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gecko-sdk/include/prtime.h

+/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* ***** BEGIN LICENSE BLOCK *****
+ * Version: MPL 1.1/GPL 2.0/LGPL 2.1
+ *
+ * The contents of this file are subject to the Mozilla Public License Version
+ * 1.1 (the "License"); you may not use this file except in compliance with
+ * the License. You may obtain a copy of the License at
+ * http://www.mozilla.org/MPL/
+ *
+ * Software distributed under the License is distributed on an "AS IS" basis,
+ * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
+ * for the specific language governing rights and limitations under the
+ * License.
+ *
+ * The Original Code is the Netscape Portable Runtime (NSPR).
+ *
+ * The Initial Developer of the Original Code is
+ * Netscape Communications Corporation.
+ * Portions created by the Initial Developer are Copyright (C) 1998-2000
+ * the Initial Developer. All Rights Reserved.
+ *
+ * Contributor(s):
+ *
+ * Alternatively, the contents of this file may be used under the terms of
+ * either the GNU General Public License Version 2 or later (the "GPL"), or
+ * the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
+ * in which case the provisions of the GPL or the LGPL are applicable instead
+ * of those above. If you wish to allow use of your version of this file only
+ * under the terms of either the GPL or the LGPL, and not to allow others to
+ * use your version of this file under the terms of the MPL, indicate your
+ * decision by deleting the provisions above and replace them with the notice
+ * and other provisions required by the GPL or the LGPL. If you do not delete
+ * the provisions above, a recipient may use your version of this file under
+ * the terms of any one of the MPL, the GPL or the LGPL.
+ *
+ * ***** END LICENSE BLOCK ***** */
+
+/*
+ *----------------------------------------------------------------------
+ *
+ * prtime.h --
+ *
+ *     NSPR date and time functions
+ *
+ *-----------------------------------------------------------------------
+ */
+
+#ifndef prtime_h___
+#define prtime_h___
+
+#include "prlong.h"
+
+PR_BEGIN_EXTERN_C
+
+/**********************************************************************/
+/************************* TYPES AND CONSTANTS ************************/
+/**********************************************************************/
+
+#define PR_MSEC_PER_SEC         1000UL
+#define PR_USEC_PER_SEC         1000000UL
+#define PR_NSEC_PER_SEC         1000000000UL
+#define PR_USEC_PER_MSEC        1000UL
+#define PR_NSEC_PER_MSEC        1000000UL
+
+/*
+ * PRTime --
+ *
+ *     NSPR represents basic time as 64-bit signed integers relative
+ *     to midnight (00:00:00), January 1, 1970 Greenwich Mean Time (GMT).
+ *     (GMT is also known as Coordinated Universal Time, UTC.)
+ *     The units of time are in microseconds. Negative times are allowed
+ *     to represent times prior to the January 1970 epoch. Such values are
+ *     intended to be exported to other systems or converted to human
+ *     readable form.
+ *
+ *     Notes on porting: PRTime corresponds to time_t in ANSI C.  NSPR 1.0
+ *     simply uses PRInt64.
+ */
+
+typedef PRInt64 PRTime;
+
+/*
+ * Time zone and daylight saving time corrections applied to GMT to
+ * obtain the local time of some geographic location
+ */
+
+typedef struct PRTimeParameters {
+    PRInt32 tp_gmt_offset;     /* the offset from GMT in seconds */
+    PRInt32 tp_dst_offset;     /* contribution of DST in seconds */
+} PRTimeParameters;
+
+/*
+ * PRExplodedTime --
+ *
+ *     Time broken down into human-readable components such as year, month,
+ *     day, hour, minute, second, and microsecond.  Time zone and daylight
+ *     saving time corrections may be applied.  If they are applied, the
+ *     offsets from the GMT must be saved in the 'tm_params' field so that
+ *     all the information is available to reconstruct GMT.
+ *
+ *     Notes on porting: PRExplodedTime corrresponds to struct tm in
+ *     ANSI C, with the following differences:
+ *       - an additional field tm_usec;
+ *       - replacing tm_isdst by tm_params;
+ *       - the month field is spelled tm_month, not tm_mon;
+ *       - we use absolute year, AD, not the year since 1900.
