jpayne@69: // © 2016 and later: Unicode, Inc. and others. jpayne@69: // License & terms of use: http://www.unicode.org/copyright.html jpayne@69: /* jpayne@69: ******************************************************************************* jpayne@69: * Copyright (C) 2004 - 2008, International Business Machines Corporation and jpayne@69: * others. All Rights Reserved. jpayne@69: ******************************************************************************* jpayne@69: */ jpayne@69: jpayne@69: #ifndef UTMSCALE_H jpayne@69: #define UTMSCALE_H jpayne@69: jpayne@69: #include "unicode/utypes.h" jpayne@69: jpayne@69: #if !UCONFIG_NO_FORMATTING jpayne@69: jpayne@69: /** jpayne@69: * \file jpayne@69: * \brief C API: Universal Time Scale jpayne@69: * jpayne@69: * There are quite a few different conventions for binary datetime, depending on different jpayne@69: * platforms and protocols. Some of these have severe drawbacks. For example, people using jpayne@69: * Unix time (seconds since Jan 1, 1970) think that they are safe until near the year 2038. jpayne@69: * But cases can and do arise where arithmetic manipulations causes serious problems. Consider jpayne@69: * the computation of the average of two datetimes, for example: if one calculates them with jpayne@69: * averageTime = (time1 + time2)/2, there will be overflow even with dates jpayne@69: * around the present. Moreover, even if these problems don't occur, there is the issue of jpayne@69: * conversion back and forth between different systems. jpayne@69: * jpayne@69: *

jpayne@69: * Binary datetimes differ in a number of ways: the datatype, the unit, jpayne@69: * and the epoch (origin). We'll refer to these as time scales. For example: jpayne@69: * jpayne@69: * jpayne@69: * jpayne@69: * jpayne@69: * jpayne@69: * jpayne@69: * jpayne@69: * jpayne@69: * jpayne@69: * jpayne@69: * jpayne@69: * jpayne@69: * jpayne@69: * jpayne@69: * jpayne@69: * jpayne@69: * jpayne@69: * jpayne@69: * jpayne@69: * jpayne@69: * jpayne@69: * jpayne@69: * jpayne@69: * jpayne@69: * jpayne@69: * jpayne@69: * jpayne@69: * jpayne@69: * jpayne@69: * jpayne@69: * jpayne@69: * jpayne@69: * jpayne@69: * jpayne@69: * jpayne@69: * jpayne@69: * jpayne@69: * jpayne@69: * jpayne@69: * jpayne@69: * jpayne@69: * jpayne@69: * jpayne@69: * jpayne@69: * jpayne@69: * jpayne@69: * jpayne@69: * jpayne@69: * jpayne@69: * jpayne@69: * jpayne@69: * jpayne@69: * jpayne@69: * jpayne@69: * jpayne@69: * jpayne@69: * jpayne@69: * jpayne@69: * jpayne@69: * jpayne@69: * jpayne@69: * jpayne@69: * jpayne@69: * jpayne@69: * jpayne@69: * jpayne@69: * jpayne@69: * jpayne@69: * jpayne@69: * jpayne@69: * jpayne@69: * jpayne@69: * jpayne@69: * jpayne@69: * jpayne@69: * jpayne@69: * jpayne@69: * jpayne@69: *
Table 1: Binary Time Scales
SourceDatatypeUnitEpoch
UDTS_JAVA_TIMEint64_tmillisecondsJan 1, 1970
UDTS_UNIX_TIMEint32_t or int64_tsecondsJan 1, 1970
UDTS_ICU4C_TIMEdoublemillisecondsJan 1, 1970
UDTS_WINDOWS_FILE_TIMEint64_tticks (100 nanoseconds)Jan 1, 1601
UDTS_DOTNET_DATE_TIMEint64_tticks (100 nanoseconds)Jan 1, 0001
UDTS_MAC_OLD_TIMEint32_t or int64_tsecondsJan 1, 1904
UDTS_MAC_TIMEdoublesecondsJan 1, 2001
UDTS_EXCEL_TIME?daysDec 31, 1899
UDTS_DB2_TIME?daysDec 31, 1899
UDTS_UNIX_MICROSECONDS_TIMEint64_tmicrosecondsJan 1, 1970
