If the input string doesn't contain a description of the timezone,
265 * we consult the `default_to_gmt' to decide whether the string should
266 * be interpreted relative to the local time zone (PR_FALSE) or GMT (PR_TRUE).
267 * The correct value for this argument depends on what standard specified
268 * the time string which you are parsing.
269 */
270
271NSPR_API(PRStatus) PR_ParseTimeStringToExplodedTime (
272        const char *string,
273        PRBool default_to_gmt,
274        PRExplodedTime *result);
275
276/*
277 * This uses PR_ParseTimeStringToExplodedTime to parse
278 * a time/date string and PR_ImplodeTime to transform it into
279 * a PRTime (microseconds after "1-Jan-1970 00:00:00 GMT").
280 * It returns PR_SUCCESS on success, and PR_FAILURE
281 * if the time/date string can't be parsed.
282 */
283
284NSPR_API(PRStatus) PR_ParseTimeString (
285	const char *string,
286	PRBool default_to_gmt,
287	PRTime *result);
288
289/*
290 * FIXME: should we also have a formatting function, such as asctime, ctime,
291 * and strftime in standard C library?  But this would involve
292 * internationalization issues.  Might want to provide a US English version.
293 */
294
295/**********************************************************************/
296/*********************** OLD COMPATIBILITYFUNCTIONS *******************/
297/**********************************************************************/
298#ifndef NO_NSPR_10_SUPPORT
299
300/* Format a time value into a buffer. Same semantics as strftime() */
301NSPR_API(PRUint32) PR_FormatTime(char *buf, int buflen, const char *fmt, 
302                                           const PRExplodedTime *tm);
303
304/* Format a time value into a buffer. Time is always in US English format, regardless
305 * of locale setting.
306 */
307NSPR_API(PRUint32)
308PR_FormatTimeUSEnglish( char* buf, PRUint32 bufSize,
309                        const char* format, const PRExplodedTime* tm );
310
311#endif /* NO_NSPR_10_SUPPORT */
312
313PR_END_EXTERN_C
314
315#endif /* prtime_h___ */