+ *     The corresponding type in NSPR 1.0 is called PRTime.  Below is
+ *     a table of date/time type correspondence in the three APIs:
+ *         API          time since epoch          time in components
+ *       ANSI C             time_t                  struct tm
+ *       NSPR 1.0           PRInt64                   PRTime
+ *       NSPR 2.0           PRTime                  PRExplodedTime
+ */
+
+typedef struct PRExplodedTime {
+    PRInt32 tm_usec;                /* microseconds past tm_sec (0-99999)  */
+    PRInt32 tm_sec;             /* seconds past tm_min (0-61, accomodating
+                                   up to two leap seconds) */   
+    PRInt32 tm_min;             /* minutes past tm_hour (0-59) */
+    PRInt32 tm_hour;            /* hours past tm_day (0-23) */
+    PRInt32 tm_mday;            /* days past tm_mon (1-31, note that it
+                                                starts from 1) */
+    PRInt32 tm_month;           /* months past tm_year (0-11, Jan = 0) */
+    PRInt16 tm_year;            /* absolute year, AD (note that we do not
+                                                count from 1900) */
+
+    PRInt8 tm_wday;                     /* calculated day of the week
+                                                (0-6, Sun = 0) */
+    PRInt16 tm_yday;            /* calculated day of the year 
+                                                (0-365, Jan 1 = 0) */
+
+    PRTimeParameters tm_params;  /* time parameters used by conversion */
+} PRExplodedTime;
+
+/*
+ * PRTimeParamFn --
+ *
+ *     A function of PRTimeParamFn type returns the time zone and
+ *     daylight saving time corrections for some geographic location,
+ *     given the current time in GMT.  The input argument gmt should
+ *     point to a PRExplodedTime that is in GMT, i.e., whose
+ *     tm_params contains all 0's.
+ *
+ *     For any time zone other than GMT, the computation is intended to
+ *     consist of two steps:
+ *       - Figure out the time zone correction, tp_gmt_offset.  This number
+ *         usually depends on the geographic location only.  But it may
+ *         also depend on the current time.  For example, all of China
+ *         is one time zone right now.  But this situation may change
+ *         in the future.
+ *       - Figure out the daylight saving time correction, tp_dst_offset.
+ *         This number depends on both the geographic location and the
+ *         current time.  Most of the DST rules are expressed in local
+ *         current time.  If so, one should apply the time zone correction
+ *         to GMT before applying the DST rules.
+ */
+
+typedef PRTimeParameters (PR_CALLBACK *PRTimeParamFn)(const PRExplodedTime *gmt);
+
+/**********************************************************************/
+/****************************** FUNCTIONS *****************************/
+/**********************************************************************/
+
+/*
+ * The PR_Now routine returns the current time relative to the
+ * epoch, midnight, January 1, 1970 UTC. The units of the returned
+ * value are microseconds since the epoch.
+ *
+ * The values returned are not guaranteed to advance in a linear fashion
+ * due to the application of time correction protocols which synchronize
+ * computer clocks to some external time source. Consequently it should
+ * not be depended on for interval timing.
+ *
+ * The implementation is machine dependent.
+ * Cf. time_t time(time_t *tp) in ANSI C.
+ */
+#if defined(HAVE_WATCOM_BUG_2)
+PRTime __pascal __export __loadds
+#else
+NSPR_API(PRTime) 
+#endif
+PR_Now(void);
+
+/*
+ * Expand time binding it to time parameters provided by PRTimeParamFn.
+ * The calculation is envisoned to proceed in the following steps:
+ *   - From given PRTime, calculate PRExplodedTime in GMT
+ *   - Apply the given PRTimeParamFn to the GMT that we just calculated
+ *     to obtain PRTimeParameters.
+ *   - Add the PRTimeParameters offsets to GMT to get the local time
+ *     as PRExplodedTime.
+ */
+
+NSPR_API(void) PR_ExplodeTime(
+    PRTime usecs, PRTimeParamFn params, PRExplodedTime *exploded);
+
+/* Reverse operation of PR_ExplodeTime */
+#if defined(HAVE_WATCOM_BUG_2)
+PRTime __pascal __export __loadds
+#else
+NSPR_API(PRTime) 
+#endif
+PR_ImplodeTime(const PRExplodedTime *exploded);
+
+/*
+ * Adjust exploded time to normalize field overflows after manipulation.
