golden hour

/opt/alt/libicu65/usr/include/unicode

File/Folder	Size	Actions
alphaindex.h	26.48 KB
appendable.h	8.49 KB
basictz.h	9.15 KB
brkiter.h	27.8 KB
bytestream.h	9.6 KB
bytestrie.h	20.77 KB
bytestriebuilder.h	7.08 KB
calendar.h	105.74 KB
caniter.h	7.43 KB
casemap.h	25.33 KB
char16ptr.h	7.22 KB
chariter.h	24.05 KB
choicfmt.h	23.91 KB
coleitr.h	13.76 KB
coll.h	56.23 KB
compactdecimalformat.h	6.88 KB
curramt.h	3.76 KB
currpinf.h	7.3 KB
currunit.h	4.05 KB
datefmt.h	40.67 KB
dbbi.h	1.19 KB
dcfmtsym.h	20.13 KB
decimfmt.h	87.38 KB
docmain.h	6.97 KB
dtfmtsym.h	37.7 KB
dtintrv.h	3.84 KB
dtitvfmt.h	46.63 KB
dtitvinf.h	18.51 KB
dtptngen.h	25.08 KB
dtrule.h	8.68 KB
edits.h	20.74 KB
enumset.h	2.08 KB
errorcode.h	4.84 KB
fieldpos.h	8.69 KB
filteredbrk.h	5.37 KB
fmtable.h	24.42 KB
format.h	12.5 KB
formattedvalue.h	10.27 KB
fpositer.h	3.04 KB
gender.h	3.33 KB
gregocal.h	31.71 KB
icudataver.h	1.03 KB
icuplug.h	11.88 KB
idna.h	12.7 KB
listformatter.h	9.47 KB
localebuilder.h	11.27 KB
localematcher.h	22.5 KB
localpointer.h	19.69 KB
locdspnm.h	7.12 KB
locid.h	47.4 KB
measfmt.h	11.33 KB
measunit.h	93.31 KB
measure.h	4.32 KB
messagepattern.h	33.71 KB
msgfmt.h	44.11 KB
normalizer2.h	34.03 KB
normlzr.h	30.94 KB
nounit.h	2.69 KB
numberformatter.h	86.31 KB
numberrangeformatter.h	30.14 KB
numfmt.h	49.81 KB
numsys.h	7.19 KB
parseerr.h	3.08 KB
parsepos.h	5.56 KB
platform.h	28.08 KB
plurfmt.h	25.2 KB
plurrule.h	18.39 KB
ptypes.h	3.49 KB
putil.h	6.33 KB
rbbi.h	26.58 KB
rbnf.h	48.73 KB
rbtz.h	15.6 KB
regex.h	84.36 KB
region.h	9.18 KB
reldatefmt.h	22.62 KB
rep.h	9.37 KB
resbund.h	18.07 KB
schriter.h	6.32 KB
scientificnumberformatter.h	6.4 KB
search.h	22.22 KB
selfmt.h	14.3 KB
simpleformatter.h	12.59 KB
simpletz.h	45.44 KB
smpdtfmt.h	70.97 KB
sortkey.h	11.18 KB
std_string.h	1.05 KB
strenum.h	9.92 KB
stringoptions.h	5.79 KB
stringpiece.h	7.38 KB
stringtriebuilder.h	15.33 KB
stsearch.h	21.3 KB
symtable.h	4.27 KB
tblcoll.h	36.61 KB
timezone.h	41.02 KB
tmunit.h	3.38 KB
tmutamt.h	4.9 KB
tmutfmt.h	7.85 KB
translit.h	65.82 KB
tzfmt.h	42.89 KB
tznames.h	16.85 KB
tzrule.h	35.37 KB
tztrans.h	6.12 KB
ubidi.h	89.56 KB
ubiditransform.h	12.65 KB
ubrk.h	23.97 KB
ucal.h	56.9 KB
ucasemap.h	15.18 KB
ucat.h	5.36 KB
uchar.h	140.56 KB
ucharstrie.h	22.58 KB
ucharstriebuilder.h	7.21 KB
uchriter.h	13.2 KB
uclean.h	11.21 KB
ucnv.h	83.09 KB
ucnv_cb.h	6.59 KB
ucnv_err.h	20.99 KB
ucnvsel.h	6.14 KB
ucol.h	61.46 KB
ucoleitr.h	9.46 KB
uconfig.h	12.07 KB
ucpmap.h	5.53 KB
ucptrie.h	22.46 KB
ucsdet.h	14.67 KB
ucurr.h	16.12 KB
udat.h	60.88 KB
udata.h	15.56 KB
udateintervalformat.h	10.03 KB
udatpg.h	26.01 KB
udisplaycontext.h	5.89 KB
uenum.h	7.78 KB
ufieldpositer.h	4.36 KB
uformattable.h	10.94 KB
uformattedvalue.h	12.14 KB
ugender.h	2 KB
uidna.h	33.37 KB
uiter.h	22.77 KB
uldnames.h	10.45 KB
ulistformatter.h	8.83 KB
uloc.h	52.54 KB
ulocdata.h	11.26 KB
umachine.h	14.53 KB
umisc.h	1.33 KB
umsg.h	24.23 KB
umutablecptrie.h	8.24 KB
unifilt.h	3.96 KB
unifunct.h	4.04 KB
unimatch.h	6.1 KB
unirepl.h	3.38 KB
uniset.h	64.9 KB
unistr.h	170.43 KB
unorm.h	20.52 KB
unorm2.h	24.66 KB
unum.h	53.62 KB
unumberformatter.h	25.36 KB
unumsys.h	7.21 KB
uobject.h	10.68 KB
upluralrules.h	7.88 KB
uregex.h	72.05 KB
uregion.h	9.84 KB
ureldatefmt.h	17.26 KB
urename.h	130.97 KB
urep.h	5.38 KB
ures.h	36.54 KB
uscript.h	26.87 KB
usearch.h	38.12 KB
uset.h	40 KB
usetiter.h	9.55 KB
ushape.h	18 KB
uspoof.h	65.9 KB
usprep.h	8.14 KB
ustdio.h	38.54 KB
ustream.h	1.89 KB
ustring.h	72.47 KB
ustringtrie.h	3.15 KB
utext.h	58.13 KB
utf.h	7.86 KB
utf16.h	23.32 KB
utf32.h	763 B
utf8.h	30.96 KB
utf_old.h	45.83 KB
utmscale.h	13.78 KB
utrace.h	15.73 KB
utrans.h	25.52 KB
utypes.h	30.74 KB
uvernum.h	6.67 KB
uversion.h	6 KB
vtzone.h	20.3 KB

Edit: utmscale.h

// © 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,

#ifndef U_HIDE_DEPRECATED_API
    /**
     * The first unused time scale value. The limit of this enum
     * @deprecated ICU 59 The numeric value may change over time, see ICU ticket #12420.
     */
    UDTS_MAX_SCALE
#endif  /* U_HIDE_DEPRECATED_API */

} 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 */

#ifndef U_HIDE_DEPRECATED_API
    /**
     * The number of time scale values, in other words limit of this enum.
     * 
     * @see utmscale_getTimeScaleValue
     * @deprecated ICU 59 The numeric value may change over time, see ICU ticket #12420.
     */
    UTSV_MAX_SCALE_VALUE=11
#endif  /* U_HIDE_DEPRECATED_API */

} 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