1.1 --- /dev/null Thu Jan 01 00:00:00 1970 +0000
1.2 +++ b/intl/icu/source/i18n/unicode/utmscale.h Wed Dec 31 06:09:35 2014 +0100
1.3 @@ -0,0 +1,481 @@
1.4 +/*
1.5 +*******************************************************************************
1.6 +* Copyright (C) 2004 - 2008, International Business Machines Corporation and
1.7 +* others. All Rights Reserved.
1.8 +*******************************************************************************
1.9 +*/
1.10 +
1.11 +#ifndef UTMSCALE_H
1.12 +#define UTMSCALE_H
1.13 +
1.14 +#include "unicode/utypes.h"
1.15 +
1.16 +#if !UCONFIG_NO_FORMATTING
1.17 +
1.18 +/**
1.19 + * \file
1.20 + * \brief C API: Universal Time Scale
1.21 + *
1.22 + * There are quite a few different conventions for binary datetime, depending on different
1.23 + * platforms and protocols. Some of these have severe drawbacks. For example, people using
1.24 + * Unix time (seconds since Jan 1, 1970) think that they are safe until near the year 2038.
1.25 + * But cases can and do arise where arithmetic manipulations causes serious problems. Consider
1.26 + * the computation of the average of two datetimes, for example: if one calculates them with
1.27 + * <code>averageTime = (time1 + time2)/2</code>, there will be overflow even with dates
1.28 + * around the present. Moreover, even if these problems don't occur, there is the issue of
1.29 + * conversion back and forth between different systems.
1.30 + *
1.31 + * <p>
1.32 + * Binary datetimes differ in a number of ways: the datatype, the unit,
1.33 + * and the epoch (origin). We'll refer to these as time scales. For example:
1.34 + *
1.35 + * <table border="1" cellspacing="0" cellpadding="4">
1.36 + * <caption>Table 1: Binary Time Scales</caption>
1.37 + * <tr>
1.38 + * <th align="left">Source</th>
1.39 + * <th align="left">Datatype</th>
1.40 + * <th align="left">Unit</th>
1.41 + * <th align="left">Epoch</th>
1.42 + * </tr>
1.43 + *
1.44 + * <tr>
1.45 + * <td>UDTS_JAVA_TIME</td>
1.46 + * <td>int64_t</td>
1.47 + * <td>milliseconds</td>
1.48 + * <td>Jan 1, 1970</td>
1.49 + * </tr>
1.50 + * <tr>
1.51 + *
1.52 + * <td>UDTS_UNIX_TIME</td>
1.53 + * <td>int32_t or int64_t</td>
1.54 + * <td>seconds</td>
1.55 + * <td>Jan 1, 1970</td>
1.56 + * </tr>
1.57 + * <tr>
1.58 + * <td>UDTS_ICU4C_TIME</td>
1.59 + *
1.60 + * <td>double</td>
1.61 + * <td>milliseconds</td>
1.62 + * <td>Jan 1, 1970</td>
1.63 + * </tr>
1.64 + * <tr>
1.65 + * <td>UDTS_WINDOWS_FILE_TIME</td>
1.66 + * <td>int64_t</td>
1.67 + *
1.68 + * <td>ticks (100 nanoseconds)</td>
1.69 + * <td>Jan 1, 1601</td>
1.70 + * </tr>
1.71 + * <tr>
1.72 + * <td>UDTS_DOTNET_DATE_TIME</td>
1.73 + * <td>int64_t</td>
1.74 + * <td>ticks (100 nanoseconds)</td>
1.75 + *
1.76 + * <td>Jan 1, 0001</td>
1.77 + * </tr>
1.78 + * <tr>
1.79 + * <td>UDTS_MAC_OLD_TIME</td>
1.80 + * <td>int32_t or int64_t</td>
1.81 + * <td>seconds</td>
1.82 + * <td>Jan 1, 1904</td>
1.83 + *
1.84 + * </tr>
1.85 + * <tr>
1.86 + * <td>UDTS_MAC_TIME</td>
1.87 + * <td>double</td>
1.88 + * <td>seconds</td>
1.89 + * <td>Jan 1, 2001</td>
1.90 + * </tr>
1.91 + *
1.92 + * <tr>
1.93 + * <td>UDTS_EXCEL_TIME</td>
1.94 + * <td>?</td>
1.95 + * <td>days</td>
1.96 + * <td>Dec 31, 1899</td>
1.97 + * </tr>
1.98 + * <tr>
1.99 + *
1.100 + * <td>UDTS_DB2_TIME</td>
1.101 + * <td>?</td>
1.102 + * <td>days</td>
1.103 + * <td>Dec 31, 1899</td>
1.104 + * </tr>
1.105 + *
1.106 + * <tr>
1.107 + * <td>UDTS_UNIX_MICROSECONDS_TIME</td>
1.108 + * <td>int64_t</td>
1.109 + * <td>microseconds</td>
1.110 + * <td>Jan 1, 1970</td>
1.111 + * </tr>
1.112 + * </table>
1.113 + *
1.114 + * <p>
1.115 + * All of the epochs start at 00:00 am (the earliest possible time on the day in question),
1.116 + * and are assumed to be UTC.