+ * Note that the following fields of PRExplodedTime should not be
+ * manipulated:
+ *   - tm_month and tm_year: because the number of days in a month and
+ *     number of days in a year are not constant, it is ambiguous to
+ *     manipulate the month and year fields, although one may be tempted
+ *     to.  For example, what does "a month from January 31st" mean?
+ *   - tm_wday and tm_yday: these fields are calculated by NSPR.  Users
+ *     should treat them as "read-only".
+ */
+
+NSPR_API(void) PR_NormalizeTime(
+    PRExplodedTime *exploded, PRTimeParamFn params);
+
+/**********************************************************************/
+/*********************** TIME PARAMETER FUNCTIONS *********************/
+/**********************************************************************/
+
+/* Time parameters that suit current host machine */
+NSPR_API(PRTimeParameters) PR_LocalTimeParameters(const PRExplodedTime *gmt);
+
+/* Time parameters that represent Greenwich Mean Time */
+NSPR_API(PRTimeParameters) PR_GMTParameters(const PRExplodedTime *gmt);
+
+/*
+ * Time parameters that represent the US Pacific Time Zone, with the
+ * current daylight saving time rules (for testing only)
+ */
+NSPR_API(PRTimeParameters) PR_USPacificTimeParameters(const PRExplodedTime *gmt);
+
+/*
+ * This parses a time/date string into a PRTime
+ * (microseconds after "1-Jan-1970 00:00:00 GMT").
+ * It returns PR_SUCCESS on success, and PR_FAILURE
+ * if the time/date string can't be parsed.
+ *
+ * Many formats are handled, including:
+ *
+ *   14 Apr 89 03:20:12
+ *   14 Apr 89 03:20 GMT
+ *   Fri, 17 Mar 89 4:01:33
+ *   Fri, 17 Mar 89 4:01 GMT
+ *   Mon Jan 16 16:12 PDT 1989
+ *   Mon Jan 16 16:12 +0130 1989
+ *   6 May 1992 16:41-JST (Wednesday)
+ *   22-AUG-1993 10:59:12.82
+ *   22-AUG-1993 10:59pm
+ *   22-AUG-1993 12:59am
+ *   22-AUG-1993 12:59 PM
+ *   Friday, August 04, 1995 3:54 PM
+ *   06/21/95 04:24:34 PM
+ *   20/06/95 21:07
+ *   95-06-08 19:32:48 EDT
+ *
+ * If the input string doesn't contain a description of the timezone,
+ * we consult the `default_to_gmt' to decide whether the string should
+ * be interpreted relative to the local time zone (PR_FALSE) or GMT (PR_TRUE).
+ * The correct value for this argument depends on what standard specified
+ * the time string which you are parsing.
+ */
+
+NSPR_API(PRStatus) PR_ParseTimeString (
+        const char *string,
+        PRBool default_to_gmt,
+        PRTime *result);
+
+/*
+ * FIXME: should we also have a formatting function, such as asctime, ctime,
+ * and strftime in standard C library?  But this would involve
+ * internationalization issues.  Might want to provide a US English version.
+ */
+
+/**********************************************************************/
+/*********************** OLD COMPATIBILITYFUNCTIONS *******************/
+/**********************************************************************/
+#ifndef NO_NSPR_10_SUPPORT
+
+/* Format a time value into a buffer. Same semantics as strftime() */
+NSPR_API(PRUint32) PR_FormatTime(char *buf, int buflen, const char *fmt, 
+                                           const PRExplodedTime *tm);
+
+/* Format a time value into a buffer. Time is always in US English format, regardless
+ * of locale setting.
+ */
+NSPR_API(PRUint32)
+PR_FormatTimeUSEnglish( char* buf, PRUint32 bufSize,
+                        const char* format, const PRExplodedTime* tm );
+
+#endif /* NO_NSPR_10_SUPPORT */
+
+PR_END_EXTERN_C
+
+#endif /* prtime_h___ */