prtime.h (10235B)
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 21 PR_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 48 typedef 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 55 typedef 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 83 typedef 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 */ 125 126 typedef 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 */ 145 NSPR_API(PRTime) 146 PR_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 */ 157 158 NSPR_API(void) PR_ExplodeTime( 159 PRTime usecs, PRTimeParamFn params, PRExplodedTime *exploded); 160 161 /* Reverse operation of PR_ExplodeTime */ 162 NSPR_API(PRTime) 163 PR_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 */ 176 177 NSPR_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 */ 185 NSPR_API(PRTimeParameters) PR_LocalTimeParameters(const PRExplodedTime *gmt); 186 187 /* Time parameters that represent Greenwich Mean Time */ 188 NSPR_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 */ 194 NSPR_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 */ 230 231 NSPR_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 */ 243 244 NSPR_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() */ 250 NSPR_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 */ 256 NSPR_API(PRUint32) 257 PR_FormatTimeUSEnglish(char *buf, PRUint32 bufSize, 258 const char *format, const PRExplodedTime *time); 259 260 PR_END_EXTERN_C 261 262 #endif /* prtime_h___ */