1.117 + *
1.118 + * <p>
1.119 + * The ranges for different datatypes are given in the following table (all values in years).
1.120 + * The range of years includes the entire range expressible with positive and negative
1.121 + * values of the datatype. The range of years for double is the range that would be allowed
1.122 + * without losing precision to the corresponding unit.
1.123 + *
1.124 + * <table border="1" cellspacing="0" cellpadding="4">
1.125 + * <tr>
1.126 + * <th align="left">Units</th>
1.127 + * <th align="left">int64_t</th>
1.128 + * <th align="left">double</th>
1.129 + * <th align="left">int32_t</th>
1.130 + * </tr>
1.131 + *
1.132 + * <tr>
1.133 + * <td>1 sec</td>
1.134 + * <td align="right">5.84542x10<sup>11</sup></td>
1.135 + * <td align="right">285,420,920.94</td>
1.136 + * <td align="right">136.10</td>
1.137 + * </tr>
1.138 + * <tr>
1.139 + *
1.140 + * <td>1 millisecond</td>
1.141 + * <td align="right">584,542,046.09</td>
1.142 + * <td align="right">285,420.92</td>
1.143 + * <td align="right">0.14</td>
1.144 + * </tr>
1.145 + * <tr>
1.146 + * <td>1 microsecond</td>
1.147 + *
1.148 + * <td align="right">584,542.05</td>
1.149 + * <td align="right">285.42</td>
1.150 + * <td align="right">0.00</td>
1.151 + * </tr>
1.152 + * <tr>
1.153 + * <td>100 nanoseconds (tick)</td>
1.154 + * <td align="right">58,454.20</td>
1.155 + * <td align="right">28.54</td>
1.156 + * <td align="right">0.00</td>
1.157 + * </tr>
1.158 + * <tr>
1.159 + * <td>1 nanosecond</td>
1.160 + * <td align="right">584.5420461</td>
1.161 + * <td align="right">0.2854</td>
1.162 + * <td align="right">0.00</td>
1.163 + * </tr>
1.164 + * </table>
1.165 + *
1.166 + * <p>
1.167 + * These functions implement a universal time scale which can be used as a 'pivot',
1.168 + * and provide conversion functions to and from all other major time scales.
1.169 + * This datetimes to be converted to the pivot time, safely manipulated,
1.170 + * and converted back to any other datetime time scale.
1.171 + *
1.172 + *<p>
1.173 + * So what to use for this pivot? Java time has plenty of range, but cannot represent
1.174 + * .NET <code>System.DateTime</code> values without severe loss of precision. ICU4C time addresses this by using a
1.175 + * <code>double</code> that is otherwise equivalent to the Java time. However, there are disadvantages
1.176 + * with <code>doubles</code>. They provide for much more graceful degradation in arithmetic operations.
1.177 + * But they only have 53 bits of accuracy, which means that they will lose precision when
1.178 + * converting back and forth to ticks. What would really be nice would be a
1.179 + * <code>long double</code> (80 bits -- 64 bit mantissa), but that is not supported on most systems.
