1 January 1970, 00:00 UTC.  Note that the count of seconds does not
include any leap seconds; seconds are counted as if each UTC day has
exactly 86400 seconds.  Tcl responds to leap seconds by speeding or
slowing its clock by a tiny fraction for some minutes until it is
back in sync with UTC; its data model does not represent minutes that
have 59 or 61 seconds.
.TP
\fI\-now\fR
Instead of \fItimeVal\fR a non-integer option \fI\-now\fR can be used as
replacement for today, which is simply interpolated to the runt-time as value
of \fBclock seconds\fR. For example:
.sp
\fBclock format -now -f %a; # current day of the week\fR
.sp
\fBclock add -now 1 month; # next month\fR
.TP
\fIunit\fR
One of the words, \fBseconds\fR, \fBminutes\fR, \fBhours\fR,
\fBdays\fR, \fBweekdays\fR, \fBweeks\fR, \fBmonths\fR, or \fByears\fR.
Used in conjunction with \fIcount\fR to identify an interval of time,
for example, \fI3 seconds\fR or \fI1 year\fR.
.SS "OPTIONS"
.TP

string of the same meaning in the locale, to indicate whether \fB%Y\fR refers
to years before or after Year 1 of the Common Era.  On input, accepts
the string \fBB.C.E.\fR, \fBB.C.\fR, \fBC.E.\fR, \fBA.D.\fR, or the
abbreviation appropriate to the current locale, and uses it to fix
whether \fB%Y\fR refers to years before or after Year 1 of the
Common Era.
.TP
\fB%Es\fR
This affects similar to \fB%s\fR, but in opposition to \fB%s\fR it parses
or formats local seconds (not the posix seconds).
Because \fB%s\fR has the same precedence as \fB%s\fR (uniquely determines 
a point in time), it overrides all other input formats.
.TP
\fB%Ex\fR
On output, produces a locale-dependent representation of the date
in the locale's alternative calendar.  On input, matches
whatever \fB%Ex\fR produces.  The locale's alternative calendar need not
be the Gregorian calendar.
.TP
\fB%EX\fR

that \fB%Y\fR does not yield a year appropriate for use with the ISO8601
week number \fB%V\fR; programs should use \fB%G\fR for that purpose.
.TP
\fB%z\fR
On output, produces the current time zone, expressed in hours and
minutes east (+hhmm) or west (\-hhmm) of Greenwich. On input, accepts a
time zone specifier (see \fBTIME ZONES\fR below) that will be used to
determine the time zone.
determine the time zone (this token is optionally applicable on input, 
so the value is not mandatory and can be missing in input).
.TP
\fB%Z\fR
On output, produces the current time zone's name, possibly
translated to the given locale. On input, accepts a time zone
specifier (see \fBTIME ZONES\fR below) that will be used to determine the
time zone (token is also like \fB%z\fR optionally applicable on input).
time zone. This option should, in general, be used on input only when
This option should, in general, be used on input only when
parsing RFC822 dates. Other uses are fraught with ambiguity; for
instance, the string \fBBST\fR may represent British Summer Time or
Brazilian Standard Time. It is recommended that date/time strings for
use by computers use numeric time zones instead.
.TP
\fB%%\fR
On output, produces a literal

Using that time as the base, day-of-week specifications are added.
Next, relative specifications are used.  If a date or day is
specified, and no absolute or relative time is given, midnight is
used.  Finally, a correction is applied so that the correct hour of
the day is produced after allowing for daylight savings time
differences and the correct date is given when going from the end
of a long month to a short month.
.PP
The precedence of the applying of single tokens resp. which sequence will be
used by calculating of the time is complex, e. g. heavily dependent on the
precision of type of the token.
.sp
In example below the second date-string contains "next January", therefore
it results in next year but in January. And third date-string besides "January"
contains also additionally "Fri", so it results in the nearest Friday.
Thus both win before "385 days" resp. make it more precise, because of higher 
precision of this token types.
.CS
% clock format [clock scan "5 years 18 months 385 days" -base 0 -gmt 1] -gmt 1
Thu Jul 21 00:00:00 GMT 1977
% clock format [clock scan "5 years 18 months 385 days next January" -base 0 -gmt 1] -gmt 1
Sat Jan 21 00:00:00 GMT 1978
% clock format [clock scan "5 years 18 months 385 days next January Fri" -base 0 -gmt 1] -gmt 1
Fri Jan 27 00:00:00 GMT 1978
.CE
.SH "SEE ALSO"
msgcat(n)
.SH KEYWORDS
clock, date, time
.SH "COPYRIGHT"
Copyright (c) 2004 Kevin B. Kenny <kennykb@acm.org>. All rights reserved.
'\" Local Variables:
'\" mode: nroff
'\" End:

'\"
'\" Copyright (c) 2005 Sergey Brester aka sebres.
'\"
'\" See the file "license.terms" for information on usage and redistribution
'\" of this file, and for a DISCLAIMER OF ALL WARRANTIES.
'\"
.TH timerate n "" Tcl "Tcl Built-In Commands"
.so man.macros
.BS
'\" Note:  do not modify the .SH NAME line immediately below!
.SH NAME
timerate \- Time-related execution resp. performance measurement of a script
.SH SYNOPSIS
\fBtimerate \fIscript\fR \fI?time?\fR
.sp
\fBtimerate \fI?-direct?\fR \fI?-overhead double?\fR \fIscript\fR \fI?time?\fR
.sp
\fBtimerate \fI?-calibrate?\fR \fI?-direct?\fR \fIscript\fR \fI?time?\fR
.BE
.SH DESCRIPTION
.PP
The first and second form will evaluate \fIscript\fR until the interval
\fItime\fR given in milliseconds elapses, or for 1000 milliseconds (1 second)
if \fItime\fR is not specified. 
.sp
It will then return a canonical tcl-list of the form
.PP
.CS
\f0.095977 µs/# 52095836 # 10419167 #/sec 5000.000 nett-ms\fR
.CE
.PP
which indicates:
.IP \(bu
the average amount of time required per iteration, in microseconds (lindex $result 0)
.IP \(bu
the count how many times it was executed (lindex $result 2)
.IP \(bu
the estimated rate per second (lindex $result 4)
.IP \(bu
the estimated real execution time without measurement overhead (lindex $result 6)
.PP
Time is measured in elapsed time using heighest timer resolution as possible, not CPU time.
This command may be used to provide information as to how well the script or a tcl-command 
is performing and can help determine bottlenecks and fine-tune application performance.
.PP
\fI-calibrate\fR
.
To measure very fast scripts as exact as posible the calibration process
may be required.

This parameter used to calibrate \fBtimerate\fR calculating the estimated overhead 
of given \fIscript\fR as default overhead for further execution of \fBtimerate\fR.
It can take up to 10 seconds if parameter \fItime\fR is not specified.
.PP
\fI-overhead double\fR
.
This parameter used to supply the measurement overhead of single iteration 
(in microseconds) that should be ignored during whole evaluation process.
.PP
\fI-direct\fR
.
Causes direct execution per iteration (not compiled variant of evaluation used).
.PP
In opposition to \fBtime\fR the execution limited here by fixed time instead of 
repetition count.
Additionally the compiled variant of the script will be used during whole evaluation 
(as if it were part of a compiled \fBproc\fR), if parameter \fI-direct\fR is not specified.
Therefore it provides more precise results and prevents very long execution time 
by slow scripts resp. scripts with unknown speed.

.SH EXAMPLE
Estimate how fast it takes for a simple Tcl \fBfor\fR loop (including
operations on variable \fIi\fR) to count to a ten:
.PP
.CS
# calibrate:
timerate -calibrate {}
# measure:
timerate { for {set i 0} {$i<10} {incr i} {} } 5000
.CE
.PP
Estimate how fast it takes for a simple Tcl \fBfor\fR loop only (ignoring the 
overhead for operations on variable \fIi\fR) to count to a ten:
.PP
.CS
# calibrate for overhead of variable operations:
set i 0; timerate -calibrate {expr {$i<10}; incr i} 1000
# measure:
timerate { for {set i 0} {$i<10} {incr i} {} } 5000
.CE
.PP
Estimate the rate of calculating the hour using \fBclock format\fR only, ignoring 
overhead of the rest, without measurement how fast it takes for a whole script:
.PP
.CS
# calibrate:
timerate -calibrate {}
# estimate overhead:
set tm 0
set ovh [lindex [timerate { incr tm [expr {24*60*60}] }] 0]
# measure using esimated overhead:
set tm 0
timerate -overhead $ovh {
    clock format $tm -format %H
    incr tm [expr {24*60*60}]; # overhead for this is ignored
} 5000
.CE
.SH "SEE ALSO"
time(n)
.SH KEYWORDS
script, timerate, time
.\" Local Variables:
.\" mode: nroff
.\" End:

    {"pwd",		Tcl_PwdObjCmd,		NULL,			NULL,	0},
    {"read",		Tcl_ReadObjCmd,		NULL,			NULL,	CMD_IS_SAFE},
    {"seek",		Tcl_SeekObjCmd,		NULL,			NULL,	CMD_IS_SAFE},
    {"socket",		Tcl_SocketObjCmd,	NULL,			NULL,	0},
    {"source",		Tcl_SourceObjCmd,	NULL,			TclNRSourceObjCmd,	0},
    {"tell",		Tcl_TellObjCmd,		NULL,			NULL,	CMD_IS_SAFE},
    {"time",		Tcl_TimeObjCmd,		NULL,			NULL,	CMD_IS_SAFE},
    {"timerate",	Tcl_TimeRateObjCmd,	NULL,			NULL,	CMD_IS_SAFE},
    {"unload",		Tcl_UnloadObjCmd,	NULL,			NULL,	0},
    {"update",		Tcl_UpdateObjCmd,	NULL,			NULL,	CMD_IS_SAFE},
    {"vwait",		Tcl_VwaitObjCmd,	NULL,			NULL,	CMD_IS_SAFE},
    {NULL,		NULL,			NULL,			NULL,	0}
};

/*

/*
 * tclClock.c --
 *
 *	Contains the time and date related commands. This code is derived from
 *	the time and date facilities of TclX, by Mark Diekhans and Karl
 *	Lehenbauer.
 *
 * Copyright 1991-1995 Karl Lehenbauer and Mark Diekhans.
 * Copyright (c) 1995 Sun Microsystems, Inc.
 * Copyright (c) 2004 by Kevin B. Kenny. All rights reserved.
 * Copyright (c) 2015 by Sergey G. Brester aka sebres. All rights reserved.
 *
 * See the file "license.terms" for information on usage and redistribution of
 * this file, and for a DISCLAIMER OF ALL WARRANTIES.
 */

#include "tclInt.h"
#include "tclStrIdxTree.h"
#include "tclDate.h"
#include "tclCompile.h"

/*
 * Windows has mktime. The configurators do not check.
 */

#ifdef _WIN32
#define HAVE_MKTIME 1
#endif

/*
 * Constants
 */

#define JULIAN_DAY_POSIX_EPOCH		2440588
#define SECONDS_PER_DAY			86400
#define JULIAN_SEC_POSIX_EPOCH	      (((Tcl_WideInt) JULIAN_DAY_POSIX_EPOCH) \
					* SECONDS_PER_DAY)
#define FOUR_CENTURIES			146097	/* days */
#define JDAY_1_JAN_1_CE_JULIAN		1721424
#define JDAY_1_JAN_1_CE_GREGORIAN	1721426
#define ONE_CENTURY_GREGORIAN		36524	/* days */
#define FOUR_YEARS			1461	/* days */
#define ONE_YEAR			365	/* days */

/*
 * Table of the days in each month, leap and common years
 */

static const int hath[2][12] = {
    {31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31},
    {31, 29, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31}
};
static const int daysInPriorMonths[2][13] = {
    {0, 31, 59, 90, 120, 151, 181, 212, 243, 273, 304, 334, 365},
    {0, 31, 60, 91, 121, 152, 182, 213, 244, 274, 305, 335, 366}
};

/*
 * Enumeration of the string literals used in [clock]
 */

typedef enum ClockLiteral {
    LIT__NIL,
    LIT__DEFAULT_FORMAT,
    LIT_BCE,		LIT_C,
    LIT_CANNOT_USE_GMT_AND_TIMEZONE,
    LIT_CE,
    LIT_DAYOFMONTH,	LIT_DAYOFWEEK,		LIT_DAYOFYEAR,
    LIT_ERA,		LIT_GMT,		LIT_GREGORIAN,
    LIT_INTEGER_VALUE_TOO_LARGE,
    LIT_ISO8601WEEK,	LIT_ISO8601YEAR,
    LIT_JULIANDAY,	LIT_LOCALSECONDS,
    LIT_MONTH,
    LIT_SECONDS,	LIT_TZNAME,		LIT_TZOFFSET,
    LIT_YEAR,
    LIT__END
} ClockLiteral;
CLOCK_LITERAL_ARRAY(Literals);
static const char *const literals[] = {
    "",
    "%a %b %d %H:%M:%S %Z %Y",
    "BCE",		"C",
    "cannot use -gmt and -timezone in same call",
    "CE",
    "dayOfMonth",	"dayOfWeek",		"dayOfYear",
    "era",		":GMT",			"gregorian",
    "integer value too large to represent",
    "iso8601Week",	"iso8601Year",
    "julianDay",	"localSeconds",
    "month",
    "seconds",		"tzName",		"tzOffset",
    "year"
};

/*
 * Structure containing the client data for [clock]
 */

/* Msgcat literals for exact match (mcKey) */
typedef struct ClockClientData {
    size_t refCount;		/* Number of live references. */
    Tcl_Obj **literals;		/* Pool of object literals. */
CLOCK_LOCALE_LITERAL_ARRAY(MsgCtLiterals, "");
} ClockClientData;

/* Msgcat index literals prefixed with _IDX_, used for quick dictionary search */
/*
 * Structure containing the fields used in [clock format] and [clock scan]
 */
CLOCK_LOCALE_LITERAL_ARRAY(MsgCtLitIdxs, "_IDX_");

typedef struct TclDateFields {
    Tcl_WideInt seconds;	/* Time expressed in seconds from the Posix
				 * epoch */
    Tcl_WideInt localSeconds;	/* Local time expressed in nominal seconds
				 * from the Posix epoch */
    int tzOffset;		/* Time zone offset in seconds east of
				 * Greenwich */
    Tcl_Obj *tzName;		/* Time zone name */
    int julianDay;		/* Julian Day Number in local time zone */
    enum {BCE=1, CE=0} era;	/* Era */
    int gregorian;		/* Flag == 1 if the date is Gregorian */
    int year;			/* Year of the era */
    int dayOfYear;		/* Day of the year (1 January == 1) */
    int month;			/* Month number */
    int dayOfMonth;		/* Day of the month */
    int iso8601Year;		/* ISO8601 week-based year */
    int iso8601Week;		/* ISO8601 week number */
    int dayOfWeek;		/* Day of the week */
} TclDateFields;
static const char *const eras[] = { "CE", "BCE", NULL };

/*
 * Thread specific data block holding a 'struct tm' for the 'gmtime' and
 * 'localtime' library calls.
 */

static Tcl_ThreadDataKey tmKey;

/*
 * Mutex protecting 'gmtime', 'localtime' and 'mktime' calls and the statics
 * in the date parsing code.
 */

TCL_DECLARE_MUTEX(clockMutex)

