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diff --git a/intl/icu/source/i18n/unicode/utmscale.h b/intl/icu/source/i18n/unicode/utmscale.h new file mode 100644 index 000000000..8f3c42a9e --- /dev/null +++ b/intl/icu/source/i18n/unicode/utmscale.h @@ -0,0 +1,483 @@ +// Copyright (C) 2016 and later: Unicode, Inc. and others. +// License & terms of use: http://www.unicode.org/copyright.html +/* +******************************************************************************* +* Copyright (C) 2004 - 2008, International Business Machines Corporation and +* others. All Rights Reserved. +******************************************************************************* +*/ + +#ifndef UTMSCALE_H +#define UTMSCALE_H + +#include "unicode/utypes.h" + +#if !UCONFIG_NO_FORMATTING + +/** + * \file + * \brief C API: Universal Time Scale + * + * There are quite a few different conventions for binary datetime, depending on different + * platforms and protocols. Some of these have severe drawbacks. For example, people using + * Unix time (seconds since Jan 1, 1970) think that they are safe until near the year 2038. + * But cases can and do arise where arithmetic manipulations causes serious problems. Consider + * the computation of the average of two datetimes, for example: if one calculates them with + * <code>averageTime = (time1 + time2)/2</code>, there will be overflow even with dates + * around the present. Moreover, even if these problems don't occur, there is the issue of + * conversion back and forth between different systems. + * + * <p> + * Binary datetimes differ in a number of ways: the datatype, the unit, + * and the epoch (origin). We'll refer to these as time scales. For example: + * + * <table border="1" cellspacing="0" cellpadding="4"> + * <caption>Table 1: Binary Time Scales</caption> + * <tr> + * <th align="left">Source</th> + * <th align="left">Datatype</th> + * <th align="left">Unit</th> + * <th align="left">Epoch</th> + * </tr> + * + * <tr> + * <td>UDTS_JAVA_TIME</td> + * <td>int64_t</td> + * <td>milliseconds</td> + * <td>Jan 1, 1970</td> + * </tr> + * <tr> + * + * <td>UDTS_UNIX_TIME</td> + * <td>int32_t or int64_t</td> + * <td>seconds</td> + * <td>Jan 1, 1970</td> + * </tr> + * <tr> + * <td>UDTS_ICU4C_TIME</td> + * + * <td>double</td> + * <td>milliseconds</td> + * <td>Jan 1, 1970</td> + * </tr> + * <tr> + * <td>UDTS_WINDOWS_FILE_TIME</td> + * <td>int64_t</td> + * + * <td>ticks (100 nanoseconds)</td> + * <td>Jan 1, 1601</td> + * </tr> + * <tr> + * <td>UDTS_DOTNET_DATE_TIME</td> + * <td>int64_t</td> + * <td>ticks (100 nanoseconds)</td> + * + * <td>Jan 1, 0001</td> + * </tr> + * <tr> + * <td>UDTS_MAC_OLD_TIME</td> + * <td>int32_t or int64_t</td> + * <td>seconds</td> + * <td>Jan 1, 1904</td> + * + * </tr> + * <tr> + * <td>UDTS_MAC_TIME</td> + * <td>double</td> + * <td>seconds</td> + * <td>Jan 1, 2001</td> + * </tr> + * + * <tr> + * <td>UDTS_EXCEL_TIME</td> + * <td>?</td> + * <td>days</td> + * <td>Dec 31, 1899</td> + * </tr> + * <tr> + * + * <td>UDTS_DB2_TIME</td> + * <td>?</td> + * <td>days</td> + * <td>Dec 31, 1899</td> + * </tr> + * + * <tr> + * <td>UDTS_UNIX_MICROSECONDS_TIME</td> + * <td>int64_t</td> + * <td>microseconds</td> + * <td>Jan 1, 1970</td> + * </tr> + * </table> + * + * <p> + * All of the epochs start at 00:00 am (the earliest possible time on the day in question), + * and are assumed to be UTC. + * + * <p> + * The ranges for different datatypes are given in the following table (all values in years). + * The range of years includes the entire range expressible with positive and negative + * values of the datatype. The range of years for double is the range that would be allowed + * without losing precision to the corresponding unit. + * + * <table border="1" cellspacing="0" cellpadding="4"> + * <tr> + * <th align="left">Units</th> + * <th align="left">int64_t</th> + * <th align="left">double</th> + * <th align="left">int32_t</th> + * </tr> + * + * <tr> + * <td>1 sec</td> + * <td align="right">5.84542x10<sup>11</sup></td> + * <td align="right">285,420,920.94</td> + * <td align="right">136.10</td> + * </tr> + * <tr> + * + * <td>1 millisecond</td> + * <td align="right">584,542,046.09</td> + * <td align="right">285,420.92</td> + * <td align="right">0.14</td> + * </tr> + * <tr> + * <td>1 microsecond</td> + * + * <td align="right">584,542.05</td> + * <td align="right">285.42</td> + * <td align="right">0.00</td> + * </tr> + * <tr> + * <td>100 nanoseconds (tick)</td> + * <td align="right">58,454.20</td> + * <td align="right">28.54</td> + * <td align="right">0.00</td> + * </tr> + * <tr> + * <td>1 nanosecond</td> + * <td align="right">584.5420461</td> + * <td align="right">0.2854</td> + * <td align="right">0.00</td> + * </tr> + * </table> + * + * <p> + * These functions implement a universal time scale which can be used as a 'pivot', + * and provide conversion functions to and from all other major time scales. + * This datetimes to be converted to the pivot time, safely manipulated, + * and converted back to any other datetime time scale. + * + *<p> + * So what to use for this pivot? Java time has plenty of range, but cannot represent + * .NET <code>System.DateTime</code> values without severe loss of precision. ICU4C time addresses this by using a + * <code>double</code> that is otherwise equivalent to the Java time. However, there are disadvantages + * with <code>doubles</code>. They provide for much more graceful degradation in arithmetic operations. + * But they only have 53 bits of accuracy, which means that they will lose precision when + * converting back and forth to ticks. What would really be nice would be a + * <code>long double</code> (80 bits -- 64 bit mantissa), but that is not supported on most systems. + * + *<p> + * The Unix extended time uses a structure with two components: time in seconds and a + * fractional field (microseconds). However, this is clumsy, slow, and + * prone to error (you always have to keep track of overflow and underflow in the + * fractional field). <code>BigDecimal</code> would allow for arbitrary precision and arbitrary range, + * but we do not want to use this as the normal type, because it is slow and does not + * have a fixed size. + * + *<p> + * Because of these issues, we ended up concluding that the .NET framework's + * <code>System.DateTime</code> would be the best pivot. However, we use the full range + * allowed by the datatype, allowing for datetimes back to 29,000 BC and up to 29,000 AD. + * This time scale is very fine grained, does not lose precision, and covers a range that + * will meet almost all requirements. It will not handle the range that Java times do, + * but frankly, being able to handle dates before 29,000 BC or after 29,000 AD is of very limited interest. + * + */ + +/** + * <code>UDateTimeScale</code> values are used to specify the time scale used for + * conversion into or out if the universal time scale. + * + * @stable ICU 3.2 + */ +typedef enum UDateTimeScale { + /** + * Used in the JDK. Data is a Java <code>long</code> (<code>int64_t</code>). Value + * is milliseconds since January 1, 1970. + * + * @stable ICU 3.2 + */ + UDTS_JAVA_TIME = 0, + + /** + * Used on Unix systems. Data is <code>int32_t</code> or <code>int64_t</code>. Value + * is seconds since January 1, 1970. + * + * @stable ICU 3.2 + */ + UDTS_UNIX_TIME, + + /** + * Used in IUC4C. Data is a <code>double</code>. Value + * is milliseconds since January 1, 1970. + * + * @stable ICU 3.2 + */ + UDTS_ICU4C_TIME, + + /** + * Used in Windows for file times. Data is an <code>int64_t</code>. Value + * is ticks (1 tick == 100 nanoseconds) since January 1, 1601. + * + * @stable ICU 3.2 + */ + UDTS_WINDOWS_FILE_TIME, + + /** + * Used in the .NET framework's <code>System.DateTime</code> structure. Data is an <code>int64_t</code>. Value + * is ticks (1 tick == 100 nanoseconds) since January 1, 0001. + * + * @stable ICU 3.2 + */ + UDTS_DOTNET_DATE_TIME, + + /** + * Used in older Macintosh systems. Data is <code>int32_t</code> or <code>int64_t</code>. Value + * is seconds since January 1, 1904. + * + * @stable ICU 3.2 + */ + UDTS_MAC_OLD_TIME, + + /** + * Used in newer Macintosh systems. Data is a <code>double</code>. Value + * is seconds since January 1, 2001. + * + * @stable ICU 3.2 + */ + UDTS_MAC_TIME, + + /** + * Used in Excel. Data is an <code>?unknown?</code>. Value + * is days since December 31, 1899. + * + * @stable ICU 3.2 + */ + UDTS_EXCEL_TIME, + + /** + * Used in DB2. Data is an <code>?unknown?</code>. Value + * is days since December 31, 1899. + * + * @stable ICU 3.2 + */ + UDTS_DB2_TIME, + + /** + * Data is a <code>long</code>. Value is microseconds since January 1, 1970. + * Similar to Unix time (linear value from 1970) and struct timeval + * (microseconds resolution). + * + * @stable ICU 3.8 + */ + UDTS_UNIX_MICROSECONDS_TIME, + + /** + * The first unused time scale value. The limit of this enum + */ + UDTS_MAX_SCALE +} UDateTimeScale; + +/** + * <code>UTimeScaleValue</code> values are used to specify the time scale values + * to <code>utmscale_getTimeScaleValue</code>. + * + * @see utmscale_getTimeScaleValue + * + * @stable ICU 3.2 + */ +typedef enum UTimeScaleValue { + /** + * The constant used to select the units vale + * for a time scale. + * + * @see utmscale_getTimeScaleValue + * + * @stable ICU 3.2 + */ + UTSV_UNITS_VALUE = 0, + + /** + * The constant used to select the epoch offset value + * for a time scale. + * + * @see utmscale_getTimeScaleValue + * + * @stable ICU 3.2 + */ + UTSV_EPOCH_OFFSET_VALUE=1, + + /** + * The constant used to select the minimum from value + * for a time scale. + * + * @see utmscale_getTimeScaleValue + * + * @stable ICU 3.2 + */ + UTSV_FROM_MIN_VALUE=2, + + /** + * The constant used to select the maximum from value + * for a time scale. + * + * @see utmscale_getTimeScaleValue + * + * @stable ICU 3.2 + */ + UTSV_FROM_MAX_VALUE=3, + + /** + * The constant used to select the minimum to value + * for a time scale. + * + * @see utmscale_getTimeScaleValue + * + * @stable ICU 3.2 + */ + UTSV_TO_MIN_VALUE=4, + + /** + * The constant used to select the maximum to value + * for a time scale. + * + * @see utmscale_getTimeScaleValue + * + * @stable ICU 3.2 + */ + UTSV_TO_MAX_VALUE=5, + +#ifndef U_HIDE_INTERNAL_API + /** + * The constant used to select the epoch plus one value + * for a time scale. + * + * NOTE: This is an internal value. DO NOT USE IT. May not + * actually be equal to the epoch offset value plus one. + * + * @see utmscale_getTimeScaleValue + * + * @internal ICU 3.2 + */ + UTSV_EPOCH_OFFSET_PLUS_1_VALUE=6, + + /** + * The constant used to select the epoch plus one value + * for a time scale. + * + * NOTE: This is an internal value. DO NOT USE IT. May not + * actually be equal to the epoch offset value plus one. + * + * @see utmscale_getTimeScaleValue + * + * @internal ICU 3.2 + */ + UTSV_EPOCH_OFFSET_MINUS_1_VALUE=7, + + /** + * The constant used to select the units round value + * for a time scale. + * + * NOTE: This is an internal value. DO NOT USE IT. + * + * @see utmscale_getTimeScaleValue + * + * @internal ICU 3.2 + */ + UTSV_UNITS_ROUND_VALUE=8, + + /** + * The constant used to select the minimum safe rounding value + * for a time scale. + * + * NOTE: This is an internal value. DO NOT USE IT. + * + * @see utmscale_getTimeScaleValue + * + * @internal ICU 3.2 + */ + UTSV_MIN_ROUND_VALUE=9, + + /** + * The constant used to select the maximum safe rounding value + * for a time scale. + * + * NOTE: This is an internal value. DO NOT USE IT. + * + * @see utmscale_getTimeScaleValue + * + * @internal ICU 3.2 + */ + UTSV_MAX_ROUND_VALUE=10, + +#endif /* U_HIDE_INTERNAL_API */ + + /** + * The number of time scale values, in other words limit of this enum. + * + * @see utmscale_getTimeScaleValue + */ + UTSV_MAX_SCALE_VALUE=11 + +} UTimeScaleValue; + +/** + * Get a value associated with a particular time scale. + * + * @param timeScale The time scale + * @param value A constant representing the value to get + * @param status The status code. Set to <code>U_ILLEGAL_ARGUMENT_ERROR</code> if arguments are invalid. + * @return - the value. + * + * @stable ICU 3.2 + */ +U_STABLE int64_t U_EXPORT2 + utmscale_getTimeScaleValue(UDateTimeScale timeScale, UTimeScaleValue value, UErrorCode *status); + +/* Conversion to 'universal time scale' */ + +/** + * Convert a <code>int64_t</code> datetime from the given time scale to the universal time scale. + * + * @param otherTime The <code>int64_t</code> datetime + * @param timeScale The time scale to convert from + * @param status The status code. Set to <code>U_ILLEGAL_ARGUMENT_ERROR</code> if the conversion is out of range. + * + * @return The datetime converted to the universal time scale + * + * @stable ICU 3.2 + */ +U_STABLE int64_t U_EXPORT2 + utmscale_fromInt64(int64_t otherTime, UDateTimeScale timeScale, UErrorCode *status); + +/* Conversion from 'universal time scale' */ + +/** + * Convert a datetime from the universal time scale to a <code>int64_t</code> in the given time scale. + * + * @param universalTime The datetime in the universal time scale + * @param timeScale The time scale to convert to + * @param status The status code. Set to <code>U_ILLEGAL_ARGUMENT_ERROR</code> if the conversion is out of range. + * + * @return The datetime converted to the given time scale + * + * @stable ICU 3.2 + */ +U_STABLE int64_t U_EXPORT2 + utmscale_toInt64(int64_t universalTime, UDateTimeScale timeScale, UErrorCode *status); + +#endif /* #if !UCONFIG_NO_FORMATTING */ + +#endif + |