1.180 + *
1.181 + *<p>
1.182 + * The Unix extended time uses a structure with two components: time in seconds and a
1.183 + * fractional field (microseconds). However, this is clumsy, slow, and
1.184 + * prone to error (you always have to keep track of overflow and underflow in the
1.185 + * fractional field). <code>BigDecimal</code> would allow for arbitrary precision and arbitrary range,
1.186 + * but we do not want to use this as the normal type, because it is slow and does not
1.187 + * have a fixed size.
1.188 + *
1.189 + *<p>
1.190 + * Because of these issues, we ended up concluding that the .NET framework's
1.191 + * <code>System.DateTime</code> would be the best pivot. However, we use the full range
1.192 + * allowed by the datatype, allowing for datetimes back to 29,000 BC and up to 29,000 AD.
1.193 + * This time scale is very fine grained, does not lose precision, and covers a range that
1.194 + * will meet almost all requirements. It will not handle the range that Java times do,
1.195 + * but frankly, being able to handle dates before 29,000 BC or after 29,000 AD is of very limited interest.
1.196 + *
1.197 + */
1.198 +
1.199 +/**
1.200 + * <code>UDateTimeScale</code> values are used to specify the time scale used for
1.201 + * conversion into or out if the universal time scale.
1.202 + *
1.203 + * @stable ICU 3.2
1.204 + */
1.205 +typedef enum UDateTimeScale {
1.206 + /**
1.207 + * Used in the JDK. Data is a Java <code>long</code> (<code>int64_t</code>). Value
1.208 + * is milliseconds since January 1, 1970.
1.209 + *
1.210 + * @stable ICU 3.2
1.211 + */
1.212 + UDTS_JAVA_TIME = 0,
1.213 +
1.214 + /**
1.215 + * Used on Unix systems. Data is <code>int32_t</code> or <code>int64_t</code>. Value
1.216 + * is seconds since January 1, 1970.
1.217 + *
1.218 + * @stable ICU 3.2
1.219 + */
1.220 + UDTS_UNIX_TIME,
1.221 +
1.222 + /**
1.223 + * Used in IUC4C. Data is a <code>double</code>. Value
1.224 + * is milliseconds since January 1, 1970.
1.225 + *
1.226 + * @stable ICU 3.2
1.227 + */
1.228 + UDTS_ICU4C_TIME,
1.229 +
1.230 + /**
1.231 + * Used in Windows for file times. Data is an <code>int64_t</code>. Value
1.232 + * is ticks (1 tick == 100 nanoseconds) since January 1, 1601.
1.233 + *
1.234 + * @stable ICU 3.2
1.235 + */
1.236 + UDTS_WINDOWS_FILE_TIME,
1.237 +
1.238 + /**
1.239 + * Used in the .NET framework's <code>System.DateTime</code> structure. Data is an <code>int64_t</code>. Value
1.240 + * is ticks (1 tick == 100 nanoseconds) since January 1, 0001.
1.241 + *
1.242 + * @stable ICU 3.2
1.243 + */
1.244 + UDTS_DOTNET_DATE_TIME,
1.245 +
1.246 + /**
1.247 + * Used in older Macintosh systems. Data is <code>int32_t</code> or <code>int64_t</code>. Value
1.248 + * is seconds since January 1, 1904.
1.249 + *
1.250 + * @stable ICU 3.2
1.251 + */
1.252 + UDTS_MAC_OLD_TIME,
1.253 +
1.254 + /**
1.255 + * Used in newer Macintosh systems. Data is a <code>double</code>. Value
1.256 + * is seconds since January 1, 2001.
1.257 + *
1.258 + * @stable ICU 3.2
1.259 + */
1.260 + UDTS_MAC_TIME,
1.261 +
1.262 + /**
1.263 + * Used in Excel. Data is an <code>?unknown?</code>. Value
1.264 + * is days since December 31, 1899.
1.265 + *
1.266 + * @stable ICU 3.2
1.267 + */
1.268 + UDTS_EXCEL_TIME,
1.269 +
1.270 + /**
1.271 + * Used in DB2. Data is an <code>?unknown?</code>. Value
1.272 + * is days since December 31, 1899.