jpayne@69: * jpayne@69: *

jpayne@69: * All of the epochs start at 00:00 am (the earliest possible time on the day in question), jpayne@69: * and are assumed to be UTC. jpayne@69: * jpayne@69: *

jpayne@69: * The ranges for different datatypes are given in the following table (all values in years). jpayne@69: * The range of years includes the entire range expressible with positive and negative jpayne@69: * values of the datatype. The range of years for double is the range that would be allowed jpayne@69: * without losing precision to the corresponding unit. jpayne@69: * jpayne@69: * jpayne@69: * jpayne@69: * jpayne@69: * jpayne@69: * jpayne@69: * jpayne@69: * jpayne@69: * jpayne@69: * jpayne@69: * jpayne@69: * jpayne@69: * jpayne@69: * jpayne@69: * jpayne@69: * jpayne@69: * jpayne@69: * jpayne@69: * jpayne@69: * jpayne@69: * jpayne@69: * jpayne@69: * jpayne@69: * jpayne@69: * jpayne@69: * jpayne@69: * jpayne@69: * jpayne@69: * jpayne@69: * jpayne@69: * jpayne@69: * jpayne@69: * jpayne@69: * jpayne@69: * jpayne@69: * jpayne@69: * jpayne@69: * jpayne@69: * jpayne@69: * jpayne@69: * jpayne@69: *
Unitsint64_tdoubleint32_t
1 sec5.84542x1011285,420,920.94136.10
1 millisecond584,542,046.09285,420.920.14
1 microsecond584,542.05285.420.00
100 nanoseconds (tick)58,454.2028.540.00
1 nanosecond584.54204610.28540.00
jpayne@69: * jpayne@69: *

jpayne@69: * These functions implement a universal time scale which can be used as a 'pivot', jpayne@69: * and provide conversion functions to and from all other major time scales. jpayne@69: * This datetimes to be converted to the pivot time, safely manipulated, jpayne@69: * and converted back to any other datetime time scale. jpayne@69: * jpayne@69: *

jpayne@69: * So what to use for this pivot? Java time has plenty of range, but cannot represent jpayne@69: * .NET System.DateTime values without severe loss of precision. ICU4C time addresses this by using a jpayne@69: * double that is otherwise equivalent to the Java time. However, there are disadvantages jpayne@69: * with doubles. They provide for much more graceful degradation in arithmetic operations. jpayne@69: * But they only have 53 bits of accuracy, which means that they will lose precision when jpayne@69: * converting back and forth to ticks. What would really be nice would be a jpayne@69: * long double (80 bits -- 64 bit mantissa), but that is not supported on most systems. jpayne@69: * jpayne@69: *

jpayne@69: * The Unix extended time uses a structure with two components: time in seconds and a jpayne@69: * fractional field (microseconds). However, this is clumsy, slow, and jpayne@69: * prone to error (you always have to keep track of overflow and underflow in the jpayne@69: * fractional field). BigDecimal would allow for arbitrary precision and arbitrary range, jpayne@69: * but we do not want to use this as the normal type, because it is slow and does not jpayne@69: * have a fixed size. jpayne@69: * jpayne@69: *

