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 /* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 2 -*- */

 /* This Source Code Form is subject to the terms of the Mozilla Public

  * License, v. 2.0. If a copy of the MPL was not distributed with this

  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

 /*

  *----------------------------------------------------------------------

  *

  * 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		1000L

 #define PR_USEC_PER_SEC		1000000L

 #define PR_NSEC_PER_SEC		1000000000L

 #define PR_USEC_PER_MSEC	1000L

 #define PR_NSEC_PER_MSEC	1000000L

 /*

  * 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.

  */

 NSPR_API(PRTime)

 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 */

 NSPR_API(PRTime)

 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 PRExplodedTime

  * struct. It populates all fields but it can't split

  * the offset from UTC into tp_gmt_offset and tp_dst_offset in

  * most cases (exceptions: PST/PDT, MST/MDT, CST/CDT, EST/EDT, GMT/BST).

  * In those cases tp_gmt_offset will be the sum of these two and

  * tp_dst_offset will be 0.

  * 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_ParseTimeStringToExplodedTime (

         const char *string,

         PRBool default_to_gmt,

         PRExplodedTime *result);

 /*

  * This uses PR_ParseTimeStringToExplodedTime to parse

  * a time/date string and PR_ImplodeTime to transform it 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.

  */

 NSPR_API(PRStatus) PR_ParseTimeString (

 	const char *string,

 	PRBool default_to_gmt,

 	PRTime *result);

 /* 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 );

 PR_END_EXTERN_C

 #endif /* prtime_h___ */