/*
 * Function prototypes for local procedures in this file:
 */

static int		ConvertUTCToLocal(Tcl_Interp *,
			    TclDateFields *, Tcl_Obj *, int);
static int		ConvertUTCToLocalUsingTable(Tcl_Interp *,
			    TclDateFields *, int, Tcl_Obj *const[]);
			    TclDateFields *, int, Tcl_Obj *const[],
			    Tcl_WideInt rangesVal[2]);
static int		ConvertUTCToLocalUsingC(Tcl_Interp *,
			    TclDateFields *, int);
static int		ConvertLocalToUTC(Tcl_Interp *,
			    TclDateFields *, Tcl_Obj *, int);
static int		ConvertLocalToUTC(ClientData clientData, Tcl_Interp *,
			    TclDateFields *, Tcl_Obj *timezoneObj, int);
static int		ConvertLocalToUTCUsingTable(Tcl_Interp *,
			    TclDateFields *, int, Tcl_Obj *const[]);
			    TclDateFields *, int, Tcl_Obj *const[],
			    Tcl_WideInt rangesVal[2]);
static int		ConvertLocalToUTCUsingC(Tcl_Interp *,
			    TclDateFields *, int);
static Tcl_Obj *	LookupLastTransition(Tcl_Interp *, Tcl_WideInt,
			    int, Tcl_Obj *const *);
static int		ClockConfigureObjCmd(ClientData clientData,
			    Tcl_Interp *interp, int objc, Tcl_Obj *const objv[]);
static void		GetYearWeekDay(TclDateFields *, int);
static void		GetGregorianEraYearDay(TclDateFields *, int);
static void		GetMonthDay(TclDateFields *);
static void		GetJulianDayFromEraYearWeekDay(TclDateFields *, int);
static void		GetJulianDayFromEraYearMonthDay(TclDateFields *, int);
static int		IsGregorianLeapYear(TclDateFields *);
static int		WeekdayOnOrBefore(int, int);
static int		ClockClicksObjCmd(
			    ClientData clientData, Tcl_Interp *interp,
			    int objc, Tcl_Obj *const objv[]);
static int		ClockConvertlocaltoutcObjCmd(
			    ClientData clientData, Tcl_Interp *interp,
			    int objc, Tcl_Obj *const objv[]);

static int		ClockGetDateFields(ClientData clientData, 
			    Tcl_Interp *interp, TclDateFields *fields, 
			    Tcl_Obj *timezoneObj, int changeover);
static int		ClockGetdatefieldsObjCmd(
			    ClientData clientData, Tcl_Interp *interp,
			    int objc, Tcl_Obj *const objv[]);
static int		ClockGetjuliandayfromerayearmonthdayObjCmd(
			    ClientData clientData, Tcl_Interp *interp,
			    int objc, Tcl_Obj *const objv[]);
static int		ClockGetjuliandayfromerayearweekdayObjCmd(
			    ClientData clientData, Tcl_Interp *interp,
			    int objc, Tcl_Obj *const objv[]);
static int		ClockGetenvObjCmd(
			    ClientData clientData, Tcl_Interp *interp,
			    int objc, Tcl_Obj *const objv[]);
static int		ClockMicrosecondsObjCmd(
			    ClientData clientData, Tcl_Interp *interp,
			    int objc, Tcl_Obj *const objv[]);
static int		ClockMillisecondsObjCmd(
			    ClientData clientData, Tcl_Interp *interp,
			    int objc, Tcl_Obj *const objv[]);
static int		ClockSecondsObjCmd(
			    ClientData clientData, Tcl_Interp *interp,
			    int objc, Tcl_Obj *const objv[]);
static int		ClockFormatObjCmd(
			    ClientData clientData, Tcl_Interp *interp,
			    int objc, Tcl_Obj *const objv[]);
static int		ClockParseformatargsObjCmd(
static int		ClockScanObjCmd(
			    ClientData clientData, Tcl_Interp *interp,
			    int objc, Tcl_Obj *const objv[]);
static int		ClockSecondsObjCmd(
static int		ClockScanCommit(
			    ClientData clientData, register DateInfo *info,
			    register ClockFmtScnCmdArgs *opts);
static int		ClockFreeScan(
			    register DateInfo *info, 
			    Tcl_Obj *strObj, ClockFmtScnCmdArgs *opts);
static int		ClockCalcRelTime(
			    register DateInfo *info, ClockFmtScnCmdArgs *opts);
static int		ClockAddObjCmd(
			    ClientData clientData, Tcl_Interp *interp,
			    int objc, Tcl_Obj *const objv[]);
static struct tm *	ThreadSafeLocalTime(const time_t *);
static unsigned long	TzsetGetEpoch(void);
static void		TzsetIfNecessary(void);
static void		ClockDeleteCmdProc(ClientData);

/*
 * Structure containing description of "native" clock commands to create.
 */

struct ClockCommand {
    const char *name;		/* The tail of the command name. The full name
				 * is "::tcl::clock::<name>". When NULL marks
				 * the end of the table. */
    Tcl_ObjCmdProc *objCmdProc;	/* Function that implements the command. This
    Tcl_ObjCmdProc *objCmdProc; /* Function that implements the command. This
				 * will always have the ClockClientData sent
				 * to it, but may well ignore this data. */
    CompileProc *compileProc;	/* The compiler for the command. */
    ClientData clientData;	/* Any clientData to give the command (if NULL
    				 * a reference to ClockClientData will be sent) */
};

static const struct ClockCommand clockCommands[] = {
    {"add",		ClockAddObjCmd,		TclCompileBasicMin1ArgCmd, NULL},
    {"clicks",		ClockClicksObjCmd,	TclCompileClockClicksCmd,  NULL},
    {"format",		ClockFormatObjCmd,	TclCompileBasicMin1ArgCmd, NULL},
    { "getenv",			ClockGetenvObjCmd },
    { "Oldscan",		TclClockOldscanObjCmd },
    { "ConvertLocalToUTC",	ClockConvertlocaltoutcObjCmd },
    { "GetDateFields",		ClockGetdatefieldsObjCmd },
    { "GetJulianDayFromEraYearMonthDay",
		ClockGetjuliandayfromerayearmonthdayObjCmd },
    { "GetJulianDayFromEraYearWeekDay",
		ClockGetjuliandayfromerayearweekdayObjCmd },
    {"getenv",		ClockGetenvObjCmd,	TclCompileBasicMin1ArgCmd, NULL},
    {"microseconds",	ClockMicrosecondsObjCmd,TclCompileClockReadingCmd, INT2PTR(1)},
    {"milliseconds",	ClockMillisecondsObjCmd,TclCompileClockReadingCmd, INT2PTR(2)},
    {"scan",		ClockScanObjCmd,	TclCompileBasicMin1ArgCmd, NULL},
    {"seconds",		ClockSecondsObjCmd,	TclCompileClockReadingCmd, INT2PTR(3)},
    {"configure",	  ClockConfigureObjCmd,			NULL, NULL},
    {"Oldscan",		  TclClockOldscanObjCmd,		NULL, NULL},
    {"ConvertLocalToUTC", ClockConvertlocaltoutcObjCmd,		NULL, NULL},
    {"GetDateFields",	  ClockGetdatefieldsObjCmd,		NULL, NULL},
    {"GetJulianDayFromEraYearMonthDay",
		ClockGetjuliandayfromerayearmonthdayObjCmd,	NULL, NULL},
    {"GetJulianDayFromEraYearWeekDay",
		ClockGetjuliandayfromerayearweekdayObjCmd,	NULL, NULL},
    { "ParseFormatArgs",	ClockParseformatargsObjCmd },
    { NULL, NULL }
    {NULL, NULL, NULL, NULL}
};

/*
 *----------------------------------------------------------------------
 *
 * TclClockInit --
 *

TclClockInit(
    Tcl_Interp *interp)		/* Tcl interpreter */
{
    const struct ClockCommand *clockCmdPtr;
    char cmdName[50];		/* Buffer large enough to hold the string
				 *::tcl::clock::GetJulianDayFromEraYearMonthDay
				 * plus a terminating NUL. */
    Command         *cmdPtr;
    ClockClientData *data;
    int i;

    /* Structure of the 'clock' ensemble */

    static const EnsembleImplMap clockImplMap[] = {
	{"add",          NULL,                    TclCompileBasicMin1ArgCmd, NULL, NULL,       0},
	{"clicks",       ClockClicksObjCmd,       TclCompileClockClicksCmd,  NULL, NULL,       0},
	{"format",       NULL,                    TclCompileBasicMin1ArgCmd, NULL, NULL,       0},
	{"microseconds", ClockMicrosecondsObjCmd, TclCompileClockReadingCmd, NULL, INT2PTR(1), 0},
	{"milliseconds", ClockMillisecondsObjCmd, TclCompileClockReadingCmd, NULL, INT2PTR(2), 0},
	{"scan",         NULL,                    TclCompileBasicMin1ArgCmd, NULL, NULL      , 0},
	{"seconds",      ClockSecondsObjCmd,      TclCompileClockReadingCmd, NULL, INT2PTR(3), 0},
	{NULL,           NULL,                    NULL,                      NULL, NULL,       0}
    };

    /*
     * Safe interps get [::clock] as alias to a master, so do not need their
     * own copies of the support routines.
     */

    if (Tcl_IsSafe(interp)) {
	return;
    }

    /*
     * Create the client data, which is a refcounted literal pool.
     */

    data = ckalloc(sizeof(ClockClientData));
    data->refCount = 0;
    data->literals = ckalloc(LIT__END * sizeof(Tcl_Obj*));
    for (i = 0; i < LIT__END; ++i) {
	data->literals[i] = Tcl_NewStringObj(literals[i], -1);
	Tcl_IncrRefCount(data->literals[i]);
    }
	Tcl_InitObjRef(data->literals[i], Tcl_NewStringObj(Literals[i], -1));
    }
    data->mcLiterals = NULL;
    data->mcLitIdxs = NULL;
    data->LastTZEpoch = 0;
    data->currentYearCentury = ClockDefaultYearCentury;
    data->yearOfCenturySwitch = ClockDefaultCenturySwitch;
    data->SystemTimeZone = NULL;
    data->SystemSetupTZData = NULL;
    data->GMTSetupTimeZone = NULL;
    data->GMTSetupTZData = NULL;
    data->AnySetupTimeZone = NULL;
    data->AnySetupTZData = NULL;
    data->LastUnnormSetupTimeZone = NULL;
    data->LastSetupTimeZone = NULL;
    data->LastSetupTZData = NULL;

    data->CurrentLocale = NULL;
    data->CurrentLocaleDict = NULL;
    data->LastUnnormUsedLocale = NULL;
    data->LastUsedLocale = NULL;
    data->LastUsedLocaleDict = NULL;

    data->lastBase.timezoneObj = NULL;
    data->UTC2Local.timezoneObj = NULL;
    data->UTC2Local.tzName = NULL;
    data->Local2UTC.timezoneObj = NULL;

    /*
     * Install the commands.
     * TODO - Let Tcl_MakeEnsemble do this?
     */

#define TCL_CLOCK_PREFIX_LEN 14 /* == strlen("::tcl::clock::") */
    memcpy(cmdName, "::tcl::clock::", TCL_CLOCK_PREFIX_LEN);
    for (clockCmdPtr=clockCommands ; clockCmdPtr->name!=NULL ; clockCmdPtr++) {
    	ClientData clientData;

	strcpy(cmdName + TCL_CLOCK_PREFIX_LEN, clockCmdPtr->name);
	if (!(clientData = clockCmdPtr->clientData)) {
	    clientData = data;
	data->refCount++;
	Tcl_CreateObjCommand(interp, cmdName, clockCmdPtr->objCmdProc, data,
		ClockDeleteCmdProc);
    }

    /* Make the clock ensemble */

    TclMakeEnsemble(interp, "clock", clockImplMap);
	    data->refCount++;
	}
	cmdPtr = (Command *)Tcl_CreateObjCommand(interp, cmdName, 
		clockCmdPtr->objCmdProc, clientData,
		clockCmdPtr->clientData ? NULL : ClockDeleteCmdProc);
	cmdPtr->compileProc = clockCmdPtr->compileProc ? 
		clockCmdPtr->compileProc : TclCompileBasicMin0ArgCmd;
    }
}

/*
 *----------------------------------------------------------------------
 *
 * ClockConfigureClear --
 *
 *	Clean up cached resp. run-time storages used in clock commands.
 *
 *	Shared usage for clean-up (ClockDeleteCmdProc) and "configure -clear".
 *
 * Results:
 *	None.
 *
 *----------------------------------------------------------------------
 */

static void
ClockConfigureClear(
    ClockClientData *data)
{
    ClockFrmScnClearCaches();

    data->LastTZEpoch = 0;
    Tcl_UnsetObjRef(data->SystemTimeZone);
    Tcl_UnsetObjRef(data->SystemSetupTZData);
    Tcl_UnsetObjRef(data->GMTSetupTimeZone);
    Tcl_UnsetObjRef(data->GMTSetupTZData);
    Tcl_UnsetObjRef(data->AnySetupTimeZone);
    Tcl_UnsetObjRef(data->AnySetupTZData);
    Tcl_UnsetObjRef(data->LastUnnormSetupTimeZone);
    Tcl_UnsetObjRef(data->LastSetupTimeZone);
    Tcl_UnsetObjRef(data->LastSetupTZData);

    Tcl_UnsetObjRef(data->CurrentLocale);
    Tcl_UnsetObjRef(data->CurrentLocaleDict);
    Tcl_UnsetObjRef(data->LastUnnormUsedLocale);
    Tcl_UnsetObjRef(data->LastUsedLocale);
    Tcl_UnsetObjRef(data->LastUsedLocaleDict);

    Tcl_UnsetObjRef(data->lastBase.timezoneObj);
    Tcl_UnsetObjRef(data->UTC2Local.timezoneObj);
    Tcl_UnsetObjRef(data->UTC2Local.tzName);
    Tcl_UnsetObjRef(data->Local2UTC.timezoneObj);
}

/*
 *----------------------------------------------------------------------
 *
 * ClockDeleteCmdProc --
 *
 *	Remove a reference to the clock client data, and clean up memory
 *	when it's all gone.
 *
 * Results:
 *	None.
 *
 *----------------------------------------------------------------------
 */
static void
ClockDeleteCmdProc(
    ClientData clientData)	/* Opaque pointer to the client data */
{
    ClockClientData *data = clientData;
    int i;

    if (data->refCount-- <= 1) {
	for (i = 0; i < LIT__END; ++i) {
	    Tcl_DecrRefCount(data->literals[i]);
	}
	if (data->mcLiterals != NULL) {
	    for (i = 0; i < MCLIT__END; ++i) {
		Tcl_DecrRefCount(data->mcLiterals[i]);
	    }
	    data->mcLiterals = NULL;
	}
	if (data->mcLitIdxs != NULL) {
	    for (i = 0; i < MCLIT__END; ++i) {
		Tcl_DecrRefCount(data->mcLitIdxs[i]);
	    }
	    data->mcLitIdxs = NULL;
	}

	ClockConfigureClear(data);

	ckfree(data->literals);
	ckfree(data);
    }
}

/*
 *----------------------------------------------------------------------
 *
 * NormTimezoneObj --
 *
 *	Normalizes the timezone object (used for caching puposes).
 *
 *	If already cached time zone could be found, returns this
 *	object (last setup or last used, system (current) or gmt).
 *
 * Results:
 *	Normalized tcl object pointer.
 *
 *----------------------------------------------------------------------
 */

static inline Tcl_Obj *
NormTimezoneObj(
    ClockClientData *dataPtr,  /* Client data containing literal pool */
    Tcl_Obj *timezoneObj)
{
    const char *tz;
    if ( timezoneObj == dataPtr->LastUnnormSetupTimeZone
      && dataPtr->LastSetupTimeZone != NULL 
    ) {
	return dataPtr->LastSetupTimeZone;
    }
    if ( timezoneObj == dataPtr->LastSetupTimeZone
      || timezoneObj == dataPtr->literals[LIT_GMT]
      || timezoneObj == dataPtr->SystemTimeZone
      || timezoneObj == dataPtr->AnySetupTimeZone
    ) {
	return timezoneObj;
    }

    tz = TclGetString(timezoneObj);
    if (dataPtr->AnySetupTimeZone != NULL &&
	(timezoneObj == dataPtr->AnySetupTimeZone
	   || strcmp(tz, TclGetString(dataPtr->AnySetupTimeZone)) == 0
	)
    ) {
	timezoneObj = dataPtr->AnySetupTimeZone;
    }
    else
    if (dataPtr->SystemTimeZone != NULL &&
	(timezoneObj == dataPtr->SystemTimeZone
	   || strcmp(tz, TclGetString(dataPtr->SystemTimeZone)) == 0
	)
    ) {
	timezoneObj = dataPtr->SystemTimeZone;
    }
    else
    if (
	strcmp(tz, Literals[LIT_GMT]) == 0
    ) {
	timezoneObj = dataPtr->literals[LIT_GMT];
    }
    return timezoneObj;
}

/*
 *----------------------------------------------------------------------
 *
 * ClockGetSystemLocale --
 *
 *	Returns system locale.
 *
 *	Executes ::tcl::clock::GetSystemLocale in given interpreter.
 *
 * Results:
 *	Returns system locale tcl object.
 *
 *----------------------------------------------------------------------
 */

static inline Tcl_Obj *
ClockGetSystemLocale(
    ClockClientData *dataPtr,	/* Opaque pointer to literal pool, etc. */
    Tcl_Interp *interp)		/* Tcl interpreter */
{
    if (Tcl_EvalObjv(interp, 1, &dataPtr->literals[LIT_GETSYSTEMLOCALE], 0) != TCL_OK) {
	return NULL;
    }

    return Tcl_GetObjResult(interp);
}
/*
 *----------------------------------------------------------------------
 *
 * ClockGetCurrentLocale --
 *
 *	Returns current locale.
 *
 *	Executes ::tcl::clock::mclocale in given interpreter.
 *
 * Results:
 *	Returns current locale tcl object.
 *
 *----------------------------------------------------------------------
 */

static inline Tcl_Obj *
ClockGetCurrentLocale(
    ClockClientData *dataPtr,	/* Client data containing literal pool */
    Tcl_Interp *interp)		/* Tcl interpreter */
{   
    if (Tcl_EvalObjv(interp, 1, &dataPtr->literals[LIT_GETCURRENTLOCALE], 0) != TCL_OK) {
	return NULL;
    }

    Tcl_SetObjRef(dataPtr->CurrentLocale, Tcl_GetObjResult(interp));
    Tcl_UnsetObjRef(dataPtr->CurrentLocaleDict);

    return dataPtr->CurrentLocale;
}

/*
 *----------------------------------------------------------------------
 *
 * NormLocaleObj --
 *
 *	Normalizes the locale object (used for caching puposes).
 *
 *	If already cached locale could be found, returns this
 *	object (current, system (OS) or last used locales).
 *
 * Results:
 *	Normalized tcl object pointer.
 *
 *----------------------------------------------------------------------
 */

static Tcl_Obj *
NormLocaleObj(
    ClockClientData *dataPtr,	/* Client data containing literal pool */
    Tcl_Interp *interp,		/* Tcl interpreter */
    Tcl_Obj    *localeObj,
    Tcl_Obj   **mcDictObj)
{
    const char *loc;
    if ( localeObj == NULL || localeObj == dataPtr->CurrentLocale
      || localeObj == dataPtr->literals[LIT_C] 
      || localeObj == dataPtr->literals[LIT_CURRENT]
    ) {
	if (dataPtr->CurrentLocale == NULL) {
	    ClockGetCurrentLocale(dataPtr, interp);
	}
	*mcDictObj = dataPtr->CurrentLocaleDict;
	return dataPtr->CurrentLocale;
    }
    if ( localeObj == dataPtr->LastUsedLocale
      || localeObj == dataPtr->LastUnnormUsedLocale
    ) {
	*mcDictObj = dataPtr->LastUsedLocaleDict;
	return dataPtr->LastUsedLocale;
    }

    loc = TclGetString(localeObj);
    if ( dataPtr->CurrentLocale != NULL
      && ( localeObj == dataPtr->CurrentLocale
       || (localeObj->length == dataPtr->CurrentLocale->length
	  && strcmp(loc, TclGetString(dataPtr->CurrentLocale)) == 0
	)
      )
    ) {
	*mcDictObj = dataPtr->CurrentLocaleDict;
	localeObj = dataPtr->CurrentLocale;
    }
    else
    if ( dataPtr->LastUsedLocale != NULL
      && ( localeObj == dataPtr->LastUsedLocale
       || (localeObj->length == dataPtr->LastUsedLocale->length
	  && strcmp(loc, TclGetString(dataPtr->LastUsedLocale)) == 0
	)
      )
    ) {
	*mcDictObj = dataPtr->LastUsedLocaleDict;
	Tcl_SetObjRef(dataPtr->LastUnnormUsedLocale, localeObj);
	localeObj = dataPtr->LastUsedLocale;
    }
    else
    if (
	 (localeObj->length == 1 /* C */
	   && strncasecmp(loc, Literals[LIT_C], localeObj->length) == 0)
      || (localeObj->length == 7 /* current */
	   && strncasecmp(loc, Literals[LIT_CURRENT], localeObj->length) == 0)
    ) {
	if (dataPtr->CurrentLocale == NULL) {
	    ClockGetCurrentLocale(dataPtr, interp);
	}
	*mcDictObj = dataPtr->CurrentLocaleDict;
	localeObj = dataPtr->CurrentLocale;
    } 
    else 
    if (
	 (localeObj->length == 6 /* system */
	   && strncasecmp(loc, Literals[LIT_SYSTEM], localeObj->length) == 0)
    ) {
	Tcl_SetObjRef(dataPtr->LastUnnormUsedLocale, localeObj);
	localeObj = ClockGetSystemLocale(dataPtr, interp);
	Tcl_SetObjRef(dataPtr->LastUsedLocale, localeObj);
	*mcDictObj = NULL;
    } 
    else 
    {
	*mcDictObj = NULL;
    }
    return localeObj;
}

/*
 *----------------------------------------------------------------------
 *
 * ClockMCDict --
 *
 *	Retrieves a localized storage dictionary object for the given 
 *	locale object.
 *
 *	This corresponds with call `::tcl::clock::mcget locale`.
 *	Cached representation stored in options (for further access).
 *
 * Results:
 *	Tcl-object contains smart reference to msgcat dictionary.
 *
 *----------------------------------------------------------------------
 */

MODULE_SCOPE Tcl_Obj *
ClockMCDict(ClockFmtScnCmdArgs *opts)
{
    ClockClientData *dataPtr = opts->clientData;

    /* if dict not yet retrieved */
    if (opts->mcDictObj == NULL) {

	/* if locale was not yet used */
	if ( !(opts->flags & CLF_LOCALE_USED) ) {
	    
	    opts->localeObj = NormLocaleObj(opts->clientData, opts->interp,
		opts->localeObj, &opts->mcDictObj);
	    
	    if (opts->localeObj == NULL) {
		Tcl_SetResult(opts->interp,
		    "locale not specified and no default locale set", TCL_STATIC);
		Tcl_SetErrorCode(opts->interp, "CLOCK", "badOption", NULL);
		return NULL;
	    }
	    opts->flags |= CLF_LOCALE_USED;

	    /* check locale literals already available (on demand creation) */
	    if (dataPtr->mcLiterals == NULL) {
		int i;
		dataPtr->mcLiterals = ckalloc(MCLIT__END * sizeof(Tcl_Obj*));
		for (i = 0; i < MCLIT__END; ++i) {
		    Tcl_InitObjRef(dataPtr->mcLiterals[i], 
			Tcl_NewStringObj(MsgCtLiterals[i], -1));
		}
	    }
	}

	if (opts->mcDictObj == NULL) {
	    Tcl_Obj *callargs[2];
	    /* get msgcat dictionary - ::tcl::clock::mcget locale */
	    callargs[0] = dataPtr->literals[LIT_MCGET];
	    callargs[1] = opts->localeObj;

	    if (Tcl_EvalObjv(opts->interp, 2, callargs, 0) != TCL_OK) {
		return NULL;
	    }

	    opts->mcDictObj = Tcl_GetObjResult(opts->interp);
	    /* be sure that object reference not increases (dict changeable) */
	    if (opts->mcDictObj->refCount > 0) {
		/* smart reference (shared dict as object with no ref-counter) */
		opts->mcDictObj = Tcl_DictObjSmartRef(opts->interp, opts->mcDictObj);
	    }
	    if ( opts->localeObj == dataPtr->CurrentLocale ) {
		Tcl_SetObjRef(dataPtr->CurrentLocaleDict, opts->mcDictObj);
	    } else if ( opts->localeObj == dataPtr->LastUsedLocale ) {
		Tcl_SetObjRef(dataPtr->LastUsedLocaleDict, opts->mcDictObj);
	    } else {
		Tcl_SetObjRef(dataPtr->LastUsedLocale, opts->localeObj);
		Tcl_UnsetObjRef(dataPtr->LastUnnormUsedLocale);
		Tcl_SetObjRef(dataPtr->LastUsedLocaleDict, opts->mcDictObj);
	    }
	    Tcl_ResetResult(opts->interp);
	}
    }

    return opts->mcDictObj;
}

/*
 *----------------------------------------------------------------------
 *
 * ClockMCGet --
 *
 *	Retrieves a msgcat value for the given literal integer mcKey
 *	from localized storage (corresponding given locale object)
 *	by mcLiterals[mcKey] (e. g. MONTHS_FULL).
 *
 * Results:
 *	Tcl-object contains localized value.
 *
 *----------------------------------------------------------------------
 */

MODULE_SCOPE Tcl_Obj *
ClockMCGet(
    ClockFmtScnCmdArgs *opts, 
    int mcKey)
{
    ClockClientData *dataPtr = opts->clientData;

    Tcl_Obj *valObj = NULL;

    if (opts->mcDictObj == NULL) {
	ClockMCDict(opts);
	if (opts->mcDictObj == NULL)
	    return NULL;
    }

    Tcl_DictObjGet(opts->interp, opts->mcDictObj, 
	dataPtr->mcLiterals[mcKey], &valObj);

    return valObj; /* or NULL in obscure case if Tcl_DictObjGet failed */
}

/*
 *----------------------------------------------------------------------
 *
 * ClockMCGetIdx --
 *
 *	Retrieves an indexed msgcat value for the given literal integer mcKey
 *	from localized storage (corresponding given locale object)
 *	by mcLitIdxs[mcKey] (e. g. _IDX_MONTHS_FULL).
 *
 * Results:
 *	Tcl-object contains localized indexed value.
 *
 *----------------------------------------------------------------------
 */

MODULE_SCOPE Tcl_Obj *
ClockMCGetIdx(
    ClockFmtScnCmdArgs *opts, 
    int mcKey)
{
    ClockClientData *dataPtr = opts->clientData;

    Tcl_Obj *valObj = NULL;

    if (opts->mcDictObj == NULL) {
	ClockMCDict(opts);
	if (opts->mcDictObj == NULL)
	    return NULL;
    }

    /* try to get indices object */
    if (dataPtr->mcLitIdxs == NULL) {
	return NULL;
    }
    
    if (Tcl_DictObjGet(NULL, opts->mcDictObj, 
	dataPtr->mcLitIdxs[mcKey], &valObj) != TCL_OK
    ) {
	return NULL;
    }

    return valObj;
}

/*
 *----------------------------------------------------------------------
 *
 * ClockMCSetIdx --
 *
 *	Sets an indexed msgcat value for the given literal integer mcKey
 *	in localized storage (corresponding given locale object)
 *	by mcLitIdxs[mcKey] (e. g. _IDX_MONTHS_FULL).
 *
 * Results:
 *	Returns a standard Tcl result.
 *
 *----------------------------------------------------------------------
 */

MODULE_SCOPE int
ClockMCSetIdx(
    ClockFmtScnCmdArgs *opts, 
    int mcKey, Tcl_Obj *valObj)
{
    ClockClientData *dataPtr = opts->clientData;

    if (opts->mcDictObj == NULL) {
	ClockMCDict(opts);
	if (opts->mcDictObj == NULL)
	    return TCL_ERROR;
    }

    /* if literal storage for indices not yet created */
    if (dataPtr->mcLitIdxs == NULL) {
	int i;
	dataPtr->mcLitIdxs = ckalloc(MCLIT__END * sizeof(Tcl_Obj*));
	for (i = 0; i < MCLIT__END; ++i) {
	    Tcl_InitObjRef(dataPtr->mcLitIdxs[i], 
		Tcl_NewStringObj(MsgCtLitIdxs[i], -1));
	}
    }

    return Tcl_DictObjPut(opts->interp, opts->mcDictObj, 
	    dataPtr->mcLitIdxs[mcKey], valObj);
}

/*
 *----------------------------------------------------------------------
 *
 * ClockConfigureObjCmd --
 *
 *	This function is invoked to process the Tcl "clock configure" command.
 *
 * Usage:
 *	::tcl::clock::configure ?-option ?value??
 *
 * Results:
 *	Returns a standard Tcl result.
 *
 * Side effects:
 *	None.
 *
 *----------------------------------------------------------------------
 */

static int
ClockConfigureObjCmd(
    ClientData clientData,  /* Client data containing literal pool */
    Tcl_Interp *interp,	    /* Tcl interpreter */
    int objc,		    /* Parameter count */
    Tcl_Obj *const objv[])  /* Parameter vector */
{
    ClockClientData *dataPtr = clientData;
    
    static const char *const options[] = {
	"-system-tz",	  "-setup-tz",	  "-default-locale",
	"-clear",
	"-year-century",  "-century-switch",
	NULL
    };
    enum optionInd {
	CLOCK_SYSTEM_TZ,  CLOCK_SETUP_TZ, CLOCK_CURRENT_LOCALE,
	CLOCK_CLEAR_CACHE,
	CLOCK_YEAR_CENTURY, CLOCK_CENTURY_SWITCH,
	CLOCK_SETUP_GMT, CLOCK_SETUP_NOP
    };
    int optionIndex;		/* Index of an option. */
    int i;

    for (i = 1; i < objc; i++) {
	if (Tcl_GetIndexFromObj(interp, objv[i++], options, 
	    "option", 0, &optionIndex) != TCL_OK) {
	    Tcl_SetErrorCode(interp, "CLOCK", "badOption",
		    Tcl_GetString(objv[i-1]), NULL);
	    return TCL_ERROR;
	}
	switch (optionIndex) {
	case CLOCK_SYSTEM_TZ:
	if (1) {
	    /* validate current tz-epoch */
	    unsigned long lastTZEpoch = TzsetGetEpoch();
	    if (i < objc) {
		if (dataPtr->SystemTimeZone != objv[i]) {
		    Tcl_SetObjRef(dataPtr->SystemTimeZone, objv[i]);
		    Tcl_UnsetObjRef(dataPtr->SystemSetupTZData);
		}
		dataPtr->LastTZEpoch = lastTZEpoch;
	    } 
	    if (i+1 >= objc && dataPtr->SystemTimeZone != NULL 
			 && dataPtr->LastTZEpoch == lastTZEpoch) {
		Tcl_SetObjResult(interp, dataPtr->SystemTimeZone);
	    }
	}
	break;
	case CLOCK_SETUP_TZ:
	    if (i < objc) {
		/* differentiate GMT and system zones, because used often */
		Tcl_Obj *timezoneObj = NormTimezoneObj(dataPtr, objv[i]);
		Tcl_SetObjRef(dataPtr->LastUnnormSetupTimeZone, objv[i]);
		if (dataPtr->LastSetupTimeZone != timezoneObj) {
		    Tcl_SetObjRef(dataPtr->LastSetupTimeZone, timezoneObj);
		    Tcl_UnsetObjRef(dataPtr->LastSetupTZData);
		}
		if (timezoneObj == dataPtr->literals[LIT_GMT]) {
		    optionIndex = CLOCK_SETUP_GMT;
		} else if (timezoneObj == dataPtr->SystemTimeZone) {
		    optionIndex = CLOCK_SETUP_NOP;
		}
		switch (optionIndex) {
		case CLOCK_SETUP_GMT:
		    if (i < objc) {
			if (dataPtr->GMTSetupTimeZone != timezoneObj) {
			    Tcl_SetObjRef(dataPtr->GMTSetupTimeZone, timezoneObj);
			    Tcl_UnsetObjRef(dataPtr->GMTSetupTZData);
			}
		    }
		break;
		case CLOCK_SETUP_TZ:
		    if (i < objc) {
			if (dataPtr->AnySetupTimeZone != timezoneObj) {
			    Tcl_SetObjRef(dataPtr->AnySetupTimeZone, timezoneObj);
			    Tcl_UnsetObjRef(dataPtr->AnySetupTZData);
			}
		    } 
		break;
		}
	    }
	    if (i+1 >= objc && dataPtr->LastSetupTimeZone != NULL) {
		Tcl_SetObjResult(interp, dataPtr->LastSetupTimeZone);
	    }
	break;
	case CLOCK_CURRENT_LOCALE:
	    if (i < objc) {
		if (dataPtr->CurrentLocale != objv[i]) {
		    Tcl_SetObjRef(dataPtr->CurrentLocale, objv[i]);
		    Tcl_UnsetObjRef(dataPtr->CurrentLocaleDict);
		}
	    }
	    if (i+1 >= objc && dataPtr->CurrentLocale != NULL) {
		Tcl_SetObjResult(interp, dataPtr->CurrentLocale);
	    }
	break;
	case CLOCK_YEAR_CENTURY:
	    if (i < objc) {
		int year;
		if (TclGetIntFromObj(interp, objv[i], &year) != TCL_OK) {
		    return TCL_ERROR;
		}
		dataPtr->currentYearCentury = year;
		if (i+1 >= objc) {
		    Tcl_SetObjResult(interp, objv[i]);
		}
		continue;
	    }
	    if (i+1 >= objc) {
		Tcl_SetObjResult(interp, 
		    Tcl_NewIntObj(dataPtr->currentYearCentury));
	    }
	break;
	case CLOCK_CENTURY_SWITCH:
	    if (i < objc) {
		int year;
		if (TclGetIntFromObj(interp, objv[i], &year) != TCL_OK) {
		    return TCL_ERROR;
		}
		dataPtr->yearOfCenturySwitch = year;
		Tcl_SetObjResult(interp, objv[i]);
		continue;
	    }
	    if (i+1 >= objc) {
		Tcl_SetObjResult(interp, 
		    Tcl_NewIntObj(dataPtr->yearOfCenturySwitch));
	    }
	break;
	case CLOCK_CLEAR_CACHE:
	    ClockConfigureClear(dataPtr);
	break;
	}
    }

    return TCL_OK;
}

/*
 *----------------------------------------------------------------------
 *
 * ClockGetTZData --
 *
 *	Retrieves tzdata table for given normalized timezone.
 *
 * Results:
 *	Returns a tcl object with tzdata.
 *
 * Side effects:
 *	The tzdata can be cached in ClockClientData structure.
 *
 *----------------------------------------------------------------------
 */

static inline Tcl_Obj *
ClockGetTZData(
    ClientData clientData,	/* Opaque pointer to literal pool, etc. */
    Tcl_Interp *interp,		/* Tcl interpreter */
    Tcl_Obj *timezoneObj)	/* Name of the timezone */
{
    ClockClientData *dataPtr = clientData;
    Tcl_Obj **literals = dataPtr->literals;
    Tcl_Obj *ret, **out = NULL;

    /* if cached (if already setup this one) */
    if ( dataPtr->LastSetupTZData != NULL
      && ( timezoneObj == dataPtr->LastSetupTimeZone
	|| timezoneObj == dataPtr->LastUnnormSetupTimeZone
      )
    ) {
	return dataPtr->LastSetupTZData;
    }

    /* differentiate GMT and system zones, because used often */
    /* simple caching, because almost used the tz-data of last timezone
     */
    if (timezoneObj == dataPtr->SystemTimeZone) {
	if (dataPtr->SystemSetupTZData != NULL) {
	    return dataPtr->SystemSetupTZData;
	}
	out = &dataPtr->SystemSetupTZData;
    }
    else 
    if (timezoneObj == dataPtr->GMTSetupTimeZone) {
	if (dataPtr->GMTSetupTZData != NULL) {
	    return dataPtr->GMTSetupTZData;
	}
	out = &dataPtr->GMTSetupTZData;
    }
    else
    if (timezoneObj == dataPtr->AnySetupTimeZone) {
	if (dataPtr->AnySetupTZData != NULL) {
	    return dataPtr->AnySetupTZData;
	}
	out = &dataPtr->AnySetupTZData;
    }

    ret = Tcl_ObjGetVar2(interp, literals[LIT_TZDATA],
	timezoneObj, TCL_LEAVE_ERR_MSG);

    /* cache using corresponding slot and as last used */
    if (out != NULL) {
	Tcl_SetObjRef(*out, ret);
    }
    Tcl_SetObjRef(dataPtr->LastSetupTZData, ret);
    if (dataPtr->LastSetupTimeZone != timezoneObj) {
	Tcl_SetObjRef(dataPtr->LastSetupTimeZone, timezoneObj);
	Tcl_UnsetObjRef(dataPtr->LastUnnormSetupTimeZone);
    }
    return ret;
}

/*
 *----------------------------------------------------------------------
 *
 * ClockGetSystemTimeZone --
 *
 *	Returns system (current) timezone.
 *
 *	If system zone not yet cached, it executes ::tcl::clock::GetSystemTimeZone
 *	in given interpreter and caches its result.
 *
 * Results:
 *	Returns normalized timezone object.
 *
 *----------------------------------------------------------------------
 */

static Tcl_Obj *
ClockGetSystemTimeZone(
    ClientData clientData,	/* Opaque pointer to literal pool, etc. */
    Tcl_Interp *interp)		/* Tcl interpreter */
{
    ClockClientData *dataPtr = clientData;
    Tcl_Obj **literals;

    /* if known (cached and same epoch) - return now */
    if (dataPtr->SystemTimeZone != NULL 
	  && dataPtr->LastTZEpoch == TzsetGetEpoch()) {
	return dataPtr->SystemTimeZone;
    }

    Tcl_UnsetObjRef(dataPtr->SystemTimeZone);
    Tcl_UnsetObjRef(dataPtr->SystemSetupTZData);

    literals = dataPtr->literals;

    if (Tcl_EvalObjv(interp, 1, &literals[LIT_GETSYSTEMTIMEZONE], 0) != TCL_OK) {
	return NULL;
    }
    if (dataPtr->SystemTimeZone == NULL) {
	Tcl_SetObjRef(dataPtr->SystemTimeZone, Tcl_GetObjResult(interp));
    }
    return dataPtr->SystemTimeZone;
}

/*
 *----------------------------------------------------------------------
 *
 * ClockSetupTimeZone --
 *
 *	Sets up the timezone. Loads tzdata, etc.
 *
 * Results:
 *	Returns normalized timezone object.
 *
 *----------------------------------------------------------------------
 */

MODULE_SCOPE Tcl_Obj *
ClockSetupTimeZone(
    ClientData clientData,	/* Opaque pointer to literal pool, etc. */
    Tcl_Interp *interp,		/* Tcl interpreter */
    Tcl_Obj *timezoneObj)
{
    ClockClientData *dataPtr = clientData;
    Tcl_Obj **literals = dataPtr->literals;
    Tcl_Obj *callargs[2];

    /* if cached (if already setup this one) */
    if ( dataPtr->LastSetupTimeZone != NULL
      && ( timezoneObj == dataPtr->LastSetupTimeZone
	|| timezoneObj == dataPtr->LastUnnormSetupTimeZone
      )
    ) {
	return dataPtr->LastSetupTimeZone;
    }

    /* differentiate GMT and system zones, because used often and already set */
    timezoneObj = NormTimezoneObj(dataPtr, timezoneObj);
    if (   timezoneObj == dataPtr->GMTSetupTimeZone
	|| timezoneObj == dataPtr->SystemTimeZone
	|| timezoneObj == dataPtr->AnySetupTimeZone
    ) {
	return timezoneObj;
    }

    callargs[0] = literals[LIT_SETUPTIMEZONE];
    callargs[1] = timezoneObj;

    if (Tcl_EvalObjv(interp, 2, callargs, 0) == TCL_OK) {
	return dataPtr->LastSetupTimeZone;
    }
    return NULL;
}

/*
 *----------------------------------------------------------------------
 *
 * ClockFormatNumericTimeZone --
 *
 *	Formats a time zone as +hhmmss
 *
 * Parameters:
 *	z - Time zone in seconds east of Greenwich
 *
 * Results:
 *	Returns the time zone object (formatted in a numeric form)
 *
 * Side effects:
 *	None.
 *
 *----------------------------------------------------------------------
 */

Tcl_Obj * 
ClockFormatNumericTimeZone(int z) {
    char sign = '+';
    int h, m;
    if ( z < 0 ) {
	z = -z;
	sign = '-';
    }
    h = z / 3600;
    z %= 3600;
    m = z / 60;
    z %= 60;
    if (z != 0) {
	return Tcl_ObjPrintf("%c%02d%02d%02d", sign, h, m, z);
    }
    return Tcl_ObjPrintf("%c%02d%02d", sign, h, m);
}

/*
 *----------------------------------------------------------------------
 *
 * ClockConvertlocaltoutcObjCmd --
 *
 *	Tcl command that converts a UTC time to a local time by whatever means
 *	is available.
 *
 * Usage:
 *	::tcl::clock::ConvertUTCToLocal dictionary tzdata changeover
 *	::tcl::clock::ConvertUTCToLocal dictionary timezone changeover
 *
 * Parameters:
 *	dict - Dictionary containing a 'localSeconds' entry.
 *	tzdata - Time zone data
 *	timezone - Time zone
 *	changeover - Julian Day of the adoption of the Gregorian calendar.
 *
 * Results:
 *	Returns a standard Tcl result.
 *
 * Side effects:
 *	On success, sets the interpreter result to the given dictionary

    Tcl_Obj *secondsObj;
    Tcl_Obj *dict;
    int changeover;
    TclDateFields fields;
    int created = 0;
    int status;

    fields.tzName = NULL;
    /*
     * Check params and convert time.
     */

    if (objc != 4) {
	Tcl_WrongNumArgs(interp, 1, objv, "dict tzdata changeover");
	Tcl_WrongNumArgs(interp, 1, objv, "dict timezone changeover");
	return TCL_ERROR;
    }
    dict = objv[1];
    if (Tcl_DictObjGet(interp, dict, literals[LIT_LOCALSECONDS],
	    &secondsObj)!= TCL_OK) {
	return TCL_ERROR;
    }
    if (secondsObj == NULL) {
	Tcl_SetObjResult(interp, Tcl_NewStringObj("key \"localseconds\" not "
		"found in dictionary", -1));
	return TCL_ERROR;
    }
    if ((Tcl_GetWideIntFromObj(interp, secondsObj,
    if ((TclGetWideIntFromObj(interp, secondsObj,
	    &fields.localSeconds) != TCL_OK)
	|| (TclGetIntFromObj(interp, objv[3], &changeover) != TCL_OK)
	|| ConvertLocalToUTC(interp, &fields, objv[2], changeover)) {
	|| ConvertLocalToUTC(clientData, interp, &fields, objv[2], changeover)) {
	return TCL_ERROR;
    }

    /*
     * Copy-on-write; set the 'seconds' field in the dictionary and place the
     * modified dictionary in the interpreter result.
     */

 *
 * ClockGetdatefieldsObjCmd --
 *
 *	Tcl command that determines the values that [clock format] will use in
 *	formatting a date, and populates a dictionary with them.
 *
 * Usage:
 *	::tcl::clock::GetDateFields seconds tzdata changeover
 *	::tcl::clock::GetDateFields seconds timezone changeover
 *
 * Parameters:
 *	seconds - Time expressed in seconds from the Posix epoch.
 *	tzdata - Time zone data of the time zone in which time is to be
 *	timezone - Time zone in which time is to be expressed.
 *		 expressed.
 *	changeover - Julian Day Number at which the current locale adopted
 *		     the Gregorian calendar
 *
 * Results:
 *	Returns a dictonary populated with the fields:
 *		seconds - Seconds from the Posix epoch
 *		localSeconds - Nominal seconds from the Posix epoch in the

{
    TclDateFields fields;
    Tcl_Obj *dict;
    ClockClientData *data = clientData;
    Tcl_Obj *const *literals = data->literals;
    int changeover;

    fields.tzName = NULL;

    /*
     * Check params.
     */

    if (objc != 4) {
	Tcl_WrongNumArgs(interp, 1, objv, "seconds tzdata changeover");
	Tcl_WrongNumArgs(interp, 1, objv, "seconds timezone changeover");
	return TCL_ERROR;
    }
    if (Tcl_GetWideIntFromObj(interp, objv[1], &fields.seconds) != TCL_OK
    if (TclGetWideIntFromObj(interp, objv[1], &fields.seconds) != TCL_OK
	    || TclGetIntFromObj(interp, objv[3], &changeover) != TCL_OK) {
	return TCL_ERROR;
    }

    /*
     * fields.seconds could be an unsigned number that overflowed. Make sure
     * that it isn't.
     */

    if (objv[1]->typePtr == &tclBignumType) {
	Tcl_SetObjResult(interp, literals[LIT_INTEGER_VALUE_TOO_LARGE]);
	return TCL_ERROR;
    }

    /*
    /* Extract fields */
     * Convert UTC time to local.
     */

    if (ClockGetDateFields(clientData, interp, &fields, objv[2], 
    if (ConvertUTCToLocal(interp, &fields, objv[2], changeover) != TCL_OK) {
	  changeover) != TCL_OK) {
	return TCL_ERROR;
    }

    /*
     * Extract Julian day.
     */

    /* Make dict of fields */
    fields.julianDay = (int) ((fields.localSeconds + JULIAN_SEC_POSIX_EPOCH)
	    / SECONDS_PER_DAY);

    /*
     * Convert to Julian or Gregorian calendar.
     */

    GetGregorianEraYearDay(&fields, changeover);
    GetMonthDay(&fields);
    GetYearWeekDay(&fields, changeover);

    dict = Tcl_NewDictObj();
    Tcl_DictObjPut(NULL, dict, literals[LIT_LOCALSECONDS],
	    Tcl_NewWideIntObj(fields.localSeconds));
    Tcl_DictObjPut(NULL, dict, literals[LIT_SECONDS],
	    Tcl_NewWideIntObj(fields.seconds));
    Tcl_DictObjPut(NULL, dict, literals[LIT_TZNAME], fields.tzName);

	    Tcl_NewIntObj(fields.iso8601Year));
    Tcl_DictObjPut(NULL, dict, literals[LIT_ISO8601WEEK],
	    Tcl_NewIntObj(fields.iso8601Week));
    Tcl_DictObjPut(NULL, dict, literals[LIT_DAYOFWEEK],
	    Tcl_NewIntObj(fields.dayOfWeek));
    Tcl_SetObjResult(interp, dict);

    return TCL_OK;
}

/*
 *----------------------------------------------------------------------
 *
 * ClockGetDateFields --
 *
 *	Converts given UTC time (seconds in a TclDateFields structure) 
 *	to local time and determines the values that clock routines will 
 *	use in scanning or formatting a date.
 *
 * Results:
 *	Date-time values are stored in structure "fields".
 *	Returns a standard Tcl result.
 *
 *----------------------------------------------------------------------
 */

int
ClockGetDateFields(
    ClientData clientData,	/* Client data of the interpreter */
    Tcl_Interp *interp,		/* Tcl interpreter */
    TclDateFields *fields,	/* Pointer to result fields, where
				 * fields->seconds contains date to extract */
    Tcl_Obj *timezoneObj,	/* Time zone object or NULL for gmt */
    int changeover)		/* Julian Day Number */
{
    /*
     * Convert UTC time to local.
     */

    if (ConvertUTCToLocal(clientData, interp, fields, timezoneObj,
	    changeover) != TCL_OK) {
	return TCL_ERROR;
    }

    /*
     * Extract Julian day.
     */

    fields->julianDay = (int) ((fields->localSeconds + JULIAN_SEC_POSIX_EPOCH)
	    / SECONDS_PER_DAY);

    /*
     * Convert to Julian or Gregorian calendar.
     */

    GetGregorianEraYearDay(fields, changeover);
    GetMonthDay(fields);
    GetYearWeekDay(fields, changeover);

    return TCL_OK;
}

/*
 *----------------------------------------------------------------------
 *
 * ClockGetjuliandayfromerayearmonthdayObjCmd --

    Tcl_Obj *dict;
    ClockClientData *data = clientData;
    Tcl_Obj *const *literals = data->literals;
    int changeover;
    int copied = 0;
    int status;
    int era = 0;

    fields.tzName = NULL;

    /*
     * Check params.
     */

    if (objc != 3) {
	Tcl_WrongNumArgs(interp, 1, objv, "dict changeover");

    ClockClientData *data = clientData;
    Tcl_Obj *const *literals = data->literals;
    int changeover;
    int copied = 0;
    int status;
    int era = 0;

    fields.tzName = NULL;

    /*
     * Check params.
     */

    if (objc != 3) {
	Tcl_WrongNumArgs(interp, 1, objv, "dict changeover");
	return TCL_ERROR;

 *	in the interpreter result on failure.
 *
 *----------------------------------------------------------------------
 */

static int
ConvertLocalToUTC(
    ClientData clientData,	/* Client data of the interpreter */
    Tcl_Interp *interp,		/* Tcl interpreter */
    TclDateFields *fields,	/* Fields of the time */
    Tcl_Obj *tzdata,		/* Time zone data */
    Tcl_Obj *timezoneObj,	/* Time zone */
    int changeover)		/* Julian Day of the Gregorian transition */
{
    ClockClientData *dataPtr = clientData;
    Tcl_Obj *tzdata;		/* Time zone data */
    int rowc;			/* Number of rows in tzdata */
    Tcl_Obj **rowv;		/* Pointers to the rows */
    Tcl_WideInt seconds;

    /* fast phase-out for shared GMT-object (don't need to convert UTC 2 UTC) */
    if (timezoneObj == dataPtr->GMTSetupTimeZone && dataPtr->GMTSetupTimeZone != NULL) {
	fields->seconds = fields->localSeconds;
	fields->tzOffset = 0;
	return TCL_OK;
    }

    /*
     * Check cacheable conversion could be used
     * (last-period Local2UTC cache within the same TZ)
     */
    seconds = fields->localSeconds - dataPtr->Local2UTC.tzOffset;
    if ( timezoneObj == dataPtr->Local2UTC.timezoneObj
      && ( fields->localSeconds == dataPtr->Local2UTC.localSeconds
	|| ( seconds >= dataPtr->Local2UTC.rangesVal[0]
	  && seconds <	dataPtr->Local2UTC.rangesVal[1])
      )
      && changeover == dataPtr->Local2UTC.changeover
    ) {
	/* the same time zone and offset (UTC time inside the last minute) */
	fields->tzOffset = dataPtr->Local2UTC.tzOffset;
	fields->seconds = seconds;
	return TCL_OK;
    }

    /*
     * Check cacheable back-conversion could be used
     * (last-period UTC2Local cache within the same TZ)
     */
    seconds = fields->localSeconds - dataPtr->UTC2Local.tzOffset;
    if ( timezoneObj == dataPtr->UTC2Local.timezoneObj
      && ( seconds == dataPtr->UTC2Local.seconds
	|| ( seconds >= dataPtr->UTC2Local.rangesVal[0]
	  && seconds <	dataPtr->UTC2Local.rangesVal[1])
      )
      && changeover == dataPtr->UTC2Local.changeover
    ) {
	/* the same time zone and offset (UTC time inside the last minute) */
	fields->tzOffset = dataPtr->UTC2Local.tzOffset;
	fields->seconds = seconds;
	return TCL_OK;
    }

    /*
     * Unpack the tz data.
     */

    tzdata = ClockGetTZData(clientData, interp, timezoneObj);
    if (tzdata == NULL) {
	return TCL_ERROR;
    }

    if (TclListObjGetElements(interp, tzdata, &rowc, &rowv) != TCL_OK) {
	return TCL_ERROR;
    }

    /*
     * Special case: If the time zone is :localtime, the tzdata will be empty.
     * Use 'mktime' to convert the time to local
     */

    if (rowc == 0) {
	dataPtr->Local2UTC.rangesVal[0] = 0;
	dataPtr->Local2UTC.rangesVal[1] = 0;

	return ConvertLocalToUTCUsingC(interp, fields, changeover);
	if (ConvertLocalToUTCUsingC(interp, fields, changeover) != TCL_OK) {
	    return TCL_ERROR;
	};
    } else {
	return ConvertLocalToUTCUsingTable(interp, fields, rowc, rowv);
	if (ConvertLocalToUTCUsingTable(interp, fields, rowc, rowv, 
		dataPtr->Local2UTC.rangesVal) != TCL_OK) {
	    return TCL_ERROR;
	};
    }

    /* Cache the last conversion */
    Tcl_SetObjRef(dataPtr->Local2UTC.timezoneObj, timezoneObj);
    dataPtr->Local2UTC.localSeconds = fields->localSeconds;
    dataPtr->Local2UTC.changeover = changeover;
    dataPtr->Local2UTC.tzOffset = fields->tzOffset;

    return TCL_OK;
}

/*
 *----------------------------------------------------------------------
 *
 * ConvertLocalToUTCUsingTable --
 *

 */

static int
ConvertLocalToUTCUsingTable(
    Tcl_Interp *interp,		/* Tcl interpreter */
    TclDateFields *fields,	/* Time to convert, with 'seconds' filled in */
    int rowc,			/* Number of points at which time changes */
    Tcl_Obj *const rowv[])	/* Points at which time changes */
    Tcl_Obj *const rowv[],	/* Points at which time changes */
    Tcl_WideInt rangesVal[2])	/* Return bounds for time period */
{
    Tcl_Obj *row;
    int cellc;
    Tcl_Obj **cellv;
    int have[8];
    int nHave = 0;
    int i;

     * Saving Time transition.
     */

    found = 0;
    fields->tzOffset = 0;
    fields->seconds = fields->localSeconds;
    while (!found) {
	row = LookupLastTransition(interp, fields->seconds, rowc, rowv);
	row = LookupLastTransition(interp, fields->seconds, rowc, rowv,
		    rangesVal);
	if ((row == NULL)
		|| TclListObjGetElements(interp, row, &cellc,
		    &cellv) != TCL_OK
		|| TclGetIntFromObj(interp, cellv[1],
		    &fields->tzOffset) != TCL_OK) {
	    return TCL_ERROR;
	}

	    }
	    have[nHave++] = fields->tzOffset;
	}
	fields->seconds = fields->localSeconds - fields->tzOffset;
    }
    fields->tzOffset = have[i];
    fields->seconds = fields->localSeconds - fields->tzOffset;

#if 0
    /* currently unused, test purposes only */
    /*
     * Convert back from UTC, if local times are different - wrong local time
     * (local time seems to be in between DST-hole).
     */
    if (fields->tzOffset) {

	int corrOffset;
	Tcl_WideInt backCompVal;
	/* check DST-hole interval contains UTC time */
	TclGetWideIntFromObj(NULL, cellv[0], &backCompVal);
	if ( fields->seconds >= backCompVal - fields->tzOffset 
	  && fields->seconds <= backCompVal + fields->tzOffset
	) {
	    row = LookupLastTransition(interp, fields->seconds, rowc, rowv);
	    if (row == NULL ||
		    TclListObjGetElements(interp, row, &cellc, &cellv) != TCL_OK ||
		    TclGetIntFromObj(interp, cellv[1], &corrOffset) != TCL_OK) {
		return TCL_ERROR;
	    }
	    if (fields->localSeconds != fields->seconds + corrOffset) {
		Tcl_Panic("wrong local time %ld by LocalToUTC conversion,"
		    " local time seems to be in between DST-hole", 
		    fields->localSeconds);
		/* correcting offset * /
		fields->tzOffset -= corrOffset;
		fields->seconds += fields->tzOffset;
		*/
	    }
	}
    }
#endif

    return TCL_OK;
}

/*
 *----------------------------------------------------------------------
 *
 * ConvertLocalToUTCUsingC --

 *
 * Side effects:
 *	Populates the 'tzName' and 'tzOffset' fields.
 *
 *----------------------------------------------------------------------
 */

static int
MODULE_SCOPE int
ConvertUTCToLocal(
    ClientData clientData,	/* Client data of the interpreter */
    Tcl_Interp *interp,		/* Tcl interpreter */
    TclDateFields *fields,	/* Fields of the time */
    Tcl_Obj *tzdata,		/* Time zone data */
    Tcl_Obj *timezoneObj,	/* Time zone */
    int changeover)		/* Julian Day of the Gregorian transition */
{
    ClockClientData *dataPtr = clientData;
    Tcl_Obj *tzdata;		/* Time zone data */
    int rowc;			/* Number of rows in tzdata */
    Tcl_Obj **rowv;		/* Pointers to the rows */

    /* fast phase-out for shared GMT-object (don't need to convert UTC 2 UTC) */
    if (timezoneObj == dataPtr->GMTSetupTimeZone 
	&& dataPtr->GMTSetupTimeZone != NULL 
	&& dataPtr->GMTSetupTZData != NULL
    ) {
	fields->localSeconds = fields->seconds;
	fields->tzOffset = 0;
	if ( TclListObjGetElements(interp, dataPtr->GMTSetupTZData, &rowc, &rowv) != TCL_OK
	  || Tcl_ListObjIndex(interp, rowv[0], 3, &fields->tzName) != TCL_OK) {
	    return TCL_ERROR;
	}
	Tcl_IncrRefCount(fields->tzName);
	return TCL_OK;
    }

    /*
     * Check cacheable conversion could be used
     * (last-period UTC2Local cache within the same TZ)
     */
    if ( timezoneObj == dataPtr->UTC2Local.timezoneObj
      && ( fields->seconds == dataPtr->UTC2Local.seconds
	|| ( fields->seconds >= dataPtr->UTC2Local.rangesVal[0]
	  && fields->seconds <	dataPtr->UTC2Local.rangesVal[1])
      )
      && changeover == dataPtr->UTC2Local.changeover
    ) {
	/* the same time zone and offset (UTC time inside the last minute) */
	Tcl_SetObjRef(fields->tzName, dataPtr->UTC2Local.tzName);
	fields->tzOffset = dataPtr->UTC2Local.tzOffset;
	fields->localSeconds = fields->seconds + fields->tzOffset;
	return TCL_OK;
    }

    /*
     * Unpack the tz data.
     */

    tzdata = ClockGetTZData(clientData, interp, timezoneObj);
    if (tzdata == NULL) {
	return TCL_ERROR;
    }

    if (TclListObjGetElements(interp, tzdata, &rowc, &rowv) != TCL_OK) {
	return TCL_ERROR;
    }

    /*
     * Special case: If the time zone is :localtime, the tzdata will be empty.
     * Use 'localtime' to convert the time to local
     */

    if (rowc == 0) {
	dataPtr->UTC2Local.rangesVal[0] = 0;
	dataPtr->UTC2Local.rangesVal[1] = 0;

	return ConvertUTCToLocalUsingC(interp, fields, changeover);
	if (ConvertUTCToLocalUsingC(interp, fields, changeover) != TCL_OK) {
	    return TCL_ERROR;
	}
    } else {
	return ConvertUTCToLocalUsingTable(interp, fields, rowc, rowv);
    }
	if (ConvertUTCToLocalUsingTable(interp, fields, rowc, rowv, 
		dataPtr->UTC2Local.rangesVal) != TCL_OK) {
	    return TCL_ERROR;
	}
    }

    /* Cache the last conversion */
    Tcl_SetObjRef(dataPtr->UTC2Local.timezoneObj, timezoneObj);
    dataPtr->UTC2Local.seconds = fields->seconds;
    dataPtr->UTC2Local.changeover = changeover;
    dataPtr->UTC2Local.tzOffset = fields->tzOffset;
    Tcl_SetObjRef(dataPtr->UTC2Local.tzName, fields->tzName);
    return TCL_OK;
}

/*
 *----------------------------------------------------------------------
 *
 * ConvertUTCToLocalUsingTable --
 *

static int
ConvertUTCToLocalUsingTable(
    Tcl_Interp *interp,		/* Tcl interpreter */
    TclDateFields *fields,	/* Fields of the date */
    int rowc,			/* Number of rows in the conversion table
				 * (>= 1) */
    Tcl_Obj *const rowv[])	/* Rows of the conversion table */
    Tcl_Obj *const rowv[],	/* Rows of the conversion table */
    Tcl_WideInt rangesVal[2])	/* Return bounds for time period */
{
    Tcl_Obj *row;		/* Row containing the current information */
    int cellc;			/* Count of cells in the row (must be 4) */
    Tcl_Obj **cellv;		/* Pointers to the cells */

    /*
     * Look up the nearest transition time.
     */

    row = LookupLastTransition(interp, fields->seconds, rowc, rowv);
    row = LookupLastTransition(interp, fields->seconds, rowc, rowv, rangesVal);
    if (row == NULL ||
	    TclListObjGetElements(interp, row, &cellc, &cellv) != TCL_OK ||
	    TclGetIntFromObj(interp, cellv[1], &fields->tzOffset) != TCL_OK) {
	return TCL_ERROR;
    }

    /*
     * Convert the time.
     */

    fields->tzName = cellv[3];
    Tcl_SetObjRef(fields->tzName, cellv[3]);
    Tcl_IncrRefCount(fields->tzName);
    fields->localSeconds = fields->seconds + fields->tzOffset;
    return TCL_OK;
}

/*
 *----------------------------------------------------------------------
 *

    sprintf(buffer+1, "%02d", diff / 3600);
    diff %= 3600;
    sprintf(buffer+3, "%02d", diff / 60);
    diff %= 60;
    if (diff > 0) {
	sprintf(buffer+5, "%02d", diff);
    }
    fields->tzName = Tcl_NewStringObj(buffer, -1);
    Tcl_SetObjRef(fields->tzName, Tcl_NewStringObj(buffer, -1));
    Tcl_IncrRefCount(fields->tzName);
    return TCL_OK;
}

/*
 *----------------------------------------------------------------------
 *
 * LookupLastTransition --
 *
 *	Given a UTC time and a tzdata array, looks up the last transition on
 *	or before the given time.
 *
 * Results:
 *	Returns a pointer to the row, or NULL if an error occurs.
 *
 *----------------------------------------------------------------------
 */

static Tcl_Obj *
MODULE_SCOPE Tcl_Obj *
LookupLastTransition(
    Tcl_Interp *interp,		/* Interpreter for error messages */
    Tcl_WideInt tick,		/* Time from the epoch */
    int rowc,			/* Number of rows of tzdata */
    Tcl_Obj *const *rowv)	/* Rows in tzdata */
    Tcl_Obj *const *rowv,	/* Rows in tzdata */
    Tcl_WideInt rangesVal[2])	/* Return bounds for time period */
{
    int l;
    int l = 0;
    int u;
    Tcl_Obj *compObj;
    Tcl_WideInt compVal;
    Tcl_WideInt compVal, fromVal = tick, toVal = tick;

    /*
     * Examine the first row to make sure we're in bounds.
     */

    if (Tcl_ListObjIndex(interp, rowv[0], 0, &compObj) != TCL_OK
	    || Tcl_GetWideIntFromObj(interp, compObj, &compVal) != TCL_OK) {
	    || TclGetWideIntFromObj(interp, compObj, &compVal) != TCL_OK) {
	return NULL;
    }

    /*
     * Bizarre case - first row doesn't begin at MIN_WIDE_INT. Return it
     * anyway.
     */

    if (tick < compVal) {
	return rowv[0];
	goto done;
    }

    /*
     * Binary-search to find the transition.
     */

    l = 0;
    u = rowc-1;
    while (l < u) {
	int m = (l + u + 1) / 2;

	if (Tcl_ListObjIndex(interp, rowv[m], 0, &compObj) != TCL_OK ||
		Tcl_GetWideIntFromObj(interp, compObj, &compVal) != TCL_OK) {
		TclGetWideIntFromObj(interp, compObj, &compVal) != TCL_OK) {
	    return NULL;
	}
	if (tick >= compVal) {
	    l = m;
	    fromVal = compVal;
	} else {
	    u = m-1;
	    toVal = compVal;
	}
    }

done:

    if (rangesVal) {
	rangesVal[0] = fromVal;
	rangesVal[1] = toVal;
    }
    return rowv[l];
}

/*
 *----------------------------------------------------------------------
 *
 * GetYearWeekDay --

GetYearWeekDay(
    TclDateFields *fields,	/* Date to convert, must have 'julianDay' */
    int changeover)		/* Julian Day Number of the Gregorian
				 * transition */
{
    TclDateFields temp;
    int dayOfFiscalYear;

    temp.tzName = NULL;

    /*
     * Find the given date, minus three days, plus one year. That date's
     * iso8601 year is an upper bound on the ISO8601 year of the given date.
     */

    temp.julianDay = fields->julianDay - 3;

 *
 * Side effects:
 *	Stores 'julianDay' in the fields.
 *
 *----------------------------------------------------------------------
 */

static void
MODULE_SCOPE void
GetJulianDayFromEraYearWeekDay(
    TclDateFields *fields,	/* Date to convert */
    int changeover)		/* Julian Day Number of the Gregorian
				 * transition */
{
    int firstMonday;		/* Julian day number of week 1, day 1 in the
				 * given year */
    TclDateFields firstWeek;

    firstWeek.tzName = NULL;

    /*
     * Find January 4 in the ISO8601 year, which will always be in week 1.
     */

    firstWeek.era = fields->era;
    firstWeek.year = fields->iso8601Year;

 *
 * Side effects:
 *	Stores day number in 'julianDay'
 *
 *----------------------------------------------------------------------
 */

static void
MODULE_SCOPE void
GetJulianDayFromEraYearMonthDay(
    TclDateFields *fields,	/* Date to convert */
    int changeover)		/* Gregorian transition date as a Julian Day */
{
    int year, ym1, month, mm1, q, r, ym1o4, ym1o100, ym1o400;

    if (fields->era == BCE) {

    ym1o4 = ym1 / 4;
#else
    /*
     * Have to make sure quotient is truncated towards 0 when negative.
     * See above bug for details. The casts are necessary.
     */
    if (ym1 >= 0)
        ym1o4 = ym1 / 4;
	ym1o4 = ym1 / 4;
    else {
        ym1o4 = - (int) (((unsigned int) -ym1) / 4);
	ym1o4 = - (int) (((unsigned int) -ym1) / 4);
    }
#endif
    if (ym1 % 4 < 0) {
	ym1o4--;
    }
    ym1o100 = ym1 / 100;
    if (ym1 % 100 < 0) {

		+ ym1o4;
    }
}

/*
 *----------------------------------------------------------------------
 *
 * GetJulianDayFromEraYearDay --
 *
 *	Given era, year, and dayOfYear (in TclDateFields), and the
 *	Gregorian transition date, computes the Julian Day Number.
 *
 * Results:
 *	None.
 *
 * Side effects:
 *	Stores day number in 'julianDay'
 *
 *----------------------------------------------------------------------
 */


MODULE_SCOPE void
GetJulianDayFromEraYearDay(
    TclDateFields *fields,	/* Date to convert */
    int changeover)		/* Gregorian transition date as a Julian Day */
{
    int year, ym1;

    /* Get absolute year number from the civil year */
    if (fields->era == BCE) {
	year = 1 - fields->year;
    } else {
	year = fields->year;
    }

    ym1 = year - 1;

    /* Try the Gregorian calendar first. */
    fields->gregorian = 1;
    fields->julianDay =
	1721425
	+ fields->dayOfYear
	+ ( 365 * ym1 )
	+ ( ym1 / 4 )
	- ( ym1 / 100 )
	+ ( ym1 / 400 );

    /* If the date is before the Gregorian change, use the Julian calendar. */

    if ( fields->julianDay < changeover ) {
	fields->gregorian = 0;
	fields->julianDay =
	    1721423
	    + fields->dayOfYear
	    + ( 365 * ym1 )
	    + ( ym1 / 4 );
    }
}
/*
 *----------------------------------------------------------------------
 *
 * IsGregorianLeapYear --
 *
 *	Tests whether a given year is a leap year, in either Julian or
 *	Gregorian calendar.
 *
 * Results:
 *	Returns 1 for a leap year, 0 otherwise.
 *
 *----------------------------------------------------------------------
 */

static int
MODULE_SCOPE int
IsGregorianLeapYear(
    TclDateFields *fields)	/* Date to test */
{
    int year;
    int year = fields->year;

    if (fields->era == BCE) {
	year = 1 - fields->year;
	year = 1 - year;
    } else {
	year = fields->year;
    }
    if (year%4 != 0) {
	return 0;
    } else if (!(fields->gregorian)) {
	return 1;
    } else if (year%400 == 0) {
	return 1;

    case 2:
	if (Tcl_GetIndexFromObj(interp, objv[1], clicksSwitches, "option", 0,
		&index) != TCL_OK) {
	    return TCL_ERROR;
	}
	break;
    default:
	Tcl_WrongNumArgs(interp, 1, objv, "?-switch?");
	Tcl_WrongNumArgs(interp, 0, NULL, "clock clicks ?-switch?");
	return TCL_ERROR;
    }

    switch (index) {
    case CLICKS_MILLIS:
	Tcl_GetTime(&now);
	clicks = (Tcl_WideInt) now.sec * 1000 + now.usec / 1000;
	break;
    case CLICKS_NATIVE:
#ifdef TCL_WIDE_CLICKS
	clicks = TclpGetWideClicks();
#else
	clicks = (Tcl_WideInt) TclpGetClicks();
#endif
	break;
    case CLICKS_MICROS:
	Tcl_GetTime(&now);
	clicks = ((Tcl_WideInt) now.sec * 1000000) + now.usec;
	clicks = TclpGetMicroseconds();
	break;
    }

    Tcl_SetObjResult(interp, Tcl_NewWideIntObj(clicks));
    return TCL_OK;
}


    Tcl_Interp *interp,		/* Tcl interpreter */
    int objc,			/* Parameter count */
    Tcl_Obj *const *objv)	/* Parameter values */
{
    Tcl_Time now;

    if (objc != 1) {
	Tcl_WrongNumArgs(interp, 1, objv, NULL);
	Tcl_WrongNumArgs(interp, 0, NULL, "clock milliseconds");
	return TCL_ERROR;
    }
    Tcl_GetTime(&now);
    Tcl_SetObjResult(interp, Tcl_NewWideIntObj((Tcl_WideInt)
	    now.sec * 1000 + now.usec / 1000));
    return TCL_OK;
}

int
ClockMicrosecondsObjCmd(
    ClientData clientData,	/* Client data is unused */
    Tcl_Interp *interp,		/* Tcl interpreter */
    int objc,			/* Parameter count */
    Tcl_Obj *const *objv)	/* Parameter values */
{
    Tcl_Time now;

    if (objc != 1) {
	Tcl_WrongNumArgs(interp, 1, objv, NULL);
	Tcl_WrongNumArgs(interp, 0, NULL, "clock microseconds");
	return TCL_ERROR;
    }
    Tcl_GetTime(&now);
    Tcl_SetObjResult(interp, Tcl_NewWideIntObj(
    Tcl_SetObjResult(interp, Tcl_NewWideIntObj(TclpGetMicroseconds()));
	    ((Tcl_WideInt) now.sec * 1000000) + now.usec));
    return TCL_OK;
}

static inline void
ClockInitFmtScnArgs(
    ClientData clientData,
    Tcl_Interp *interp,
    ClockFmtScnCmdArgs *opts)
{
    memset(opts, 0, sizeof(*opts));
    opts->clientData = clientData;
    opts->interp = interp;
}

/*
 *-----------------------------------------------------------------------------
 *
 * ClockParseformatargsObjCmd --
 * ClockParseFmtScnArgs --
 *
 *	Parses the arguments for [clock format].
 *	Parses the arguments for [clock scan] and [clock format].
 *
 * Results:
 *	Returns a standard Tcl result, whose value is a four-element list
 *	comprising the time format, the locale, and the timezone.
 *	Returns a standard Tcl result, and stores parsed options
 *	(format, the locale, timezone and base) in structure "opts".
 *
 * This function exists because the loop that parses the [clock format]
 * options is a known performance "hot spot", and is implemented in an effort
 * to speed that particular code up.
 *
 *-----------------------------------------------------------------------------
 */

static int
#define CLC_FMT_ARGS	(0)
ClockParseformatargsObjCmd(
    ClientData clientData,	/* Client data containing literal pool */
    Tcl_Interp *interp,		/* Tcl interpreter */
    int objc,			/* Parameter count */
    Tcl_Obj *const objv[])	/* Parameter vector */
{
    ClockClientData *dataPtr = clientData;
    Tcl_Obj **litPtr = dataPtr->literals;
    Tcl_Obj *results[3];	/* Format, locale and timezone */
#define formatObj results[0]
#define localeObj results[1]
#define timezoneObj results[2]
#define CLC_SCN_ARGS	(1 << 0)
#define CLC_ADD_ARGS	(1 << 1)

static int
ClockParseFmtScnArgs(
    register
    ClockFmtScnCmdArgs *opts,	/* Result vector: format, locale, timezone... */
    TclDateFields      *date,	/* Extracted date-time corresponding base 
				 * (by scan or add) resp. clockval (by format) */
    int objc,		    /* Parameter count */
    Tcl_Obj *const objv[],	/* Parameter vector */
    int		flags		/* Flags, differentiates between format, scan, add */
) {
    Tcl_Interp	    *interp =  opts->interp;
    ClockClientData *dataPtr = opts->clientData;
    int gmtFlag = 0;
    static const char *const options[] = { /* Command line options expected */
    static const char *const options[] = {
	"-format",	"-gmt",		"-locale",
	"-timezone",	NULL };
	"-timezone",	"-base",	NULL
    };
    enum optionInd {
	CLOCK_FORMAT_FORMAT,	CLOCK_FORMAT_GMT,	CLOCK_FORMAT_LOCALE,
	CLOCK_FORMAT_TIMEZONE
	CLC_ARGS_FORMAT,    CLC_ARGS_GMT,	CLC_ARGS_LOCALE,
	CLC_ARGS_TIMEZONE,  CLC_ARGS_BASE
    };
    int optionIndex;		/* Index of an option. */
    int saw = 0;		/* Flag == 1 if option was seen already. */
    Tcl_WideInt clockVal;	/* Clock value - just used to parse. */
    int i;
    Tcl_WideInt baseVal;	/* Base time, expressed in seconds from the Epoch */

    /*
     * Args consist of a time followed by keyword-value pairs.
    /* clock value (as current base) */
     */

    if ( !(flags & (CLC_SCN_ARGS)) ) {
    if (objc < 2 || (objc % 2) != 0) {
	Tcl_WrongNumArgs(interp, 0, objv,
	opts->baseObj = objv[1];
		"clock format clockval ?-format string? "
		"?-gmt boolean? ?-locale LOCALE? ?-timezone ZONE?");
	Tcl_SetErrorCode(interp, "CLOCK", "wrongNumArgs", NULL);
	return TCL_ERROR;
	saw |= (1 << CLC_ARGS_BASE);
    }

    /*
     * Extract values for the keywords.
     */

    formatObj = litPtr[LIT__DEFAULT_FORMAT];
    localeObj = litPtr[LIT_C];
    timezoneObj = litPtr[LIT__NIL];
    for (i = 2; i < objc; i+=2) {
	/* bypass integers (offsets) by "clock add" */
	if (flags & CLC_ADD_ARGS) {
	    Tcl_WideInt num;
	    if (TclGetWideIntFromObj(NULL, objv[i], &num) == TCL_OK) {
		continue;
	    }
	}
	/* get option */
	if (Tcl_GetIndexFromObj(interp, objv[i], options, "option", 0,
		&optionIndex) != TCL_OK) {
	    Tcl_SetErrorCode(interp, "CLOCK", "badOption",
		    Tcl_GetString(objv[i]), NULL);
	if (Tcl_GetIndexFromObj(interp, objv[i], options, 
	    "option", 0, &optionIndex) != TCL_OK) {
	    goto badOption;
	}
	/* if already specified */
	if (saw & (1 << optionIndex)) {
	    Tcl_SetObjResult(interp, Tcl_ObjPrintf(
		"bad option \"%s\": doubly present", 
		TclGetString(objv[i]))
	    return TCL_ERROR;
	    );
	    goto badOption;
	}
	switch (optionIndex) {
	case CLOCK_FORMAT_FORMAT:
	    formatObj = objv[i+1];
	case CLC_ARGS_FORMAT:
	    if (flags & CLC_ADD_ARGS) {
		goto badOptionMsg;
	    }
	    opts->formatObj = objv[i+1];
	    break;
	case CLOCK_FORMAT_GMT:
	case CLC_ARGS_GMT:
	    if (Tcl_GetBooleanFromObj(interp, objv[i+1], &gmtFlag) != TCL_OK){
		return TCL_ERROR;
	    }
	    break;
	case CLOCK_FORMAT_LOCALE:
	    localeObj = objv[i+1];
	case CLC_ARGS_LOCALE:
	    opts->localeObj = objv[i+1];
	    break;
	case CLOCK_FORMAT_TIMEZONE:
	    timezoneObj = objv[i+1];
	case CLC_ARGS_TIMEZONE:
	    opts->timezoneObj = objv[i+1];
	    break;
	case CLC_ARGS_BASE:
	    if ( !(flags & (CLC_SCN_ARGS)) ) {
		goto badOptionMsg;
	}
	saw |= 1 << optionIndex;
	    }
	    opts->baseObj = objv[i+1];
	    break;
	}
	saw |= (1 << optionIndex);
    }

    /*
     * Check options.
     */

    if (Tcl_GetWideIntFromObj(interp, objv[1], &clockVal) != TCL_OK) {
	return TCL_ERROR;
    }
    if ((saw & (1 << CLOCK_FORMAT_GMT))
	    && (saw & (1 << CLOCK_FORMAT_TIMEZONE))) {
	Tcl_SetObjResult(interp, litPtr[LIT_CANNOT_USE_GMT_AND_TIMEZONE]);
    if ((saw & (1 << CLC_ARGS_GMT))
	    && (saw & (1 << CLC_ARGS_TIMEZONE))) {
	Tcl_SetResult(interp, "cannot use -gmt and -timezone in same call", TCL_STATIC);
	Tcl_SetErrorCode(interp, "CLOCK", "gmtWithTimezone", NULL);
	return TCL_ERROR;
    }
    if (gmtFlag) {
	opts->timezoneObj = dataPtr->literals[LIT_GMT];
    }

    /* If time zone not specified use system time zone */

	timezoneObj = litPtr[LIT_GMT];
    if ( opts->timezoneObj == NULL
      || TclGetString(opts->timezoneObj) == NULL 
      || opts->timezoneObj->length == 0
    ) {
	opts->timezoneObj = ClockGetSystemTimeZone(opts->clientData, interp);
	if (opts->timezoneObj == NULL) {
	    return TCL_ERROR;
	}
    }

    /* Setup timezone (normalize object if needed and load TZ on demand) */

    opts->timezoneObj = ClockSetupTimeZone(opts->clientData, interp, opts->timezoneObj);
    if (opts->timezoneObj == NULL) {
	return TCL_ERROR;
    }

    /* Base (by scan or add) or clock value (by format) */

    if (opts->baseObj != NULL) {
	register Tcl_Obj *baseObj = opts->baseObj;
	/* bypass integer recognition if looks like option "-now" */
	if (
	    (baseObj->length == 4 && baseObj->bytes && *(baseObj->bytes+1) == 'n') ||
	    TclGetWideIntFromObj(NULL, baseObj, &baseVal) != TCL_OK
	) {

	    /* we accept "-now" as current date-time */
	    static const char *const nowOpts[] = {
		"-now", NULL
	    };
	    int idx;
	    if (Tcl_GetIndexFromObj(NULL, baseObj, nowOpts, "seconds or -now",
		    TCL_EXACT, &idx) == TCL_OK
	    ) {
		goto baseNow;
	    }

	    Tcl_SetObjResult(interp, Tcl_ObjPrintf(
		    "expected integer but got \"%s\"",
		    Tcl_GetString(baseObj)));
	    Tcl_SetErrorCode(interp, "TCL", "VALUE", "INTEGER", NULL);
	    i = 1;
	    goto badOption;
	}
	/*
	 * seconds could be an unsigned number that overflowed. Make sure
	 * that it isn't.
	 */

	if (baseObj->typePtr == &tclBignumType) {
	    Tcl_SetObjResult(interp, dataPtr->literals[LIT_INTEGER_VALUE_TOO_LARGE]);
	    return TCL_ERROR;
	}

    } else {

baseNow:
	{
	    Tcl_Time now;
	    Tcl_GetTime(&now);
	    baseVal = (Tcl_WideInt) now.sec;
	}
    }

    /*
     * Extract year, month and day from the base time for the parser to use as
     * defaults
     */

    /* check base fields already cached (by TZ, last-second cache) */
    if ( dataPtr->lastBase.timezoneObj == opts->timezoneObj
      && dataPtr->lastBase.Date.seconds == baseVal) {
	memcpy(date, &dataPtr->lastBase.Date, ClockCacheableDateFieldsSize);
    } else {
	/* extact fields from base */
	date->seconds = baseVal;
	if (ClockGetDateFields(opts->clientData, interp, date, opts->timezoneObj,
	      GREGORIAN_CHANGE_DATE) != TCL_OK) { /* TODO - GREGORIAN_CHANGE_DATE should be locale-dependent */
	    return TCL_ERROR;
	}
	/* cache last base */
	memcpy(&dataPtr->lastBase.Date, date, ClockCacheableDateFieldsSize);
	Tcl_SetObjRef(dataPtr->lastBase.timezoneObj, opts->timezoneObj);
    }

    return TCL_OK;

badOptionMsg: 

    Tcl_SetObjResult(interp, Tcl_ObjPrintf(
	"bad option \"%s\": unexpected for command \"%s\"",
	TclGetString(objv[i]), TclGetString(objv[0]))
    );

badOption:

    Tcl_SetErrorCode(interp, "CLOCK", "badOption",
	    i < objc ? Tcl_GetString(objv[i]) : NULL, NULL);
    
    return TCL_ERROR;
}

/*----------------------------------------------------------------------
 *
 * ClockFormatObjCmd -- , clock format --
 *
 *	This function is invoked to process the Tcl "clock format" command.
 *
 *	Formats a count of seconds since the Posix Epoch as a time of day.
 *
 *	The 'clock format' command formats times of day for output.  Refer 
 *	to the user documentation to see what it does.
 *
 * Results:
 *	Returns a standard Tcl result.
 *
 * Side effects:
 *	None.
 *
 *----------------------------------------------------------------------
 */

int
ClockFormatObjCmd(
    ClientData clientData,	/* Client data containing literal pool */
    Tcl_Interp *interp,		/* Tcl interpreter */
    int objc,			/* Parameter count */
    Tcl_Obj *const objv[])	/* Parameter values */
{
    ClockClientData *dataPtr = clientData;

    int ret;
    ClockFmtScnCmdArgs opts;	/* Format, locale, timezone and base */
    DateFormat	    dateFmt;	/* Common structure used for formatting */

    /* even number of arguments */
    if ((objc & 1) == 1) {
	Tcl_WrongNumArgs(interp, 0, NULL, "clock format clockval|-now "
	    "?-format string? "
	    "?-gmt boolean? "
	    "?-locale LOCALE? ?-timezone ZONE?");
	Tcl_SetErrorCode(interp, "CLOCK", "wrongNumArgs", NULL);
	return TCL_ERROR;
    }

    memset(&dateFmt, 0, sizeof(dateFmt));

    /*
     * Extract values for the keywords.
     */

    ClockInitFmtScnArgs(clientData, interp, &opts);
    ret = ClockParseFmtScnArgs(&opts, &dateFmt.date, objc, objv,
	    CLC_FMT_ARGS);
    if (ret != TCL_OK) {
	goto done;
    }

    /* Default format */
    if (opts.formatObj == NULL) {
	opts.formatObj = dataPtr->literals[LIT__DEFAULT_FORMAT];
    }

    /* Use compiled version of Format - */

    ret = ClockFormat(&dateFmt, &opts);

done:

    Tcl_UnsetObjRef(dateFmt.date.tzName);

    if (ret != TCL_OK) {
	return ret;
    }

    return TCL_OK;
}

/*----------------------------------------------------------------------
 *
 * ClockScanObjCmd -- , clock scan --
 *
 *	This function is invoked to process the Tcl "clock scan" command.
 *
 *	Inputs a count of seconds since the Posix Epoch as a time of day.
 *
 *	The 'clock scan' command scans times of day on input. Refer to the
 *	user documentation to see what it does.
 *
 * Results:
 *	Returns a standard Tcl result.
 *
 * Side effects:
 *	None.
 *
 *----------------------------------------------------------------------
 */

int
ClockScanObjCmd(
    ClientData clientData,	/* Client data containing literal pool */
    Tcl_Interp *interp,		/* Tcl interpreter */
    int objc,			/* Parameter count */
    Tcl_Obj *const objv[])	/* Parameter values */
{
    int ret;
    ClockFmtScnCmdArgs opts;	/* Format, locale, timezone and base */
    DateInfo	    yy;		/* Common structure used for parsing */
    DateInfo	   *info = &yy;

    /* even number of arguments */
    if ((objc & 1) == 1) {
	Tcl_WrongNumArgs(interp, 0, NULL, "clock scan string "
	    "?-base seconds? "
	    "?-format string? "
	    "?-gmt boolean? "
	    "?-locale LOCALE? ?-timezone ZONE?");
	Tcl_SetErrorCode(interp, "CLOCK", "wrongNumArgs", NULL);
	return TCL_ERROR;
    }

    ClockInitDateInfo(&yy);
    
    /*
     * Extract values for the keywords.
     */

    ClockInitFmtScnArgs(clientData, interp, &opts);
    ret = ClockParseFmtScnArgs(&opts, &yy.date, objc, objv,
	    CLC_SCN_ARGS);
    if (ret != TCL_OK) {
	goto done;
    }

    /* seconds are in localSeconds (relative base date), so reset time here */
    yyHour = 0; yyMinutes = 0; yySeconds = 0; yyMeridian = MER24;

    /* If free scan */
    if (opts.formatObj == NULL) {
	/* Use compiled version of FreeScan - */

	/* [SB] TODO: Perhaps someday we'll localize the legacy code. Right now, it's not localized. */
	if (opts.localeObj != NULL) {
	    Tcl_SetResult(interp,
		"legacy [clock scan] does not support -locale", TCL_STATIC);
	    Tcl_SetErrorCode(interp, "CLOCK", "flagWithLegacyFormat", NULL);
	    return TCL_ERROR;
	}
	ret = ClockFreeScan(&yy, objv[1], &opts);
    } 
    else {
	/* Use compiled version of Scan - */

	ret = ClockScan(&yy, objv[1], &opts);
    }

    /* Convert date info structure into UTC seconds */

    if (ret == TCL_OK) {
	ret = ClockScanCommit(clientData, &yy, &opts);
    }

done:

    Tcl_UnsetObjRef(yy.date.tzName);

    if (ret != TCL_OK) {
	return ret;
    }

    Tcl_SetObjResult(interp, Tcl_NewWideIntObj(yy.date.seconds));
    return TCL_OK;
}

/*----------------------------------------------------------------------
 *
 * ClockScanCommit --
 *
 *	Converts date info structure into UTC seconds.
 *
 * Results:
 *	Returns a standard Tcl result.
 *
 * Side effects:
 *	None.
 *
 *----------------------------------------------------------------------
 */

static int
ClockScanCommit(
    ClientData clientData,	/* Client data containing literal pool */
    register DateInfo  *info,	/* Clock scan info structure */
    register
    ClockFmtScnCmdArgs *opts)	/* Format, locale, timezone and base */
{
    /* If needed assemble julianDay using year, month, etc. */
    if (info->flags & CLF_ASSEMBLE_JULIANDAY) {
	if ((info->flags & CLF_ISO8601)) {
	    GetJulianDayFromEraYearWeekDay(&yydate, GREGORIAN_CHANGE_DATE);
	}
	else
	if (!(info->flags & CLF_DAYOFYEAR)) {
	    GetJulianDayFromEraYearMonthDay(&yydate, GREGORIAN_CHANGE_DATE);
	} else {
	    GetJulianDayFromEraYearDay(&yydate, GREGORIAN_CHANGE_DATE);
	}
    }

    /* some overflow checks, if not extended */
    if (!(opts->flags & CLF_EXTENDED)) {
	if (yydate.julianDay > 5373484) {
	    Tcl_SetObjResult(opts->interp, Tcl_NewStringObj(
		"requested date too large to represent", -1));
	    Tcl_SetErrorCode(opts->interp, "CLOCK", "dateTooLarge", NULL);
	    return TCL_ERROR;
	}
    }

    /* Local seconds to UTC (stored in yydate.seconds) */

    if (info->flags & (CLF_ASSEMBLE_SECONDS|CLF_ASSEMBLE_JULIANDAY)) {
	yydate.localSeconds =
	    -210866803200L
	    + ( SECONDS_PER_DAY * (Tcl_WideInt)yydate.julianDay )
	    + ( yySeconds % SECONDS_PER_DAY );
    }

    if (info->flags & (CLF_ASSEMBLE_SECONDS|CLF_ASSEMBLE_JULIANDAY|CLF_LOCALSEC)) {
	if (ConvertLocalToUTC(clientData, opts->interp, &yydate, opts->timezoneObj, 
	      GREGORIAN_CHANGE_DATE) != TCL_OK) {
	    return TCL_ERROR;
	}
    }

    /* Increment UTC seconds with relative time */
    
    yydate.seconds += yyRelSeconds;

    return TCL_OK;
}

/*----------------------------------------------------------------------
 *
 * ClockFreeScan --
 *
 *	Used by ClockScanObjCmd for free scanning without format.
 *
 * Results:
 *	Returns a standard Tcl result.
 *
 * Side effects:
 *	None.
 *
 *----------------------------------------------------------------------
 */

int
ClockFreeScan(
    register
    DateInfo	       *info,	/* Date fields used for parsing & converting
				 * simultaneously a yy-parse structure of the 
				 * TclClockFreeScan */	  
    Tcl_Obj *strObj,		/* String containing the time to scan */
    ClockFmtScnCmdArgs *opts)	/* Command options */
{
    Tcl_Interp	    *interp =  opts->interp;
    ClockClientData *dataPtr = opts->clientData;

    int ret = TCL_ERROR;

    /*
     * Parse the date. The parser will fill a structure "info" with date,
     * time, time zone, relative month/day/seconds, relative weekday, ordinal
     * month.
     * Notice that many yy-defines point to values in the "info" or "date" 
     * structure, e. g. yySeconds -> info->date.secondOfDay or 
     *			yySeconds -> info->date.month (same as yydate.month)
     */
    yyInput = Tcl_GetString(strObj);

    if (TclClockFreeScan(interp, info) != TCL_OK) {
	Tcl_Obj *msg = Tcl_NewObj();
	Tcl_AppendPrintfToObj(msg, "unable to convert date-time string \"%s\": %s", 
	    Tcl_GetString(strObj), TclGetString(Tcl_GetObjResult(interp)));
	Tcl_SetObjResult(interp, msg);
	goto done;
    }

    /*
     * If the caller supplied a date in the string, update the date with
     * the value. If the caller didn't specify a time with the date, default to
     * midnight.
     */

    if (yyHaveDate) {
	if (yyYear < 100) {
	    if (yyYear >= dataPtr->yearOfCenturySwitch) {
		yyYear -= 100;
	    }
	    yyYear += dataPtr->currentYearCentury;
	}
	yydate.era = CE;
	if (yyHaveTime == 0) {
	    yyHaveTime = -1;
	}
	info->flags |= CLF_ASSEMBLE_JULIANDAY|CLF_ASSEMBLE_SECONDS;
    }

    /*
     * If the caller supplied a time zone in the string, make it into a time 
     * zone indicator of +-hhmm and setup this time zone.
     */

    if (yyHaveZone) {
	Tcl_Obj *tzObjStor = NULL;
	int minEast = -yyTimezone;
	int dstFlag = 1 - yyDSTmode;
	tzObjStor = ClockFormatNumericTimeZone(
			  60 * minEast + 3600 * dstFlag);
	Tcl_IncrRefCount(tzObjStor);

	opts->timezoneObj = ClockSetupTimeZone(dataPtr, interp, tzObjStor);

	Tcl_DecrRefCount(tzObjStor);
	if (opts->timezoneObj == NULL) {
	    goto done;
	}

	// Tcl_SetObjRef(yydate.tzName, opts->timezoneObj);

	info->flags |= CLF_ASSEMBLE_SECONDS;
    }
    
    /* 
     * Assemble date, time, zone into seconds-from-epoch
     */

    if (yyHaveTime == -1) {
	yySeconds = 0;
	info->flags |= CLF_ASSEMBLE_SECONDS;
    }
    else
    if (yyHaveTime) {
	yySeconds = ToSeconds(yyHour, yyMinutes,
			    yySeconds, yyMeridian);
	info->flags |= CLF_ASSEMBLE_SECONDS;
    } 
    else 
    if ( (yyHaveDay && !yyHaveDate)
	    || yyHaveOrdinalMonth
	    || ( yyHaveRel
		&& ( yyRelMonth != 0
		     || yyRelDay != 0 ) )
    ) {
	yySeconds = 0;
	info->flags |= CLF_ASSEMBLE_SECONDS;
    } 
    else {
	yySeconds = yydate.localSeconds % SECONDS_PER_DAY;
    }

    /*
     * Do relative times
     */

    ret = ClockCalcRelTime(info, opts);

    /* Free scanning completed - date ready */

done:

    return ret;
}

/*----------------------------------------------------------------------
 *
 * ClockCalcRelTime --
 *
 *	Used for calculating of relative times.
 *
 * Results:
 *	Returns a standard Tcl result.
 *
 * Side effects:
 *	None.
 *
 *----------------------------------------------------------------------
 */
int
ClockCalcRelTime(
    register
    DateInfo	       *info,	/* Date fields used for converting */
    ClockFmtScnCmdArgs *opts)	/* Command options */
{
    /*
     * Because some calculations require in-between conversion of the
     * julian day, we can repeat this processing multiple times 
     */
repeat_rel:

    if (yyHaveRel) {

	/* 
	 * Relative conversion normally possible in UTC time only, because
	 * of possible wrong local time increment if ignores in-between DST-hole.
	 * (see test-cases clock-34.53, clock-34.54).
	 * So increment date in julianDay, but time inside day in UTC (seconds).
	 */

	/* add months (or years in months) */

	if (yyRelMonth != 0) {
	    int m, h;

	    /* if needed extract year, month, etc. again */
	    if (info->flags & CLF_ASSEMBLE_DATE) {
		GetGregorianEraYearDay(&yydate, GREGORIAN_CHANGE_DATE);
		GetMonthDay(&yydate);
		GetYearWeekDay(&yydate, GREGORIAN_CHANGE_DATE);
		info->flags &= ~CLF_ASSEMBLE_DATE;
	    }

	    /* add the requisite number of months */
	    yyMonth += yyRelMonth - 1;
	    yyYear += yyMonth / 12;
	    m = yyMonth % 12;
	    yyMonth = m + 1;

	    /* if the day doesn't exist in the current month, repair it */
	    h = hath[IsGregorianLeapYear(&yydate)][m];
	    if (yyDay > h) {
		yyDay = h;
	    }

	    /* on demand (lazy) assemble julianDay using new year, month, etc. */
	    info->flags |= CLF_ASSEMBLE_JULIANDAY|CLF_ASSEMBLE_SECONDS;

	    yyRelMonth = 0;
	}

	/* add days (or other parts aligned to days) */
	if (yyRelDay) {

	    /* assemble julianDay using new year, month, etc. */
	    if (info->flags & CLF_ASSEMBLE_JULIANDAY) {
		GetJulianDayFromEraYearMonthDay(&yydate, GREGORIAN_CHANGE_DATE);
		info->flags &= ~CLF_ASSEMBLE_JULIANDAY;
	    }
	    yydate.julianDay += yyRelDay;
	    
	    /* julianDay was changed, on demand (lazy) extract year, month, etc. again */
	    info->flags |= CLF_ASSEMBLE_DATE|CLF_ASSEMBLE_SECONDS;

	    yyRelDay = 0;
	}

	/* relative time (seconds), if exceeds current date, do the day conversion and
	 * leave rest of the increment in yyRelSeconds to add it hereafter in UTC seconds */
	if (yyRelSeconds) {
	    int newSecs = yySeconds + yyRelSeconds;
	       
	    /* if seconds increment outside of current date, increment day */
	    if (newSecs / SECONDS_PER_DAY != yySeconds / SECONDS_PER_DAY) {
		
		yyRelDay += newSecs / SECONDS_PER_DAY;
		yySeconds = 0;		    
		yyRelSeconds = newSecs % SECONDS_PER_DAY;

		goto repeat_rel;
	    }
	}

	yyHaveRel = 0;
    }

    /*
     * Do relative (ordinal) month
     */

    if (yyHaveOrdinalMonth) {
	int monthDiff;

	/* if needed extract year, month, etc. again */
	if (info->flags & CLF_ASSEMBLE_DATE) {
	    GetGregorianEraYearDay(&yydate, GREGORIAN_CHANGE_DATE);
	    GetMonthDay(&yydate);
	    GetYearWeekDay(&yydate, GREGORIAN_CHANGE_DATE);
	    info->flags &= ~CLF_ASSEMBLE_DATE;
	}

	if (yyMonthOrdinalIncr > 0) {
	    monthDiff = yyMonthOrdinal - yyMonth;
	    if (monthDiff <= 0) {
		monthDiff += 12;
	    }
	    yyMonthOrdinalIncr--;
	} else {
	    monthDiff = yyMonth - yyMonthOrdinal;
	    if (monthDiff >= 0) {
		monthDiff -= 12;
	    }
	    yyMonthOrdinalIncr++;
	}

	/* process it further via relative times */
	yyHaveRel++;
	yyYear += yyMonthOrdinalIncr;
	yyRelMonth += monthDiff;
	yyHaveOrdinalMonth = 0;

	info->flags |= CLF_ASSEMBLE_JULIANDAY|CLF_ASSEMBLE_SECONDS;

	goto repeat_rel;
    }

    /*
     * Do relative weekday
     */

    if (yyHaveDay && !yyHaveDate) {

	/* if needed assemble julianDay now */
	if (info->flags & CLF_ASSEMBLE_JULIANDAY) {
	    GetJulianDayFromEraYearMonthDay(&yydate, GREGORIAN_CHANGE_DATE);
	    info->flags &= ~CLF_ASSEMBLE_JULIANDAY;
	}

	yydate.era = CE;
	yydate.julianDay = WeekdayOnOrBefore(yyDayNumber, yydate.julianDay + 6)
		    + 7 * yyDayOrdinal;
	if (yyDayOrdinal > 0) {
	    yydate.julianDay -= 7;
	}
	info->flags |= CLF_ASSEMBLE_DATE|CLF_ASSEMBLE_SECONDS;
    }

    return TCL_OK;
}


/*----------------------------------------------------------------------
 *
 * ClockWeekdaysOffs --
 *
 *	Get offset in days for the number of week days corresponding the
 *	given day of week (skipping Saturdays and Sundays).
 *	
 *
 * Results:
 *	Returns a day increment adjusted the given weekdays
 *
 *----------------------------------------------------------------------
 */

static inline int
ClockWeekdaysOffs(
    register int dayOfWeek,
    register int offs)
{
    register int weeks, resDayOfWeek;

    /* offset in days */
    weeks = offs / 5;
    offs = offs % 5;
    /* compiler fix for negative offs - wrap (0, -1) -> (-1, 4) */
    if (offs < 0) {
	weeks--;
	offs = 5 + offs;
    }
    offs += 7 * weeks;

    /* resulting day of week */
    {
	register int day = (offs % 7);
	/* compiler fix for negative offs - wrap (0, -1) -> (-1, 6) */
	if (day < 0) {
	    day = 7 + day;
	}
	resDayOfWeek = dayOfWeek + day;
    }

    /* adjust if we start from a weekend */
    if (dayOfWeek > 5) {
	int adj = 5 - dayOfWeek;
	offs += adj;
	resDayOfWeek += adj;
    }

    /* adjust if we end up on a weekend */
    if (resDayOfWeek > 5) {
       offs += 2;
    }

    return offs;
}



/*----------------------------------------------------------------------
 *
 * ClockAddObjCmd -- , clock add --
 *
 *	Adds an offset to a given time.
 *
 *	Refer to the user documentation to see what it exactly does.
 *
 * Syntax:
 *   clock add clockval ?count unit?... ?-option value?
 *
 * Parameters:
 *   clockval -- Starting time value
 *   count -- Amount of a unit of time to add
 *   unit -- Unit of time to add, must be one of:
 *	     years year months month weeks week
 *	     days day hours hour minutes minute
 *	     seconds second
 *
 * Options:
 *   -gmt BOOLEAN
 *	 Flag synonymous with '-timezone :GMT'
 *   -timezone ZONE
 *	 Name of the time zone in which calculations are to be done.
 *   -locale NAME
 *	 Name of the locale in which calculations are to be done.
 *	 Used to determine the Gregorian change date.
 *
 * Results:
 *	Returns a standard Tcl result with the given time adjusted 
 *	by the given offset(s) in order.
 *
 * Notes:
 *   It is possible that adding a number of months or years will adjust the
 *   day of the month as well.	For instance, the time at one month after
 *   31 January is either 28 or 29 February, because February has fewer
 *   than 31 days.
 *
 *----------------------------------------------------------------------
 */

int
ClockAddObjCmd(
    ClientData clientData,	/* Client data containing literal pool */
    Tcl_Interp *interp,		/* Tcl interpreter */
    int objc,			/* Parameter count */
    Tcl_Obj *const objv[])	/* Parameter values */
{
    ClockClientData *dataPtr = clientData;
    int ret;
    ClockFmtScnCmdArgs opts;	/* Format, locale, timezone and base */
    DateInfo	    yy;		/* Common structure used for parsing */
    DateInfo	   *info = &yy;

    /* add "week" to units also (because otherwise ambiguous) */
    static const char *const units[] = {
	"years",	"months",	    "week",	    "weeks",
	"days",		"weekdays",
	"hours",	"minutes",	    "seconds",
	NULL
    };
    enum unitInd {
	CLC_ADD_YEARS,	CLC_ADD_MONTHS,	    CLC_ADD_WEEK,   CLC_ADD_WEEKS,
	CLC_ADD_DAYS,	CLC_ADD_WEEKDAYS,
	CLC_ADD_HOURS,	CLC_ADD_MINUTES,    CLC_ADD_SECONDS
    };
    int unitIndex;		/* Index of an option. */
    int i;
    Tcl_WideInt offs;

    /* even number of arguments */
    if ((objc & 1) == 1) {
	Tcl_WrongNumArgs(interp, 0, NULL, "clock add clockval|-now ?number units?..."
	    "?-gmt boolean? "
	    "?-locale LOCALE? ?-timezone ZONE?");
	Tcl_SetErrorCode(interp, "CLOCK", "wrongNumArgs", NULL);
	return TCL_ERROR;
    }

    ClockInitDateInfo(&yy);
    
    /*
     * Extract values for the keywords.
     */

    ClockInitFmtScnArgs(clientData, interp, &opts);
    ret = ClockParseFmtScnArgs(&opts, &yy.date, objc, objv,
	    CLC_ADD_ARGS);
    if (ret != TCL_OK) {
	goto done;
    }

    /* time together as seconds of the day */
    yySeconds = yydate.localSeconds % SECONDS_PER_DAY;	 
    /* seconds are in localSeconds (relative base date), so reset time here */
    yyHour = 0; yyMinutes = 0; yyMeridian = MER24;

    ret = TCL_ERROR;

    /*
     * Find each offset and process date increment
     */

    for (i = 2; i < objc; i+=2) {
	/* bypass not integers (options, allready processed above) */
	if (TclGetWideIntFromObj(NULL, objv[i], &offs) != TCL_OK) {
	    continue;
	}
	if (objv[i]->typePtr == &tclBignumType) {
	    Tcl_SetObjResult(interp, dataPtr->literals[LIT_INTEGER_VALUE_TOO_LARGE]);
	    goto done;
	}
	/* get unit */
	if (Tcl_GetIndexFromObj(interp, objv[i+1], units, "unit", 0,
		&unitIndex) != TCL_OK) {
	    goto done;
	}

	/* nothing to do if zero quantity */
	if (!offs) {
	    continue;
	}

	/* if in-between conversion needed (already have relative date/time), 
	 * correct date info, because the date may be changed, 
	 * so refresh it now */

	if ( yyHaveRel
	  && ( unitIndex == CLC_ADD_WEEKDAYS 
	    /* some months can be shorter as another */
	    || yyRelMonth || yyRelDay
	    /* day changed */
	    || yySeconds + yyRelSeconds > SECONDS_PER_DAY
	    || yySeconds + yyRelSeconds < 0
	  )
	) {
	    if (ClockCalcRelTime(info, &opts) != TCL_OK) {
		goto done;
	    }
	}

	/* process increment by offset + unit */
	yyHaveRel++;
	switch (unitIndex) {
	case CLC_ADD_YEARS:
	    yyRelMonth += offs * 12;
	    break;
	case CLC_ADD_MONTHS:
	    yyRelMonth += offs;
	    break;
	case CLC_ADD_WEEK:
	case CLC_ADD_WEEKS:
	    yyRelDay += offs * 7;
	    break;
	case CLC_ADD_DAYS:
	    yyRelDay += offs;
	    break;
	case CLC_ADD_WEEKDAYS:
	    /* add number of week days (skipping Saturdays and Sundays)
	     * to a relative days value. */
	    offs = ClockWeekdaysOffs(yy.date.dayOfWeek, offs);
	    yyRelDay += offs;
	    break;
	case CLC_ADD_HOURS:
	    yyRelSeconds += offs * 60 * 60;
	    break;
	case CLC_ADD_MINUTES:
	    yyRelSeconds += offs * 60;
	    break;
	case CLC_ADD_SECONDS:
	    yyRelSeconds += offs;
	    break;
	}
    }

    /*
     * Return options as a list.
     * Do relative times (if not yet already processed interim):
     */

    if (yyHaveRel) {
	if (ClockCalcRelTime(info, &opts) != TCL_OK) {
	    goto done;
	}
    }
    Tcl_SetObjResult(interp, Tcl_NewListObj(3, results));
    return TCL_OK;

    /* Convert date info structure into UTC seconds */

    ret = ClockScanCommit(clientData, &yy, &opts);

done:
#undef timezoneObj
#undef localeObj
#undef formatObj

    Tcl_UnsetObjRef(yy.date.tzName);

    if (ret != TCL_OK) {
	return ret;
    }

    Tcl_SetObjResult(interp, Tcl_NewWideIntObj(yy.date.seconds));
    return TCL_OK;
}

/*----------------------------------------------------------------------
 *
 * ClockSecondsObjCmd -
 *
 *	Returns a count of microseconds since the epoch.

    Tcl_Interp *interp,		/* Tcl interpreter */
    int objc,			/* Parameter count */
    Tcl_Obj *const *objv)	/* Parameter values */
{
    Tcl_Time now;

    if (objc != 1) {
	Tcl_WrongNumArgs(interp, 1, objv, NULL);
	Tcl_WrongNumArgs(interp, 0, NULL, "clock seconds");
	return TCL_ERROR;
    }
    Tcl_GetTime(&now);
    Tcl_SetObjResult(interp, Tcl_NewWideIntObj((Tcl_WideInt) now.sec));
    return TCL_OK;
}

/*
 *----------------------------------------------------------------------
 *
 * TzsetIfNecessary --
 * TzsetGetEpoch --, TzsetIfNecessary --
 *
 *	Calls the tzset() library function if the contents of the TZ
 *	environment variable has changed.
 *
 * Results:
 *	None.
 *
 * Side effects:
 *	Calls tzset.
 *
 *----------------------------------------------------------------------
 */

static void
TzsetIfNecessary(void)
static unsigned long
TzsetGetEpoch(void)
{
    static char* tzWas = INT2PTR(-1);	/* Previous value of TZ, protected by
				 * clockMutex. */
    const char *tzIsNow;	/* Current value of TZ */

    static char* tzWas = INT2PTR(-1);	 /* Previous value of TZ, protected by
					  * clockMutex. */
    static long	 tzLastRefresh = 0;	 /* Used for latency before next refresh */
    static unsigned long tzWasEpoch = 0; /* Epoch, signals that TZ changed */
    static unsigned long tzEnvEpoch = 0; /* Last env epoch, for faster signaling, 
					    that TZ changed via TCL */
    
    const char *tzIsNow;		 /* Current value of TZ */
    
    /* 
     * Prevent performance regression on some platforms by resolving of system time zone:
     * small latency for check whether environment was changed (once per second)
     * no latency if environment was chaned with tcl-env (compare both epoch values)
     */
    Tcl_Time now;
    Tcl_GetTime(&now);
    if (now.sec == tzLastRefresh && tzEnvEpoch == TclEnvEpoch) {
	return tzWasEpoch;
    }
    tzEnvEpoch = TclEnvEpoch;
    tzLastRefresh = now.sec;

    /* check in lock */
    Tcl_MutexLock(&clockMutex);
    tzIsNow = getenv("TCL_TZ");
    if (tzIsNow == NULL) {
    tzIsNow = getenv("TZ");
	tzIsNow = getenv("TZ");
    }
    if (tzIsNow != NULL && (tzWas == NULL || tzWas == INT2PTR(-1)
	    || strcmp(tzIsNow, tzWas) != 0)) {
	tzset();
	if (tzWas != NULL && tzWas != INT2PTR(-1)) {
	    ckfree(tzWas);
	}
	tzWas = ckalloc(strlen(tzIsNow) + 1);
	strcpy(tzWas, tzIsNow);
	tzWasEpoch++;
    } else if (tzIsNow == NULL && tzWas != NULL) {
	tzset();
	if (tzWas != INT2PTR(-1)) ckfree(tzWas);
	tzWas = NULL;
	tzWasEpoch++;
    }
    Tcl_MutexUnlock(&clockMutex);
}


    return tzWasEpoch;
}
/*
 *----------------------------------------------------------------------
 *

 * ClockDeleteCmdProc --
 *
 *	Remove a reference to the clock client data, and clean up memory
 *	when it's all gone.
 *
 * Results:
 *	None.
 *
 *----------------------------------------------------------------------
 */

static void
ClockDeleteCmdProc(
TzsetIfNecessary(void)
    ClientData clientData)	/* Opaque pointer to the client data */
{
    ClockClientData *data = clientData;
    int i;

    TzsetGetEpoch();
    if (data->refCount-- <= 1) {
	for (i = 0; i < LIT__END; ++i) {
	    Tcl_DecrRefCount(data->literals[i]);
	}
	ckfree(data->literals);
	ckfree(data);
    }
}

/*
 * Local Variables:
 * mode: c
 * c-basic-offset: 4
 * fill-column: 78
 * End:
 */