jpayne@69: * Because of these issues, we ended up concluding that the .NET framework's jpayne@69: * System.DateTime would be the best pivot. However, we use the full range jpayne@69: * allowed by the datatype, allowing for datetimes back to 29,000 BC and up to 29,000 AD. jpayne@69: * This time scale is very fine grained, does not lose precision, and covers a range that jpayne@69: * will meet almost all requirements. It will not handle the range that Java times do, jpayne@69: * but frankly, being able to handle dates before 29,000 BC or after 29,000 AD is of very limited interest. jpayne@69: * jpayne@69: */ jpayne@69: jpayne@69: /** jpayne@69: * UDateTimeScale values are used to specify the time scale used for jpayne@69: * conversion into or out if the universal time scale. jpayne@69: * jpayne@69: * @stable ICU 3.2 jpayne@69: */ jpayne@69: typedef enum UDateTimeScale { jpayne@69: /** jpayne@69: * Used in the JDK. Data is a Java long (int64_t). Value jpayne@69: * is milliseconds since January 1, 1970. jpayne@69: * jpayne@69: * @stable ICU 3.2 jpayne@69: */ jpayne@69: UDTS_JAVA_TIME = 0, jpayne@69: jpayne@69: /** jpayne@69: * Used on Unix systems. Data is int32_t or int64_t. Value jpayne@69: * is seconds since January 1, 1970. jpayne@69: * jpayne@69: * @stable ICU 3.2 jpayne@69: */ jpayne@69: UDTS_UNIX_TIME, jpayne@69: jpayne@69: /** jpayne@69: * Used in IUC4C. Data is a double. Value jpayne@69: * is milliseconds since January 1, 1970. jpayne@69: * jpayne@69: * @stable ICU 3.2 jpayne@69: */ jpayne@69: UDTS_ICU4C_TIME, jpayne@69: jpayne@69: /** jpayne@69: * Used in Windows for file times. Data is an int64_t. Value jpayne@69: * is ticks (1 tick == 100 nanoseconds) since January 1, 1601. jpayne@69: * jpayne@69: * @stable ICU 3.2 jpayne@69: */ jpayne@69: UDTS_WINDOWS_FILE_TIME, jpayne@69: jpayne@69: /** jpayne@69: * Used in the .NET framework's System.DateTime structure. Data is an int64_t. Value jpayne@69: * is ticks (1 tick == 100 nanoseconds) since January 1, 0001. jpayne@69: * jpayne@69: * @stable ICU 3.2 jpayne@69: */ jpayne@69: UDTS_DOTNET_DATE_TIME, jpayne@69: jpayne@69: /** jpayne@69: * Used in older Macintosh systems. Data is int32_t or int64_t. Value jpayne@69: * is seconds since January 1, 1904. jpayne@69: * jpayne@69: * @stable ICU 3.2 jpayne@69: */ jpayne@69: UDTS_MAC_OLD_TIME, jpayne@69: jpayne@69: /** jpayne@69: * Used in newer Macintosh systems. Data is a double. Value jpayne@69: * is seconds since January 1, 2001. jpayne@69: * jpayne@69: * @stable ICU 3.2 jpayne@69: */ jpayne@69: UDTS_MAC_TIME, jpayne@69: jpayne@69: /** jpayne@69: * Used in Excel. Data is an ?unknown?. Value jpayne@69: * is days since December 31, 1899. jpayne@69: * jpayne@69: * @stable ICU 3.2 jpayne@69: */ jpayne@69: UDTS_EXCEL_TIME, jpayne@69: jpayne@69: /** jpayne@69: * Used in DB2. Data is an ?unknown?. Value jpayne@69: * is days since December 31, 1899. jpayne@69: * jpayne@69: * @stable ICU 3.2 jpayne@69: */ jpayne@69: UDTS_DB2_TIME, jpayne@69: jpayne@69: /** jpayne@69: * Data is a long. Value is microseconds since January 1, 1970. jpayne@69: * Similar to Unix time (linear value from 1970) and struct timeval jpayne@69: * (microseconds resolution). jpayne@69: * jpayne@69: * @stable ICU 3.8 jpayne@69: */ jpayne@69: UDTS_UNIX_MICROSECONDS_TIME, jpayne@69: jpayne@69: #ifndef U_HIDE_DEPRECATED_API jpayne@69: /** jpayne@69: * The first unused time scale value. The limit of this enum jpayne@69: * @deprecated ICU 59 The numeric value may change over time, see ICU ticket #12420. jpayne@69: */ jpayne@69: UDTS_MAX_SCALE