1.273 + *
1.274 + * @stable ICU 3.2
1.275 + */
1.276 + UDTS_DB2_TIME,
1.277 +
1.278 + /**
1.279 + * Data is a <code>long</code>. Value is microseconds since January 1, 1970.
1.280 + * Similar to Unix time (linear value from 1970) and struct timeval
1.281 + * (microseconds resolution).
1.282 + *
1.283 + * @stable ICU 3.8
1.284 + */
1.285 + UDTS_UNIX_MICROSECONDS_TIME,
1.286 +
1.287 + /**
1.288 + * The first unused time scale value. The limit of this enum
1.289 + */
1.290 + UDTS_MAX_SCALE
1.291 +} UDateTimeScale;
1.292 +
1.293 +/**
1.294 + * <code>UTimeScaleValue</code> values are used to specify the time scale values
1.295 + * to <code>utmscale_getTimeScaleValue</code>.
1.296 + *
1.297 + * @see utmscale_getTimeScaleValue
1.298 + *
1.299 + * @stable ICU 3.2
1.300 + */
1.301 +typedef enum UTimeScaleValue {
1.302 + /**
1.303 + * The constant used to select the units vale
1.304 + * for a time scale.
1.305 + *
1.306 + * @see utmscale_getTimeScaleValue
1.307 + *
1.308 + * @stable ICU 3.2
1.309 + */
1.310 + UTSV_UNITS_VALUE = 0,
1.311 +
1.312 + /**
1.313 + * The constant used to select the epoch offset value
1.314 + * for a time scale.
1.315 + *
1.316 + * @see utmscale_getTimeScaleValue
1.317 + *
1.318 + * @stable ICU 3.2
1.319 + */
1.320 + UTSV_EPOCH_OFFSET_VALUE=1,
1.321 +
1.322 + /**
1.323 + * The constant used to select the minimum from value
1.324 + * for a time scale.
1.325 + *
1.326 + * @see utmscale_getTimeScaleValue
1.327 + *
1.328 + * @stable ICU 3.2
1.329 + */
1.330 + UTSV_FROM_MIN_VALUE=2,
1.331 +
1.332 + /**
1.333 + * The constant used to select the maximum from value
1.334 + * for a time scale.
1.335 + *
1.336 + * @see utmscale_getTimeScaleValue
1.337 + *
1.338 + * @stable ICU 3.2
1.339 + */
1.340 + UTSV_FROM_MAX_VALUE=3,
1.341 +
1.342 + /**
1.343 + * The constant used to select the minimum to value
1.344 + * for a time scale.
1.345 + *
1.346 + * @see utmscale_getTimeScaleValue
1.347 + *
1.348 + * @stable ICU 3.2
1.349 + */
1.350 + UTSV_TO_MIN_VALUE=4,
1.351 +
1.352 + /**
1.353 + * The constant used to select the maximum to value
1.354 + * for a time scale.
1.355 + *
1.356 + * @see utmscale_getTimeScaleValue
1.357 + *
1.358 + * @stable ICU 3.2
1.359 + */
1.360 + UTSV_TO_MAX_VALUE=5,
1.361 +
1.362 +#ifndef U_HIDE_INTERNAL_API
1.363 + /**
1.364 + * The constant used to select the epoch plus one value
1.365 + * for a time scale.
1.366 + *
1.367 + * NOTE: This is an internal value. DO NOT USE IT. May not
1.368 + * actually be equal to the epoch offset value plus one.
1.369 + *
1.370 + * @see utmscale_getTimeScaleValue
1.371 + *
1.372 + * @internal ICU 3.2
1.373 + */
1.374 + UTSV_EPOCH_OFFSET_PLUS_1_VALUE=6,
1.375 +
1.376 + /**
1.377 + * The constant used to select the epoch plus one value
1.378 + * for a time scale.
1.379 + *
1.380 + * NOTE: This is an internal value. DO NOT USE IT. May not
1.381 + * actually be equal to the epoch offset value plus one.
1.382 + *
1.383 + * @see utmscale_getTimeScaleValue
1.384 + *
1.385 + * @internal ICU 3.2
1.386 + */
1.387 + UTSV_EPOCH_OFFSET_MINUS_1_VALUE=7,
1.388 +
1.389 + /**
1.390 + * The constant used to select the units round value
1.391 + * for a time scale.
1.392 + *
1.393 + * NOTE: This is an internal value. DO NOT USE IT.
1.394 + *
1.395 + * @see utmscale_getTimeScaleValue
1.396 + *
1.397 + * @internal ICU 3.2
1.398 + */
1.399 + UTSV_UNITS_ROUND_VALUE=8,
1.400 +
1.401 + /**
1.402 + * The constant used to select the minimum safe rounding value
1.403 + * for a time scale.
1.404 + *
1.405 + * NOTE: This is an internal value. DO NOT USE IT.
1.406 + *
1.407 + * @see utmscale_getTimeScaleValue
1.408 + *
1.409 + * @internal ICU 3.2
1.410 + */
1.411 + UTSV_MIN_ROUND_VALUE=9,
1.412 +
1.413 + /**
1.414 + * The constant used to select the maximum safe rounding value
1.415 + * for a time scale.
1.416 + *
1.417 + * NOTE: This is an internal value. DO NOT USE IT.
1.418 + *
1.419 + * @see utmscale_getTimeScaleValue
1.420 + *
1.421 + * @internal ICU 3.2
1.422 + */
1.423 + UTSV_MAX_ROUND_VALUE=10,
1.424 +
1.425 +#endif /* U_HIDE_INTERNAL_API */
1.426 +
1.427 + /**
1.428 + * The number of time scale values, in other words limit of this enum.
1.429 + *
1.430 + * @see utmscale_getTimeScaleValue
1.431 + */
1.432 + UTSV_MAX_SCALE_VALUE=11
1.433 +
1.434 +} UTimeScaleValue;
1.435 +
1.436 +/**
1.437 + * Get a value associated with a particular time scale.
1.438 + *
1.439 + * @param timeScale The time scale
1.440 + * @param value A constant representing the value to get
1.441 + * @param status The status code. Set to <code>U_ILLEGAL_ARGUMENT_ERROR</code> if arguments are invalid.
1.442 + * @return - the value.
1.443 + *
1.444 + * @stable ICU 3.2
1.445 + */
1.446 +U_STABLE int64_t U_EXPORT2
1.447 + utmscale_getTimeScaleValue(UDateTimeScale timeScale, UTimeScaleValue value, UErrorCode *status);
1.448 +
1.449 +/* Conversion to 'universal time scale' */
1.450 +
1.451 +/**
1.452 + * Convert a <code>int64_t</code> datetime from the given time scale to the universal time scale.
1.453 + *
1.454 + * @param otherTime The <code>int64_t</code> datetime
1.455 + * @param timeScale The time scale to convert from
1.456 + * @param status The status code. Set to <code>U_ILLEGAL_ARGUMENT_ERROR</code> if the conversion is out of range.
1.457 + *
1.458 + * @return The datetime converted to the universal time scale
1.459 + *
1.460 + * @stable ICU 3.2
1.461 + */
1.462 +U_STABLE int64_t U_EXPORT2
1.463 + utmscale_fromInt64(int64_t otherTime, UDateTimeScale timeScale, UErrorCode *status);
1.464 +
1.465 +/* Conversion from 'universal time scale' */
1.466 +
1.467 +/**
1.468 + * Convert a datetime from the universal time scale to a <code>int64_t</code> in the given time scale.
1.469 + *
1.470 + * @param universalTime The datetime in the universal time scale
1.471 + * @param timeScale The time scale to convert to
1.472 + * @param status The status code. Set to <code>U_ILLEGAL_ARGUMENT_ERROR</code> if the conversion is out of range.
1.473 + *
1.474 + * @return The datetime converted to the given time scale
1.475 + *
1.476 + * @stable ICU 3.2
1.477 + */
1.478 +U_STABLE int64_t U_EXPORT2
1.479 + utmscale_toInt64(int64_t universalTime, UDateTimeScale timeScale, UErrorCode *status);
1.480 +
1.481 +#endif /* #if !UCONFIG_NO_FORMATTING */
1.482 +
1.483 +#endif
1.484 +
