Merge commit '29ccecd87709feda60d191f6aaba324ccad91f55' as 'tcl8.6'

1 files changed, 2090 insertions, 0 deletions

diff --git a/tcl8.6/generic/tclClock.c b/tcl8.6/generic/tclClock.c
new file mode 100644
index 0000000..bbfc83b
--- /dev/null
+++ b/tcl8.6/generic/tclClock.c
@@ -0,0 +1,2090 @@
+/*
+ * 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.
+ *
+ * See the file "license.terms" for information on usage and redistribution of
+ * this file, and for a DISCLAIMER OF ALL WARRANTIES.
+ */
+
+#include "tclInt.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;
+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]
+ */
+
+typedef struct {
+    size_t refCount;		/* Number of live references. */
+    Tcl_Obj **literals;		/* Pool of object literals. */
+} ClockClientData;
+
+/*
+ * Structure containing the fields used in [clock format] and [clock scan]
+ */
+
+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[]);
+static int		ConvertUTCToLocalUsingC(Tcl_Interp *,
+			    TclDateFields *, int);
+static int		ConvertLocalToUTC(Tcl_Interp *,
+			    TclDateFields *, Tcl_Obj *, int);
+static int		ConvertLocalToUTCUsingTable(Tcl_Interp *,
+			    TclDateFields *, int, Tcl_Obj *const[]);
+static int		ConvertLocalToUTCUsingC(Tcl_Interp *,
+			    TclDateFields *, int);
+static Tcl_Obj *	LookupLastTransition(Tcl_Interp *, Tcl_WideInt,
+			    int, Tcl_Obj *const *);
+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		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		ClockParseformatargsObjCmd(
+			    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 struct tm *	ThreadSafeLocalTime(const time_t *);
+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
+				 * will always have the ClockClientData sent
+				 * to it, but may well ignore this data. */
+};
+
+static const struct ClockCommand clockCommands[] = {
+    { "getenv",			ClockGetenvObjCmd },
+    { "Oldscan",		TclClockOldscanObjCmd },
+    { "ConvertLocalToUTC",	ClockConvertlocaltoutcObjCmd },
+    { "GetDateFields",		ClockGetdatefieldsObjCmd },
+    { "GetJulianDayFromEraYearMonthDay",
+		ClockGetjuliandayfromerayearmonthdayObjCmd },
+    { "GetJulianDayFromEraYearWeekDay",
+		ClockGetjuliandayfromerayearweekdayObjCmd },
+    { "ParseFormatArgs",	ClockParseformatargsObjCmd },
+    { NULL, NULL }
+};
+
+/*
+ *----------------------------------------------------------------------
+ *
+ * TclClockInit --
+ *
+ *	Registers the 'clock' subcommands with the Tcl interpreter and
+ *	initializes its client data (which consists mostly of constant
+ *	Tcl_Obj's that it is too much trouble to keep recreating).
+ *
+ * Results:
+ *	None.
+ *
+ * Side effects:
+ *	Installs the commands and creates the client data
+ *
+ *----------------------------------------------------------------------
+ */
+
+void
+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. */
+    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]);
+    }
+
+    /*
+     * 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++) {
+	strcpy(cmdName + TCL_CLOCK_PREFIX_LEN, clockCmdPtr->name);
+	data->refCount++;
+	Tcl_CreateObjCommand(interp, cmdName, clockCmdPtr->objCmdProc, data,
+		ClockDeleteCmdProc);
+    }
+
+    /* Make the clock ensemble */
+
+    TclMakeEnsemble(interp, "clock", clockImplMap);
+}
+
+/*
+ *----------------------------------------------------------------------
+ *
+ * ClockConvertlocaltoutcObjCmd --
+ *
+ *	Tcl command that converts a UTC time to a local time by whatever means
+ *	is available.
+ *
+ * Usage:
+ *	::tcl::clock::ConvertUTCToLocal dictionary tzdata changeover
+ *
+ * Parameters:
+ *	dict - Dictionary containing a 'localSeconds' entry.
+ *	tzdata - Time zone data
+ *	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
+ *	augmented with a 'seconds' field giving the UTC time. On failure,
+ *	leaves an error message in the interpreter result.
+ *
+ *----------------------------------------------------------------------
+ */
+
+static int
+ClockConvertlocaltoutcObjCmd(
+    ClientData clientData,	/* Client data */
+    Tcl_Interp *interp,		/* Tcl interpreter */
+    int objc,			/* Parameter count */
+    Tcl_Obj *const *objv)	/* Parameter vector */
+{
+    ClockClientData *data = clientData;
+    Tcl_Obj *const *literals = data->literals;
+    Tcl_Obj *secondsObj;
+    Tcl_Obj *dict;
+    int changeover;
+    TclDateFields fields;
+    int created = 0;
+    int status;
+
+    /*
+     * Check params and convert time.
+     */
+
+    if (objc != 4) {
+	Tcl_WrongNumArgs(interp, 1, objv, "dict tzdata 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 ((TclGetWideIntFromObj(interp, secondsObj,
+	    &fields.localSeconds) != TCL_OK)
+	|| (TclGetIntFromObj(interp, objv[3], &changeover) != TCL_OK)
+	|| ConvertLocalToUTC(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.
+     */
+
+    if (Tcl_IsShared(dict)) {
+	dict = Tcl_DuplicateObj(dict);
+	created = 1;
+	Tcl_IncrRefCount(dict);
+    }
+    status = Tcl_DictObjPut(interp, dict, literals[LIT_SECONDS],
+	    Tcl_NewWideIntObj(fields.seconds));
+    if (status == TCL_OK) {
+	Tcl_SetObjResult(interp, dict);
+    }
+    if (created) {
+	Tcl_DecrRefCount(dict);
+    }
+    return status;
+}
+
+/*
+ *----------------------------------------------------------------------
+ *
+ * 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
+ *
+ * Parameters:
+ *	seconds - Time expressed in seconds from the Posix epoch.
+ *	tzdata - Time zone data of the time zone in which time is to be
+ *		 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
+ *			       local time zone.
+ *		tzOffset - Time zone offset in seconds east of Greenwich
+ *		tzName - Time zone name
+ *		julianDay - Julian Day Number in the local time zone
+ *
+ *----------------------------------------------------------------------
+ */
+
+int
+ClockGetdatefieldsObjCmd(
+    ClientData clientData,	/* Opaque pointer to literal pool, etc. */
+    Tcl_Interp *interp,		/* Tcl interpreter */
+    int objc,			/* Parameter count */
+    Tcl_Obj *const *objv)	/* Parameter vector */
+{
+    TclDateFields fields;
+    Tcl_Obj *dict;
+    ClockClientData *data = clientData;
+    Tcl_Obj *const *literals = data->literals;
+    int changeover;
+
+    /*
+     * Check params.
+     */
+
+    if (objc != 4) {
+	Tcl_WrongNumArgs(interp, 1, objv, "seconds tzdata changeover");
+	return TCL_ERROR;
+    }
+    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;
+    }
+
+    /*
+     * Convert UTC time to local.
+     */
+
+    if (ConvertUTCToLocal(interp, &fields, objv[2], 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);
+
+    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_DecrRefCount(fields.tzName);
+    Tcl_DictObjPut(NULL, dict, literals[LIT_TZOFFSET],
+	    Tcl_NewIntObj(fields.tzOffset));
+    Tcl_DictObjPut(NULL, dict, literals[LIT_JULIANDAY],
+	    Tcl_NewIntObj(fields.julianDay));
+    Tcl_DictObjPut(NULL, dict, literals[LIT_GREGORIAN],
+	    Tcl_NewIntObj(fields.gregorian));
+    Tcl_DictObjPut(NULL, dict, literals[LIT_ERA],
+	    literals[fields.era ? LIT_BCE : LIT_CE]);
+    Tcl_DictObjPut(NULL, dict, literals[LIT_YEAR],
+	    Tcl_NewIntObj(fields.year));
+    Tcl_DictObjPut(NULL, dict, literals[LIT_DAYOFYEAR],
+	    Tcl_NewIntObj(fields.dayOfYear));
+    Tcl_DictObjPut(NULL, dict, literals[LIT_MONTH],
+	    Tcl_NewIntObj(fields.month));
+    Tcl_DictObjPut(NULL, dict, literals[LIT_DAYOFMONTH],
+	    Tcl_NewIntObj(fields.dayOfMonth));
+    Tcl_DictObjPut(NULL, dict, literals[LIT_ISO8601YEAR],
+	    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;
+}
+
+/*
+ *----------------------------------------------------------------------
+ *
+ * ClockGetjuliandayfromerayearmonthdayObjCmd --
+ *
+ *	Tcl command that converts a time from era-year-month-day to a Julian
+ *	Day Number.
+ *
+ * Parameters:
+ *	dict - Dictionary that contains 'era', 'year', 'month' and
+ *	       'dayOfMonth' keys.
+ *	changeover - Julian Day of changeover to the Gregorian calendar
+ *
+ * Results:
+ *	Result is either TCL_OK, with the interpreter result being the
+ *	dictionary augmented with a 'julianDay' key, or TCL_ERROR,
+ *	with the result being an error message.
+ *
+ *----------------------------------------------------------------------
+ */
+
+static int
+FetchEraField(
+    Tcl_Interp *interp,
+    Tcl_Obj *dict,
+    Tcl_Obj *key,
+    int *storePtr)
+{
+    Tcl_Obj *value = NULL;
+
+    if (Tcl_DictObjGet(interp, dict, key, &value) != TCL_OK) {
+	return TCL_ERROR;
+    }
+    if (value == NULL) {
+	Tcl_SetObjResult(interp, Tcl_NewStringObj(
+		"expected key(s) not found in dictionary", -1));
+	return TCL_ERROR;
+    }
+    return Tcl_GetIndexFromObj(interp, value, eras, "era", TCL_EXACT, storePtr);
+}
+
+static int
+FetchIntField(
+    Tcl_Interp *interp,
+    Tcl_Obj *dict,
+    Tcl_Obj *key,
+    int *storePtr)
+{
+    Tcl_Obj *value = NULL;
+
+    if (Tcl_DictObjGet(interp, dict, key, &value) != TCL_OK) {
+	return TCL_ERROR;
+    }
+    if (value == NULL) {
+	Tcl_SetObjResult(interp, Tcl_NewStringObj(
+		"expected key(s) not found in dictionary", -1));
+	return TCL_ERROR;
+    }
+    return TclGetIntFromObj(interp, value, storePtr);
+}
+
+static int
+ClockGetjuliandayfromerayearmonthdayObjCmd(
+    ClientData clientData,	/* Opaque pointer to literal pool, etc. */
+    Tcl_Interp *interp,		/* Tcl interpreter */
+    int objc,			/* Parameter count */
+    Tcl_Obj *const *objv)	/* Parameter vector */
+{
+    TclDateFields fields;
+    Tcl_Obj *dict;
+    ClockClientData *data = clientData;
+    Tcl_Obj *const *literals = data->literals;
+    int changeover;
+    int copied = 0;
+    int status;
+    int era = 0;
+
+    /*
+     * Check params.
+     */
+
+    if (objc != 3) {
+	Tcl_WrongNumArgs(interp, 1, objv, "dict changeover");
+	return TCL_ERROR;
+    }
+    dict = objv[1];
+    if (FetchEraField(interp, dict, literals[LIT_ERA], &era) != TCL_OK
+	    || FetchIntField(interp, dict, literals[LIT_YEAR], &fields.year)
+		!= TCL_OK
+	    || FetchIntField(interp, dict, literals[LIT_MONTH], &fields.month)
+		!= TCL_OK
+	    || FetchIntField(interp, dict, literals[LIT_DAYOFMONTH],
+		&fields.dayOfMonth) != TCL_OK
+	    || TclGetIntFromObj(interp, objv[2], &changeover) != TCL_OK) {
+	return TCL_ERROR;
+    }
+    fields.era = era;
+
+    /*
+     * Get Julian day.
+     */
+
+    GetJulianDayFromEraYearMonthDay(&fields, changeover);
+
+    /*
+     * Store Julian day in the dictionary - copy on write.
+     */
+
+    if (Tcl_IsShared(dict)) {
+	dict = Tcl_DuplicateObj(dict);
+	Tcl_IncrRefCount(dict);
+	copied = 1;
+    }
+    status = Tcl_DictObjPut(interp, dict, literals[LIT_JULIANDAY],
+	    Tcl_NewIntObj(fields.julianDay));
+    if (status == TCL_OK) {
+	Tcl_SetObjResult(interp, dict);
+    }
+    if (copied) {
+	Tcl_DecrRefCount(dict);
+    }
+    return status;
+}
+
+/*
+ *----------------------------------------------------------------------
+ *
+ * ClockGetjuliandayfromerayearweekdayObjCmd --
+ *
+ *	Tcl command that converts a time from the ISO calendar to a Julian Day
+ *	Number.
+ *
+ * Parameters:
+ *	dict - Dictionary that contains 'era', 'iso8601Year', 'iso8601Week'
+ *	       and 'dayOfWeek' keys.
+ *	changeover - Julian Day of changeover to the Gregorian calendar
+ *
+ * Results:
+ *	Result is either TCL_OK, with the interpreter result being the
+ *	dictionary augmented with a 'julianDay' key, or TCL_ERROR, with the
+ *	result being an error message.
+ *
+ *----------------------------------------------------------------------
+ */
+
+static int
+ClockGetjuliandayfromerayearweekdayObjCmd(
+    ClientData clientData,	/* Opaque pointer to literal pool, etc. */
+    Tcl_Interp *interp,		/* Tcl interpreter */
+    int objc,			/* Parameter count */
+    Tcl_Obj *const *objv)	/* Parameter vector */
+{
+    TclDateFields fields;
+    Tcl_Obj *dict;
+    ClockClientData *data = clientData;
+    Tcl_Obj *const *literals = data->literals;
+    int changeover;
+    int copied = 0;
+    int status;
+    int era = 0;
+
+    /*
+     * Check params.
+     */
+
+    if (objc != 3) {
+	Tcl_WrongNumArgs(interp, 1, objv, "dict changeover");
+	return TCL_ERROR;
+    }
+    dict = objv[1];
+    if (FetchEraField(interp, dict, literals[LIT_ERA], &era) != TCL_OK
+	    || FetchIntField(interp, dict, literals[LIT_ISO8601YEAR],
+		&fields.iso8601Year) != TCL_OK
+	    || FetchIntField(interp, dict, literals[LIT_ISO8601WEEK],
+		&fields.iso8601Week) != TCL_OK
+	    || FetchIntField(interp, dict, literals[LIT_DAYOFWEEK],
+		&fields.dayOfWeek) != TCL_OK
+	    || TclGetIntFromObj(interp, objv[2], &changeover) != TCL_OK) {
+	return TCL_ERROR;
+    }
+    fields.era = era;
+
+    /*
+     * Get Julian day.
+     */
+
+    GetJulianDayFromEraYearWeekDay(&fields, changeover);
+
+    /*
+     * Store Julian day in the dictionary - copy on write.
+     */
+
+    if (Tcl_IsShared(dict)) {
+	dict = Tcl_DuplicateObj(dict);
+	Tcl_IncrRefCount(dict);
+	copied = 1;
+    }
+    status = Tcl_DictObjPut(interp, dict, literals[LIT_JULIANDAY],
+	    Tcl_NewIntObj(fields.julianDay));
+    if (status == TCL_OK) {
+	Tcl_SetObjResult(interp, dict);
+    }
+    if (copied) {
+	Tcl_DecrRefCount(dict);
+    }
+    return status;
+}
+
+/*
+ *----------------------------------------------------------------------
+ *
+ * ConvertLocalToUTC --
+ *
+ *	Converts a time (in a TclDateFields structure) from the local wall
+ *	clock to UTC.
+ *
+ * Results:
+ *	Returns a standard Tcl result.
+ *
+ * Side effects:
+ *	Populates the 'seconds' field if successful; stores an error message
+ *	in the interpreter result on failure.
+ *
+ *----------------------------------------------------------------------
+ */
+
+static int
+ConvertLocalToUTC(
+    Tcl_Interp *interp,		/* Tcl interpreter */
+    TclDateFields *fields,	/* Fields of the time */
+    Tcl_Obj *tzdata,		/* Time zone data */
+    int changeover)		/* Julian Day of the Gregorian transition */
+{
+    int rowc;			/* Number of rows in tzdata */
+    Tcl_Obj **rowv;		/* Pointers to the rows */
+
+    /*
+     * Unpack the tz data.
+     */
+
+    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) {
+	return ConvertLocalToUTCUsingC(interp, fields, changeover);
+    } else {
+	return ConvertLocalToUTCUsingTable(interp, fields, rowc, rowv);
+    }
+}
+
+/*
+ *----------------------------------------------------------------------
+ *
+ * ConvertLocalToUTCUsingTable --
+ *
+ *	Converts a time (in a TclDateFields structure) from local time in a
+ *	given time zone to UTC.
+ *
+ * Results:
+ *	Returns a standard Tcl result.
+ *
+ * Side effects:
+ *	Stores an error message in the interpreter if an error occurs; if
+ *	successful, stores the 'seconds' field in 'fields.
+ *
+ *----------------------------------------------------------------------
+ */
+
+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 *row;
+    int cellc;
+    Tcl_Obj **cellv;
+    int have[8];
+    int nHave = 0;
+    int i;
+    int found;
+
+    /*
+     * Perform an initial lookup assuming that local == UTC, and locate the
+     * last time conversion prior to that time. Get the offset from that row,
+     * and look up again. Continue until we find an offset that we found
+     * before. This definition, rather than "the same offset" ensures that we
+     * don't enter an endless loop, as would otherwise happen when trying to
+     * convert a non-existent time such as 02:30 during the US Spring Daylight
+     * Saving Time transition.
+     */
+
+    found = 0;
+    fields->tzOffset = 0;
+    fields->seconds = fields->localSeconds;
+    while (!found) {
+	row = LookupLastTransition(interp, fields->seconds, rowc, rowv);
+	if ((row == NULL)
+		|| TclListObjGetElements(interp, row, &cellc,
+		    &cellv) != TCL_OK
+		|| TclGetIntFromObj(interp, cellv[1],
+		    &fields->tzOffset) != TCL_OK) {
+	    return TCL_ERROR;
+	}
+	found = 0;
+	for (i = 0; !found && i < nHave; ++i) {
+	    if (have[i] == fields->tzOffset) {
+		found = 1;
+		break;
+	    }
+	}
+	if (!found) {
+	    if (nHave == 8) {
+		Tcl_Panic("loop in ConvertLocalToUTCUsingTable");
+	    }
+	    have[nHave++] = fields->tzOffset;
+	}
+	fields->seconds = fields->localSeconds - fields->tzOffset;
+    }
+    fields->tzOffset = have[i];
+    fields->seconds = fields->localSeconds - fields->tzOffset;
+    return TCL_OK;
+}
+
+/*
+ *----------------------------------------------------------------------
+ *
+ * ConvertLocalToUTCUsingC --
+ *
+ *	Converts a time from local wall clock to UTC when the local time zone
+ *	cannot be determined. Uses 'mktime' to do the job.
+ *
+ * Results:
+ *	Returns a standard Tcl result.
+ *
+ * Side effects:
+ *	Stores an error message in the interpreter if an error occurs; if
+ *	successful, stores the 'seconds' field in 'fields.
+ *
+ *----------------------------------------------------------------------
+ */
+
+static int
+ConvertLocalToUTCUsingC(
+    Tcl_Interp *interp,		/* Tcl interpreter */
+    TclDateFields *fields,	/* Time to convert, with 'seconds' filled in */
+    int changeover)		/* Julian Day of the Gregorian transition */
+{
+    struct tm timeVal;
+    int localErrno;
+    int secondOfDay;
+    Tcl_WideInt jsec;
+
+    /*
+     * Convert the given time to a date.
+     */
+
+    jsec = fields->localSeconds + JULIAN_SEC_POSIX_EPOCH;
+    fields->julianDay = (int) (jsec / SECONDS_PER_DAY);
+    secondOfDay = (int)(jsec % SECONDS_PER_DAY);
+    if (secondOfDay < 0) {
+	secondOfDay += SECONDS_PER_DAY;
+	fields->julianDay--;
+    }
+    GetGregorianEraYearDay(fields, changeover);
+    GetMonthDay(fields);
+
+    /*
+     * Convert the date/time to a 'struct tm'.
+     */
+
+    timeVal.tm_year = fields->year - 1900;
+    timeVal.tm_mon = fields->month - 1;
+    timeVal.tm_mday = fields->dayOfMonth;
+    timeVal.tm_hour = (secondOfDay / 3600) % 24;
+    timeVal.tm_min = (secondOfDay / 60) % 60;
+    timeVal.tm_sec = secondOfDay % 60;
+    timeVal.tm_isdst = -1;
+    timeVal.tm_wday = -1;
+    timeVal.tm_yday = -1;
+
+    /*
+     * Get local time. It is rumored that mktime is not thread safe on some
+     * platforms, so seize a mutex before attempting this.
+     */
+
+    TzsetIfNecessary();
+    Tcl_MutexLock(&clockMutex);
+    errno = 0;
+    fields->seconds = (Tcl_WideInt) mktime(&timeVal);
+    localErrno = errno;
+    Tcl_MutexUnlock(&clockMutex);
+
+    /*
+     * If conversion fails, report an error.
+     */
+
+    if (localErrno != 0
+	    || (fields->seconds == -1 && timeVal.tm_yday == -1)) {
+	Tcl_SetObjResult(interp, Tcl_NewStringObj(
+		"time value too large/small to represent", -1));
+	return TCL_ERROR;
+    }
+    return TCL_OK;
+}
+
+/*
+ *----------------------------------------------------------------------
+ *
+ * ConvertUTCToLocal --
+ *
+ *	Converts a time (in a TclDateFields structure) from UTC to local time.
+ *
+ * Results:
+ *	Returns a standard Tcl result.
+ *
+ * Side effects:
+ *	Populates the 'tzName' and 'tzOffset' fields.
+ *
+ *----------------------------------------------------------------------
+ */
+
+static int
+ConvertUTCToLocal(
+    Tcl_Interp *interp,		/* Tcl interpreter */
+    TclDateFields *fields,	/* Fields of the time */
+    Tcl_Obj *tzdata,		/* Time zone data */
+    int changeover)		/* Julian Day of the Gregorian transition */
+{
+    int rowc;			/* Number of rows in tzdata */
+    Tcl_Obj **rowv;		/* Pointers to the rows */
+
+    /*
+     * Unpack the tz data.
+     */
+
+    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) {
+	return ConvertUTCToLocalUsingC(interp, fields, changeover);
+    } else {
+	return ConvertUTCToLocalUsingTable(interp, fields, rowc, rowv);
+    }
+}
+
+/*
+ *----------------------------------------------------------------------
+ *
+ * ConvertUTCToLocalUsingTable --
+ *
+ *	Converts UTC to local time, given a table of transition points
+ *
+ * Results:
+ *	Returns a standard Tcl result
+ *
+ * Side effects:
+ *	On success, fills fields->tzName, fields->tzOffset and
+ *	fields->localSeconds. On failure, places an error message in the
+ *	interpreter result.
+ *
+ *----------------------------------------------------------------------
+ */
+
+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 *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);
+    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_IncrRefCount(fields->tzName);
+    fields->localSeconds = fields->seconds + fields->tzOffset;
+    return TCL_OK;
+}
+
+/*
+ *----------------------------------------------------------------------
+ *
+ * ConvertUTCToLocalUsingC --
+ *
+ *	Converts UTC to localtime in cases where the local time zone is not
+ *	determinable, using the C 'localtime' function to do it.
+ *
+ * Results:
+ *	Returns a standard Tcl result.
+ *
+ * Side effects:
+ *	On success, fills fields->tzName, fields->tzOffset and
+ *	fields->localSeconds. On failure, places an error message in the
+ *	interpreter result.
+ *
+ *----------------------------------------------------------------------
+ */
+
+static int
+ConvertUTCToLocalUsingC(
+    Tcl_Interp *interp,		/* Tcl interpreter */
+    TclDateFields *fields,	/* Time to convert, with 'seconds' filled in */
+    int changeover)		/* Julian Day of the Gregorian transition */
+{
+    time_t tock;
+    struct tm *timeVal;		/* Time after conversion */
+    int diff;			/* Time zone diff local-Greenwich */
+    char buffer[8];		/* Buffer for time zone name */
+
+    /*
+     * Use 'localtime' to determine local year, month, day, time of day.
+     */
+
+    tock = (time_t) fields->seconds;
+    if ((Tcl_WideInt) tock != fields->seconds) {
+	Tcl_SetObjResult(interp, Tcl_NewStringObj(
+		"number too large to represent as a Posix time", -1));
+	Tcl_SetErrorCode(interp, "CLOCK", "argTooLarge", NULL);
+	return TCL_ERROR;
+    }
+    TzsetIfNecessary();
+    timeVal = ThreadSafeLocalTime(&tock);
+    if (timeVal == NULL) {
+	Tcl_SetObjResult(interp, Tcl_NewStringObj(
+		"localtime failed (clock value may be too "
+		"large/small to represent)", -1));
+	Tcl_SetErrorCode(interp, "CLOCK", "localtimeFailed", NULL);
+	return TCL_ERROR;
+    }
+
+    /*
+     * Fill in the date in 'fields' and use it to derive Julian Day.
+     */
+
+    fields->era = CE;
+    fields->year = timeVal->tm_year + 1900;
+    fields->month = timeVal->tm_mon + 1;
+    fields->dayOfMonth = timeVal->tm_mday;
+    GetJulianDayFromEraYearMonthDay(fields, changeover);
+
+    /*
+     * Convert that value to seconds.
+     */
+
+    fields->localSeconds = (((fields->julianDay * (Tcl_WideInt) 24
+	    + timeVal->tm_hour) * 60 + timeVal->tm_min) * 60
+	    + timeVal->tm_sec) - JULIAN_SEC_POSIX_EPOCH;
+
+    /*
+     * Determine a time zone offset and name; just use +hhmm for the name.
+     */
+
+    diff = (int) (fields->localSeconds - fields->seconds);
+    fields->tzOffset = diff;
+    if (diff < 0) {
+	*buffer = '-';
+	diff = -diff;
+    } else {
+	*buffer = '+';
+    }
+    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_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 *
+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 */
+{
+    int l;
+    int u;
+    Tcl_Obj *compObj;
+    Tcl_WideInt compVal;
+
+    /*
+     * Examine the first row to make sure we're in bounds.
+     */
+
+    if (Tcl_ListObjIndex(interp, rowv[0], 0, &compObj) != 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];
+    }
+
+    /*
+     * 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 ||
+		TclGetWideIntFromObj(interp, compObj, &compVal) != TCL_OK) {
+	    return NULL;
+	}
+	if (tick >= compVal) {
+	    l = m;
+	} else {
+	    u = m-1;
+	}
+    }
+    return rowv[l];
+}
+
+/*
+ *----------------------------------------------------------------------
+ *
+ * GetYearWeekDay --
+ *
+ *	Given a date with Julian Calendar Day, compute the year, week, and day
+ *	in the ISO8601 calendar.
+ *
+ * Results:
+ *	None.
+ *
+ * Side effects:
+ *	Stores 'iso8601Year', 'iso8601Week' and 'dayOfWeek' in the date
+ *	fields.
+ *
+ *----------------------------------------------------------------------
+ */
+
+static void
+GetYearWeekDay(
+    TclDateFields *fields,	/* Date to convert, must have 'julianDay' */
+    int changeover)		/* Julian Day Number of the Gregorian
+				 * transition */
+{
+    TclDateFields temp;
+    int dayOfFiscalYear;
+
+    /*
+     * 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;
+    GetGregorianEraYearDay(&temp, changeover);
+    if (temp.era == BCE) {
+	temp.iso8601Year = temp.year - 1;
+    } else {
+	temp.iso8601Year = temp.year + 1;
+    }
+    temp.iso8601Week = 1;
+    temp.dayOfWeek = 1;
+    GetJulianDayFromEraYearWeekDay(&temp, changeover);
+
+    /*
+     * temp.julianDay is now the start of an ISO8601 year, either the one
+     * corresponding to the given date, or the one after. If we guessed high,
+     * move one year earlier
+     */
+
+    if (fields->julianDay < temp.julianDay) {
+	if (temp.era == BCE) {
+	    temp.iso8601Year += 1;
+	} else {
+	    temp.iso8601Year -= 1;
+	}
+	GetJulianDayFromEraYearWeekDay(&temp, changeover);
+    }
+
+    fields->iso8601Year = temp.iso8601Year;
+    dayOfFiscalYear = fields->julianDay - temp.julianDay;
+    fields->iso8601Week = (dayOfFiscalYear / 7) + 1;
+    fields->dayOfWeek = (dayOfFiscalYear + 1) % 7;
+    if (fields->dayOfWeek < 1) {
+	fields->dayOfWeek += 7;
+    }
+}
+
+/*
+ *----------------------------------------------------------------------
+ *
+ * GetGregorianEraYearDay --
+ *
+ *	Given a Julian Day Number, extracts the year and day of the year and
+ *	puts them into TclDateFields, along with the era (BCE or CE) and a
+ *	flag indicating whether the date is Gregorian or Julian.
+ *
+ * Results:
+ *	None.
+ *
+ * Side effects:
+ *	Stores 'era', 'gregorian', 'year', and 'dayOfYear'.
+ *
+ *----------------------------------------------------------------------
+ */
+
+static void
+GetGregorianEraYearDay(
+    TclDateFields *fields,	/* Date fields containing 'julianDay' */
+    int changeover)		/* Gregorian transition date */
+{
+    int jday = fields->julianDay;
+    int day;
+    int year;
+    int n;
+
+    if (jday >= changeover) {
+	/*
+	 * Gregorian calendar.
+	 */
+
+	fields->gregorian = 1;
+	year = 1;
+
+	/*
+	 * n = Number of 400-year cycles since 1 January, 1 CE in the
+	 * proleptic Gregorian calendar. day = remaining days.
+	 */
+
+	day = jday - JDAY_1_JAN_1_CE_GREGORIAN;
+	n = day / FOUR_CENTURIES;
+	day %= FOUR_CENTURIES;
+	if (day < 0) {
+	    day += FOUR_CENTURIES;
+	    n--;
+	}
+	year += 400 * n;
+
+	/*
+	 * n = number of centuries since the start of (year);
+	 * day = remaining days
+	 */
+
+	n = day / ONE_CENTURY_GREGORIAN;
+	day %= ONE_CENTURY_GREGORIAN;
+	if (n > 3) {
+	    /*
+	     * 31 December in the last year of a 400-year cycle.
+	     */
+
+	    n = 3;
+	    day += ONE_CENTURY_GREGORIAN;
+	}
+	year += 100 * n;
+    } else {
+	/*
+	 * Julian calendar.
+	 */
+
+	fields->gregorian = 0;
+	year = 1;
+	day = jday - JDAY_1_JAN_1_CE_JULIAN;
+    }
+
+    /*
+     * n = number of 4-year cycles; days = remaining days.
+     */
+
+    n = day / FOUR_YEARS;
+    day %= FOUR_YEARS;
+    if (day < 0) {
+	day += FOUR_YEARS;
+	n--;
+    }
+    year += 4 * n;
+
+    /*
+     * n = number of years; days = remaining days.
+     */
+
+    n = day / ONE_YEAR;
+    day %= ONE_YEAR;
+    if (n > 3) {
+	/*
+	 * 31 December of a leap year.
+	 */
+
+	n = 3;
+	day += 365;
+    }
+    year += n;
+
+    /*
+     * store era/year/day back into fields.
+     */
+
+    if (year <= 0) {
+	fields->era = BCE;
+	fields->year = 1 - year;
+    } else {
+	fields->era = CE;
+	fields->year = year;
+    }
+    fields->dayOfYear = day + 1;
+}
+
+/*
+ *----------------------------------------------------------------------
+ *
+ * GetMonthDay --
+ *
+ *	Given a date as year and day-of-year, find month and day.
+ *
+ * Results:
+ *	None.
+ *
+ * Side effects:
+ *	Stores 'month' and 'dayOfMonth' in the 'fields' structure.
+ *
+ *----------------------------------------------------------------------
+ */
+
+static void
+GetMonthDay(
+    TclDateFields *fields)	/* Date to convert */
+{
+    int day = fields->dayOfYear;
+    int month;
+    const int *h = hath[IsGregorianLeapYear(fields)];
+
+    for (month = 0; month < 12 && day > h[month]; ++month) {
+	day -= h[month];
+    }
+    fields->month = month+1;
+    fields->dayOfMonth = day;
+}
+
+/*
+ *----------------------------------------------------------------------
+ *
+ * GetJulianDayFromEraYearWeekDay --
+ *
+ *	Given a TclDateFields structure containing era, ISO8601 year, ISO8601
+ *	week, and day of week, computes the Julian Day Number.
+ *
+ * Results:
+ *	None.
+ *
+ * Side effects:
+ *	Stores 'julianDay' in the fields.
+ *
+ *----------------------------------------------------------------------
+ */
+
+static 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;
+
+    /*
+     * Find January 4 in the ISO8601 year, which will always be in week 1.
+     */
+
+    firstWeek.era = fields->era;
+    firstWeek.year = fields->iso8601Year;
+    firstWeek.month = 1;
+    firstWeek.dayOfMonth = 4;
+    GetJulianDayFromEraYearMonthDay(&firstWeek, changeover);
+
+    /*
+     * Find Monday of week 1.
+     */
+
+    firstMonday = WeekdayOnOrBefore(1, firstWeek.julianDay);
+
+    /*
+     * Advance to the given week and day.
+     */
+
+    fields->julianDay = firstMonday + 7 * (fields->iso8601Week - 1)
+	    + fields->dayOfWeek - 1;
+}
+
+/*
+ *----------------------------------------------------------------------
+ *
+ * GetJulianDayFromEraYearMonthDay --
+ *
+ *	Given era, year, month, and dayOfMonth (in TclDateFields), and the
+ *	Gregorian transition date, computes the Julian Day Number.
+ *
+ * Results:
+ *	None.
+ *
+ * Side effects:
+ *	Stores day number in 'julianDay'
+ *
+ *----------------------------------------------------------------------
+ */
+
+static 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) {
+	year = 1 - fields->year;
+    } else {
+	year = fields->year;
+    }
+
+    /*
+     * Reduce month modulo 12.
+     */
+
+    month = fields->month;
+    mm1 = month - 1;
+    q = mm1 / 12;
+    r = (mm1 % 12);
+    if (r < 0) {
+	r += 12;
+	q -= 1;
+    }
+    year += q;
+    month = r + 1;
+    ym1 = year - 1;
+
+    /*
+     * Adjust the year after reducing the month.
+     */
+
+    fields->gregorian = 1;
+    if (year < 1) {
+	fields->era = BCE;
+	fields->year = 1-year;
+    } else {
+	fields->era = CE;
+	fields->year = year;
+    }
+
+    /*
+     * Try an initial conversion in the Gregorian calendar.
+     */
+
+#if 0 /* BUG http://core.tcl.tk/tcl/tktview?name=da340d4f32 */
+    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;
+    else {
+	ym1o4 = - (int) (((unsigned int) -ym1) / 4);
+    }
+#endif
+    if (ym1 % 4 < 0) {
+	ym1o4--;
+    }
+    ym1o100 = ym1 / 100;
+    if (ym1 % 100 < 0) {
+	ym1o100--;
+    }
+    ym1o400 = ym1 / 400;
+    if (ym1 % 400 < 0) {
+	ym1o400--;
+    }
+    fields->julianDay = JDAY_1_JAN_1_CE_GREGORIAN - 1
+	    + fields->dayOfMonth
+	    + daysInPriorMonths[IsGregorianLeapYear(fields)][month - 1]
+	    + (ONE_YEAR * ym1)
+	    + ym1o4
+	    - ym1o100
+	    + ym1o400;
+
+    /*
+     * If the resulting date is before the Gregorian changeover, convert in
+     * the Julian calendar instead.
+     */
+
+    if (fields->julianDay < changeover) {
+	fields->gregorian = 0;
+	fields->julianDay = JDAY_1_JAN_1_CE_JULIAN - 1
+		+ fields->dayOfMonth
+		+ daysInPriorMonths[year%4 == 0][month - 1]
+		+ (365 * ym1)
+		+ ym1o4;
+    }
+}
+
+/*
+ *----------------------------------------------------------------------
+ *
+ * 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
+IsGregorianLeapYear(
+    TclDateFields *fields)	/* Date to test */
+{
+    int year = fields->year;
+
+    if (fields->era == BCE) {
+	year = 1 - year;
+    }
+    if (year%4 != 0) {
+	return 0;
+    } else if (!(fields->gregorian)) {
+	return 1;
+    } else if (year%400 == 0) {
+	return 1;
+    } else if (year%100 == 0) {
+	return 0;
+    } else {
+	return 1;
+    }
+}
+
+/*
+ *----------------------------------------------------------------------
+ *
+ * WeekdayOnOrBefore --
+ *
+ *	Finds the Julian Day Number of a given day of the week that falls on
+ *	or before a given date, expressed as Julian Day Number.
+ *
+ * Results:
+ *	Returns the Julian Day Number
+ *
+ *----------------------------------------------------------------------
+ */
+
+static int
+WeekdayOnOrBefore(
+    int dayOfWeek,		/* Day of week; Sunday == 0 or 7 */
+    int julianDay)		/* Reference date */
+{
+    int k = (dayOfWeek + 6) % 7;
+    if (k < 0) {
+	k += 7;
+    }
+    return julianDay - ((julianDay - k) % 7);
+}
+
+/*
+ *----------------------------------------------------------------------
+ *
+ * ClockGetenvObjCmd --
+ *
+ *	Tcl command that reads an environment variable from the system
+ *
+ * Usage:
+ *	::tcl::clock::getEnv NAME
+ *
+ * Parameters:
+ *	NAME - Name of the environment variable desired
+ *
+ * Results:
+ *	Returns a standard Tcl result. Returns an error if the variable does
+ *	not exist, with a message left in the interpreter. Returns TCL_OK and
+ *	the value of the variable if the variable does exist,
+ *
+ *----------------------------------------------------------------------
+ */
+
+int
+ClockGetenvObjCmd(
+    ClientData clientData,
+    Tcl_Interp *interp,
+    int objc,
+    Tcl_Obj *const objv[])
+{
+    const char *varName;
+    const char *varValue;
+
+    if (objc != 2) {
+	Tcl_WrongNumArgs(interp, 1, objv, "name");
+	return TCL_ERROR;
+    }
+    varName = TclGetString(objv[1]);
+    varValue = getenv(varName);
+    if (varValue == NULL) {
+	varValue = "";
+    }
+    Tcl_SetObjResult(interp, Tcl_NewStringObj(varValue, -1));
+    return TCL_OK;
+}
+
+/*
+ *----------------------------------------------------------------------
+ *
+ * ThreadSafeLocalTime --
+ *
+ *	Wrapper around the 'localtime' library function to make it thread
+ *	safe.
+ *
+ * Results:
+ *	Returns a pointer to a 'struct tm' in thread-specific data.
+ *
+ * Side effects:
+ *	Invokes localtime or localtime_r as appropriate.
+ *
+ *----------------------------------------------------------------------
+ */
+
+static struct tm *
+ThreadSafeLocalTime(
+    const time_t *timePtr)	/* Pointer to the number of seconds since the
+				 * local system's epoch */
+{
+    /*
+     * Get a thread-local buffer to hold the returned time.
+     */
+
+    struct tm *tmPtr = Tcl_GetThreadData(&tmKey, sizeof(struct tm));
+#ifdef HAVE_LOCALTIME_R
+    localtime_r(timePtr, tmPtr);
+#else
+    struct tm *sysTmPtr;
+
+    Tcl_MutexLock(&clockMutex);
+    sysTmPtr = localtime(timePtr);
+    if (sysTmPtr == NULL) {
+	Tcl_MutexUnlock(&clockMutex);
+	return NULL;
+    }
+    memcpy(tmPtr, localtime(timePtr), sizeof(struct tm));
+    Tcl_MutexUnlock(&clockMutex);
+#endif
+    return tmPtr;
+}
+
+/*----------------------------------------------------------------------
+ *
+ * ClockClicksObjCmd --
+ *
+ *	Returns a high-resolution counter.
+ *
+ * Results:
+ *	Returns a standard Tcl result.
+ *
+ * Side effects:
+ *	None.
+ *
+ * This function implements the 'clock clicks' Tcl command. Refer to the user
+ * documentation for details on what it does.
+ *
+ *----------------------------------------------------------------------
+ */
+
+int
+ClockClicksObjCmd(
+    ClientData clientData,	/* Client data is unused */
+    Tcl_Interp *interp,		/* Tcl interpreter */
+    int objc,			/* Parameter count */
+    Tcl_Obj *const *objv)	/* Parameter values */
+{
+    static const char *const clicksSwitches[] = {
+	"-milliseconds", "-microseconds", NULL
+    };
+    enum ClicksSwitch {
+	CLICKS_MILLIS, CLICKS_MICROS, CLICKS_NATIVE
+    };
+    int index = CLICKS_NATIVE;
+    Tcl_Time now;
+    Tcl_WideInt clicks = 0;
+
+    switch (objc) {
+    case 1:
+	break;
+    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?");
+	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;
+	break;
+    }
+
+    Tcl_SetObjResult(interp, Tcl_NewWideIntObj(clicks));
+    return TCL_OK;
+}
+
+/*----------------------------------------------------------------------
+ *
+ * ClockMillisecondsObjCmd -
+ *
+ *	Returns a count of milliseconds since the epoch.
+ *
+ * Results:
+ *	Returns a standard Tcl result.
+ *
+ * Side effects:
+ *	None.
+ *
+ * This function implements the 'clock milliseconds' Tcl command. Refer to the
+ * user documentation for details on what it does.
+ *
+ *----------------------------------------------------------------------
+ */
+
+int
+ClockMillisecondsObjCmd(
+    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);
+	return TCL_ERROR;
+    }
+    Tcl_GetTime(&now);
+    Tcl_SetObjResult(interp, Tcl_NewWideIntObj((Tcl_WideInt)
+	    now.sec * 1000 + now.usec / 1000));
+    return TCL_OK;
+}
+
+/*----------------------------------------------------------------------
+ *
+ * ClockMicrosecondsObjCmd -
+ *
+ *	Returns a count of microseconds since the epoch.
+ *
+ * Results:
+ *	Returns a standard Tcl result.
+ *
+ * Side effects:
+ *	None.
+ *
+ * This function implements the 'clock microseconds' Tcl command. Refer to the
+ * user documentation for details on what it does.
+ *
+ *----------------------------------------------------------------------
+ */
+
+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);
+	return TCL_ERROR;
+    }
+    Tcl_GetTime(&now);
+    Tcl_SetObjResult(interp, Tcl_NewWideIntObj(
+	    ((Tcl_WideInt) now.sec * 1000000) + now.usec));
+    return TCL_OK;
+}
+
+/*
+ *-----------------------------------------------------------------------------
+ *
+ * ClockParseformatargsObjCmd --
+ *
+ *	Parses the arguments for [clock format].
+ *
+ * Results:
+ *	Returns a standard Tcl result, whose value is a four-element list
+ *	comprising the time format, the locale, and the timezone.
+ *
+ * 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
+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]
+    int gmtFlag = 0;
+    static const char *const options[] = { /* Command line options expected */
+	"-format",	"-gmt",		"-locale",
+	"-timezone",	NULL };
+    enum optionInd {
+	CLOCK_FORMAT_FORMAT,	CLOCK_FORMAT_GMT,	CLOCK_FORMAT_LOCALE,
+	CLOCK_FORMAT_TIMEZONE
+    };
+    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;
+
+    /*
+     * Args consist of a time followed by keyword-value pairs.
+     */
+
+    if (objc < 2 || (objc % 2) != 0) {
+	Tcl_WrongNumArgs(interp, 0, objv,
+		"clock format clockval ?-format string? "
+		"?-gmt boolean? ?-locale LOCALE? ?-timezone ZONE?");
+	Tcl_SetErrorCode(interp, "CLOCK", "wrongNumArgs", NULL);
+	return TCL_ERROR;
+    }
+
+    /*
+     * 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) {
+	if (Tcl_GetIndexFromObj(interp, objv[i], options, "option", 0,
+		&optionIndex) != TCL_OK) {
+	    Tcl_SetErrorCode(interp, "CLOCK", "badOption",
+		    Tcl_GetString(objv[i]), NULL);
+	    return TCL_ERROR;
+	}
+	switch (optionIndex) {
+	case CLOCK_FORMAT_FORMAT:
+	    formatObj = objv[i+1];
+	    break;
+	case CLOCK_FORMAT_GMT:
+	    if (Tcl_GetBooleanFromObj(interp, objv[i+1], &gmtFlag) != TCL_OK){
+		return TCL_ERROR;
+	    }
+	    break;
+	case CLOCK_FORMAT_LOCALE:
+	    localeObj = objv[i+1];
+	    break;
+	case CLOCK_FORMAT_TIMEZONE:
+	    timezoneObj = objv[i+1];
+	    break;
+	}
+	saw |= 1 << optionIndex;
+    }
+
+    /*
+     * Check options.
+     */
+
+    if (TclGetWideIntFromObj(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]);
+	Tcl_SetErrorCode(interp, "CLOCK", "gmtWithTimezone", NULL);
+	return TCL_ERROR;
+    }
+    if (gmtFlag) {
+	timezoneObj = litPtr[LIT_GMT];
+    }
+
+    /*
+     * Return options as a list.
+     */
+
+    Tcl_SetObjResult(interp, Tcl_NewListObj(3, results));
+    return TCL_OK;
+
+#undef timezoneObj
+#undef localeObj
+#undef formatObj
+}
+
+/*----------------------------------------------------------------------
+ *
+ * ClockSecondsObjCmd -
+ *
+ *	Returns a count of microseconds since the epoch.
+ *
+ * Results:
+ *	Returns a standard Tcl result.
+ *
+ * Side effects:
+ *	None.
+ *
+ * This function implements the 'clock seconds' Tcl command. Refer to the user
+ * documentation for details on what it does.
+ *
+ *----------------------------------------------------------------------
+ */
+
+int
+ClockSecondsObjCmd(
+    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);
+	return TCL_ERROR;
+    }
+    Tcl_GetTime(&now);
+    Tcl_SetObjResult(interp, Tcl_NewWideIntObj((Tcl_WideInt) now.sec));
+    return TCL_OK;
+}
+
+/*
+ *----------------------------------------------------------------------
+ *
+ * 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 char* tzWas = INT2PTR(-1);	/* Previous value of TZ, protected by
+				 * clockMutex. */
+    const char *tzIsNow;	/* Current value of TZ */
+
+    Tcl_MutexLock(&clockMutex);
+    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);
+    } else if (tzIsNow == NULL && tzWas != NULL) {
+	tzset();
+	if (tzWas != INT2PTR(-1)) ckfree(tzWas);
+	tzWas = NULL;
+    }
+    Tcl_MutexUnlock(&clockMutex);
+}
+
+/*
+ *----------------------------------------------------------------------
+ *
+ * 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]);
+	}
+	ckfree(data->literals);
+	ckfree(data);
+    }
+}
+
+/*
+ * Local Variables:
+ * mode: c
+ * c-basic-offset: 4
+ * fill-column: 78
+ * End:
+ */