jpayne@69: #endif /* U_HIDE_DEPRECATED_API */ jpayne@69: jpayne@69: } UDateTimeScale; jpayne@69: jpayne@69: /** jpayne@69: * UTimeScaleValue values are used to specify the time scale values jpayne@69: * to utmscale_getTimeScaleValue. jpayne@69: * jpayne@69: * @see utmscale_getTimeScaleValue jpayne@69: * jpayne@69: * @stable ICU 3.2 jpayne@69: */ jpayne@69: typedef enum UTimeScaleValue { jpayne@69: /** jpayne@69: * The constant used to select the units vale jpayne@69: * for a time scale. jpayne@69: * jpayne@69: * @see utmscale_getTimeScaleValue jpayne@69: * jpayne@69: * @stable ICU 3.2 jpayne@69: */ jpayne@69: UTSV_UNITS_VALUE = 0, jpayne@69: jpayne@69: /** jpayne@69: * The constant used to select the epoch offset value jpayne@69: * for a time scale. jpayne@69: * jpayne@69: * @see utmscale_getTimeScaleValue jpayne@69: * jpayne@69: * @stable ICU 3.2 jpayne@69: */ jpayne@69: UTSV_EPOCH_OFFSET_VALUE=1, jpayne@69: jpayne@69: /** jpayne@69: * The constant used to select the minimum from value jpayne@69: * for a time scale. jpayne@69: * jpayne@69: * @see utmscale_getTimeScaleValue jpayne@69: * jpayne@69: * @stable ICU 3.2 jpayne@69: */ jpayne@69: UTSV_FROM_MIN_VALUE=2, jpayne@69: jpayne@69: /** jpayne@69: * The constant used to select the maximum from value jpayne@69: * for a time scale. jpayne@69: * jpayne@69: * @see utmscale_getTimeScaleValue jpayne@69: * jpayne@69: * @stable ICU 3.2 jpayne@69: */ jpayne@69: UTSV_FROM_MAX_VALUE=3, jpayne@69: jpayne@69: /** jpayne@69: * The constant used to select the minimum to value jpayne@69: * for a time scale. jpayne@69: * jpayne@69: * @see utmscale_getTimeScaleValue jpayne@69: * jpayne@69: * @stable ICU 3.2 jpayne@69: */ jpayne@69: UTSV_TO_MIN_VALUE=4, jpayne@69: jpayne@69: /** jpayne@69: * The constant used to select the maximum to value jpayne@69: * for a time scale. jpayne@69: * jpayne@69: * @see utmscale_getTimeScaleValue jpayne@69: * jpayne@69: * @stable ICU 3.2 jpayne@69: */ jpayne@69: UTSV_TO_MAX_VALUE=5, jpayne@69: jpayne@69: #ifndef U_HIDE_INTERNAL_API jpayne@69: /** jpayne@69: * The constant used to select the epoch plus one value jpayne@69: * for a time scale. jpayne@69: * jpayne@69: * NOTE: This is an internal value. DO NOT USE IT. May not jpayne@69: * actually be equal to the epoch offset value plus one. jpayne@69: * jpayne@69: * @see utmscale_getTimeScaleValue jpayne@69: * jpayne@69: * @internal ICU 3.2 jpayne@69: */ jpayne@69: UTSV_EPOCH_OFFSET_PLUS_1_VALUE=6, jpayne@69: jpayne@69: /** jpayne@69: * The constant used to select the epoch plus one value jpayne@69: * for a time scale. jpayne@69: * jpayne@69: * NOTE: This is an internal value. DO NOT USE IT. May not jpayne@69: * actually be equal to the epoch offset value plus one. jpayne@69: * jpayne@69: * @see utmscale_getTimeScaleValue jpayne@69: * jpayne@69: * @internal ICU 3.2 jpayne@69: */ jpayne@69: UTSV_EPOCH_OFFSET_MINUS_1_VALUE=7, jpayne@69: jpayne@69: /** jpayne@69: * The constant used to select the units round value jpayne@69: * for a time scale. jpayne@69: * jpayne@69: * NOTE: This is an internal value. DO NOT USE IT. jpayne@69: * jpayne@69: * @see utmscale_getTimeScaleValue jpayne@69: * jpayne@69: * @internal ICU 3.2 jpayne@69: */ jpayne@69: UTSV_UNITS_ROUND_VALUE=8, jpayne@69: jpayne@69: /** jpayne@69: * The constant used to select the minimum safe rounding value jpayne@69: * for a time scale. jpayne@69: * jpayne@69: * NOTE: This is an internal value. DO NOT USE IT. jpayne@69: * jpayne@69: * @see utmscale_getTimeScaleValue jpayne@69: * jpayne@69: * @internal ICU 3.2 jpayne@69: */ jpayne@69: UTSV_MIN_ROUND_VALUE=9, jpayne@69: jpayne@69: /** jpayne@69: * The constant used to select the maximum safe rounding value jpayne@69: * for a time scale. jpayne@69: * jpayne@69: * NOTE: This is an internal value. DO NOT USE IT. jpayne@69: * jpayne@69: * @see utmscale_getTimeScaleValue jpayne@69: * jpayne@69: * @internal ICU 3.2 jpayne@69: */ jpayne@69: UTSV_MAX_ROUND_VALUE=10, jpayne@69: jpayne@69: #endif /* U_HIDE_INTERNAL_API */ jpayne@69: jpayne@69: #ifndef U_HIDE_DEPRECATED_API jpayne@69: /** jpayne@69: * The number of time scale values, in other words limit of this enum. jpayne@69: * jpayne@69: * @see utmscale_getTimeScaleValue jpayne@69: * @deprecated ICU 59 The numeric value may change over time, see ICU ticket #12420. jpayne@69: */ jpayne@69: UTSV_MAX_SCALE_VALUE=11 jpayne@69: #endif /* U_HIDE_DEPRECATED_API */ jpayne@69: jpayne@69: } UTimeScaleValue; jpayne@69: jpayne@69: /** jpayne@69: * Get a value associated with a particular time scale. jpayne@69: * jpayne@69: * @param timeScale The time scale jpayne@69: * @param value A constant representing the value to get jpayne@69: * @param status The status code. Set to U_ILLEGAL_ARGUMENT_ERROR if arguments are invalid. jpayne@69: * @return - the value. jpayne@69: * jpayne@69: * @stable ICU 3.2 jpayne@69: */ jpayne@69: U_STABLE int64_t U_EXPORT2 jpayne@69: utmscale_getTimeScaleValue(UDateTimeScale timeScale, UTimeScaleValue value, UErrorCode *status); jpayne@69: jpayne@69: /* Conversion to 'universal time scale' */ jpayne@69: jpayne@69: /** jpayne@69: * Convert a int64_t datetime from the given time scale to the universal time scale. jpayne@69: * jpayne@69: * @param otherTime The int64_t datetime jpayne@69: * @param timeScale The time scale to convert from jpayne@69: * @param status The status code. Set to U_ILLEGAL_ARGUMENT_ERROR if the conversion is out of range. jpayne@69: * jpayne@69: * @return The datetime converted to the universal time scale jpayne@69: * jpayne@69: * @stable ICU 3.2 jpayne@69: */ jpayne@69: U_STABLE int64_t U_EXPORT2 jpayne@69: utmscale_fromInt64(int64_t otherTime, UDateTimeScale timeScale, UErrorCode *status); jpayne@69: jpayne@69: /* Conversion from 'universal time scale' */ jpayne@69: jpayne@69: /** jpayne@69: * Convert a datetime from the universal time scale to a int64_t in the given time scale. jpayne@69: * jpayne@69: * @param universalTime The datetime in the universal time scale jpayne@69: * @param timeScale The time scale to convert to jpayne@69: * @param status The status code. Set to U_ILLEGAL_ARGUMENT_ERROR if the conversion is out of range. jpayne@69: * jpayne@69: * @return The datetime converted to the given time scale jpayne@69: * jpayne@69: * @stable ICU 3.2 jpayne@69: */ jpayne@69: U_STABLE int64_t U_EXPORT2 jpayne@69: utmscale_toInt64(int64_t universalTime, UDateTimeScale timeScale, UErrorCode *status); jpayne@69: jpayne@69: #endif /* #if !UCONFIG_NO_FORMATTING */ jpayne@69: jpayne@69: #endif jpayne@69: