tclwintime.c

这是leon3处理器的交叉编译链

/* 
 * tclWinTime.c --
 *
 *	Contains Windows specific versions of Tcl functions that
 *	obtain time values from the operating system.
 *
 * Copyright 1995-1998 by Sun Microsystems, Inc.
 *
 * See the file "license.terms" for information on usage and redistribution
 * of this file, and for a DISCLAIMER OF ALL WARRANTIES.
 *
 * RCS: @(#) $Id: tclWinTime.c,v 1.11 2002/10/09 23:57:25 kennykb Exp $
 */

#include "tclWinInt.h"

#define SECSPERDAY (60L * 60L * 24L)
#define SECSPERYEAR (SECSPERDAY * 365L)
#define SECSPER4YEAR (SECSPERYEAR * 4L + SECSPERDAY)

/*
 * The following arrays contain the day of year for the last day of
 * each month, where index 1 is January.
 */

static int normalDays[] = {
    -1, 30, 58, 89, 119, 150, 180, 211, 242, 272, 303, 333, 364
};

static int leapDays[] = {
    -1, 30, 59, 90, 120, 151, 181, 212, 243, 273, 304, 334, 365
};

typedef struct ThreadSpecificData {
    char tzName[64];		/* Time zone name */
    struct tm tm;		/* time information */
} ThreadSpecificData;
static Tcl_ThreadDataKey dataKey;

/*
 * Calibration interval for the high-resolution timer, in msec
 */

static CONST unsigned long clockCalibrateWakeupInterval = 10000;
				/* FIXME: 10 s -- should be about 10 min! */

/*
 * Data for managing high-resolution timers.
 */

typedef struct TimeInfo {

    CRITICAL_SECTION cs;	/* Mutex guarding this structure */

    int initialized;		/* Flag == 1 if this structure is
				 * initialized. */

    int perfCounterAvailable;	/* Flag == 1 if the hardware has a
				 * performance counter */

    HANDLE calibrationThread;	/* Handle to the thread that keeps the
				 * virtual clock calibrated. */

    HANDLE readyEvent;		/* System event used to
				 * trigger the requesting thread
				 * when the clock calibration procedure
				 * is initialized for the first time */
    HANDLE exitEvent; 		/* Event to signal out of an exit handler
				 * to tell the calibration loop to
				 * terminate */


    /*
     * The following values are used for calculating virtual time.
     * Virtual time is always equal to:
     *    lastFileTime + (current perf counter - lastCounter) 
     *				* 10000000 / curCounterFreq
     * and lastFileTime and lastCounter are updated any time that
     * virtual time is returned to a caller.
     */

    ULARGE_INTEGER lastFileTime;
    LARGE_INTEGER lastCounter;
    LARGE_INTEGER curCounterFreq;

    /* 
     * The next two values are used only in the calibration thread, to track
     * the frequency of the performance counter.
     */

    LONGLONG lastPerfCounter;	/* Performance counter the last time
				 * that UpdateClockEachSecond was called */
    LONGLONG lastSysTime;	/* System clock at the last time
				 * that UpdateClockEachSecond was called */
    LONGLONG estPerfCounterFreq;
				/* Current estimate of the counter frequency
				 * using the system clock as the standard */

} TimeInfo;

static TimeInfo timeInfo = {
    { NULL }, 
    0, 
    0, 
    (HANDLE) NULL, 
    (HANDLE) NULL, 
    (HANDLE) NULL, 
    0, 
    0, 
    0, 
    0, 
    0,
    0
};

CONST static FILETIME posixEpoch = { 0xD53E8000, 0x019DB1DE };
    
/*
 * Declarations for functions defined later in this file.
 */

static struct tm *	ComputeGMT _ANSI_ARGS_((const time_t *tp));
static void		StopCalibration _ANSI_ARGS_(( ClientData ));
static DWORD WINAPI     CalibrationThread _ANSI_ARGS_(( LPVOID arg ));
static void 		UpdateTimeEachSecond _ANSI_ARGS_(( void ));

/*
 *----------------------------------------------------------------------
 *
 * TclpGetSeconds --
 *
 *	This procedure returns the number of seconds from the epoch.
 *	On most Unix systems the epoch is Midnight Jan 1, 1970 GMT.
 *
 * Results:
 *	Number of seconds from the epoch.
 *
 * Side effects:
 *	None.
 *
 *----------------------------------------------------------------------
 */

unsigned long
TclpGetSeconds()
{
    Tcl_Time t;
    Tcl_GetTime( &t );
    return t.sec;
}

/*
 *----------------------------------------------------------------------
 *
 * TclpGetClicks --
 *
 *	This procedure returns a value that represents the highest
 *	resolution clock available on the system.  There are no
 *	guarantees on what the resolution will be.  In Tcl we will
 *	call this value a "click".  The start time is also system
 *	dependant.
 *
 * Results:
 *	Number of clicks from some start time.
 *
 * Side effects:
 *	None.
 *
 *----------------------------------------------------------------------
 */

unsigned long
TclpGetClicks()
{
    /*
     * Use the Tcl_GetTime abstraction to get the time in microseconds,
     * as nearly as we can, and return it.
     */

    Tcl_Time now;		/* Current Tcl time */
    unsigned long retval;	/* Value to return */

    Tcl_GetTime( &now );
    retval = ( now.sec * 1000000 ) + now.usec;
    return retval;

}

/*
 *----------------------------------------------------------------------
 *
 * TclpGetTimeZone --
 *
 *	Determines the current timezone.  The method varies wildly
 *	between different Platform implementations, so its hidden in
 *	this function.
 *
 * Results:
 *	Minutes west of GMT.
 *
 * Side effects:
 *	None.
 *
 *----------------------------------------------------------------------
 */

int
TclpGetTimeZone (currentTime)
    unsigned long  currentTime;
{
    int timeZone;

    tzset();
    timeZone = _timezone / 60;

    return timeZone;
}

/*
 *----------------------------------------------------------------------
 *
 * Tcl_GetTime --
 *
 *	Gets the current system time in seconds and microseconds
 *	since the beginning of the epoch: 00:00 UCT, January 1, 1970.
 *
 * Results:
 *	Returns the current time in timePtr.
 *
 * Side effects:
 *	On the first call, initializes a set of static variables to
 *	keep track of the base value of the performance counter, the
 *	corresponding wall clock (obtained through ftime) and the
 *	frequency of the performance counter.  Also spins a thread
 *	whose function is to wake up periodically and monitor these
 *	values, adjusting them as necessary to correct for drift
 *	in the performance counter's oscillator.
 *
 *----------------------------------------------------------------------
 */

void
Tcl_GetTime(timePtr)
    Tcl_Time *timePtr;		/* Location to store time information. */
{
	
    struct timeb t;

    /* Initialize static storage on the first trip through. */

    /*
     * Note: Outer check for 'initialized' is a performance win
     * since it avoids an extra mutex lock in the common case.
     */

    if ( !timeInfo.initialized ) { 
	TclpInitLock();
	if ( !timeInfo.initialized ) {
	    timeInfo.perfCounterAvailable
		= QueryPerformanceFrequency( &timeInfo.curCounterFreq );

	    /*
	     * Some hardware abstraction layers use the CPU clock
	     * in place of the real-time clock as a performance counter
	     * reference.  This results in:
	     *    - inconsistent results among the processors on
	     *      multi-processor systems.
	     *    - unpredictable changes in performance counter frequency
	     *      on "gearshift" processors such as Transmeta and
	     *      SpeedStep.
	     *
	     * There seems to be no way to test whether the performance
	     * counter is reliable, but a useful heuristic is that
	     * if its frequency is 1.193182 MHz or 3.579545 MHz, it's
	     * derived from a colorburst crystal and is therefore
	     * the RTC rather than the TSC.
	     *
	     * A sloppier but serviceable heuristic is that the RTC crystal
	     * is normally less than 15 MHz while the TSC crystal is
	     * virtually assured to be greater than 100 MHz.  Since Win98SE
	     * appears to fiddle with the definition of the perf counter
	     * frequency (perhaps in an attempt to calibrate the clock?)
	     * we use the latter rule rather than an exact match.
	     */

	    if ( timeInfo.perfCounterAvailable
		 /* The following lines would do an exact match on
		  * crystal frequency:
		  * && timeInfo.curCounterFreq.QuadPart != (LONGLONG) 1193182
		  * && timeInfo.curCounterFreq.QuadPart != (LONGLONG) 3579545
		  */
		 && timeInfo.curCounterFreq.QuadPart > (LONGLONG) 15000000 ) {
		timeInfo.perfCounterAvailable = FALSE;
	    }

	    /*
	     * If the performance counter is available, start a thread to
	     * calibrate it.
	     */

	    if ( timeInfo.perfCounterAvailable ) {
		DWORD id;
		InitializeCriticalSection( &timeInfo.cs );
		timeInfo.readyEvent = CreateEvent( NULL, FALSE, FALSE, NULL );
		timeInfo.exitEvent = CreateEvent( NULL, FALSE, FALSE, NULL );
		timeInfo.calibrationThread = CreateThread( NULL,
							   8192,
							   CalibrationThread,
							   (LPVOID) NULL,
							   0,
							   &id );
		SetThreadPriority( timeInfo.calibrationThread,
				   THREAD_PRIORITY_HIGHEST );

		/*
		 * Wait for the thread just launched to start running,
		 * and create an exit handler that kills it so that it
		 * doesn't outlive unloading tclXX.dll
		 */

		WaitForSingleObject( timeInfo.readyEvent, INFINITE );
		CloseHandle( timeInfo.readyEvent );
		Tcl_CreateExitHandler( StopCalibration, (ClientData) NULL );
	    }
	    timeInfo.initialized = TRUE;
	}
	TclpInitUnlock();
    }

    if ( timeInfo.perfCounterAvailable ) {
	
	/*
	 * Query the performance counter and use it to calculate the
	 * current time.
	 */

	LARGE_INTEGER curCounter;
				/* Current performance counter */

	LONGLONG curFileTime;
				/* Current estimated time, expressed
				 * as 100-ns ticks since the Windows epoch */

	static LARGE_INTEGER posixEpoch;
				/* Posix epoch expressed as 100-ns ticks
				 * since the windows epoch */

	LONGLONG usecSincePosixEpoch;
				/* Current microseconds since Posix epoch */

	posixEpoch.LowPart = 0xD53E8000;
	posixEpoch.HighPart = 0x019DB1DE;

	EnterCriticalSection( &timeInfo.cs );

	QueryPerformanceCounter( &curCounter );
	curFileTime = timeInfo.lastFileTime.QuadPart
	    + ( ( curCounter.QuadPart - timeInfo.lastCounter.QuadPart )
		* 10000000 / timeInfo.curCounterFreq.QuadPart );
	timeInfo.lastFileTime.QuadPart = curFileTime;
	timeInfo.lastCounter.QuadPart = curCounter.QuadPart;
	usecSincePosixEpoch = ( curFileTime - posixEpoch.QuadPart ) / 10;
	timePtr->sec = (time_t) ( usecSincePosixEpoch / 1000000 );
	timePtr->usec = (unsigned long ) ( usecSincePosixEpoch % 1000000 );
	
	LeaveCriticalSection( &timeInfo.cs );

	
    } else {
	
	/* High resolution timer is not available.  Just use ftime */
	
	ftime(&t);
	timePtr->sec = t.time;
	timePtr->usec = t.millitm * 1000;
    }
}

/*
 *----------------------------------------------------------------------
 *
 * StopCalibration --
 *
 *	Turns off the calibration thread in preparation for exiting the
 *	process.
 *
 * Results:
 *	None.
 *
 * Side effects:
 *	Sets the 'exitEvent' event in the 'timeInfo' structure to ask
 *	the thread in question to exit, and waits for it to do so.
 *
 *----------------------------------------------------------------------
 */

static void
StopCalibration( ClientData unused )
				/* Client data is unused */
{
    SetEvent( timeInfo.exitEvent );
    WaitForSingleObject( timeInfo.calibrationThread, INFINITE );
    CloseHandle( timeInfo.exitEvent );
    CloseHandle( timeInfo.calibrationThread );
}

/*
 *----------------------------------------------------------------------
 *
 * TclpGetTZName --
 *
 *	Gets the current timezone string.
 *
 * Results:
 *	Returns a pointer to a static string, or NULL on failure.
 *
 * Side effects:
 *	None.
 *
 *----------------------------------------------------------------------
 */

char *
TclpGetTZName(int dst)
{
    int len;
    char *zone, *p;
    TIME_ZONE_INFORMATION tz;
    Tcl_Encoding encoding;
    ThreadSpecificData *tsdPtr = TCL_TSD_INIT(&dataKey);
    char *name = tsdPtr->tzName;

    /*
     * tzset() under Borland doesn't seem to set up tzname[] at all.
     * tzset() under MSVC has the following weird observed behavior:
     *	 First time we call "clock format [clock seconds] -format %Z -gmt 1"
     *	 we get "GMT", but on all subsequent calls we get the current time 
     *	 zone string, even though env(TZ) is GMT and the variable _timezone 
     *   is 0.
     */

    name[0] = '\0';

    zone = getenv("TZ");
    if (zone != NULL) {
	/*
	 * TZ is of form "NST-4:30NDT", where "NST" would be the
	 * name of the standard time zone for this area, "-4:30" is
	 * the offset from GMT in hours, and "NDT is the name of 
	 * the daylight savings time zone in this area.  The offset 
	 * and DST strings are optional.
	 */

	len = strlen(zone);
	if (len > 3) {
	    len = 3;
	}
	if (dst != 0) {
	    /*