/*
 * Scale to convert wide click values from the TclpGetWideClicks native
 * resolution to microsecond resolution and back.
 */
static struct {
    int initialized;		/* 1 if initialized, 0 otherwise */
    int perfCounter;		/* 1 if performance counter usable for wide
				 * clicks */
    double microsecsScale;	/* Denominator scale between clock / microsecs */
} wideClick = {0, 0, 0.0};


/*
 * Declarations for functions defined later in this file.
 */

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

	    timeInfo.perfCounterAvailable =
		    QueryPerformanceFrequency(&timeInfo.nominalFreq);

	    /*

	curCounterFreq = timeInfo.curCounterFreq.QuadPart;

	LeaveCriticalSection(&timeInfo.cs);

	/*
	 * If calibration cycle occurred after we get curCounter
	 */

	if (curCounter.QuadPart <= perfCounterLastCall) {
	    /*
	     * Calibrated file-time is saved from posix in 100-ns ticks
	     */

	    return fileTimeLastCall / 10;
	}

	/*
	 * If it appears to be more than 1.1 seconds since the last trip
	 * through the calibration loop, the performance counter may have
	 * jumped forward. (See MSDN Knowledge Base article Q274323 for a

	waitResult = WaitForSingleObjectEx(timeInfo.exitEvent, 1000, FALSE);
	if (waitResult == WAIT_OBJECT_0) {
	    break;
	}
	UpdateTimeEachSecond();
    }


    return (DWORD) 0;
}

/*
 *----------------------------------------------------------------------
 *
 * UpdateTimeEachSecond --

static void
UpdateTimeEachSecond(void)
{
    LARGE_INTEGER curPerfCounter;
				/* Current value returned from
				 * QueryPerformanceCounter. */
    FILETIME curSysTime;	/* Current system time. */
    static LARGE_INTEGER lastFileTime;
				/* File time of the previous calibration */
    LARGE_INTEGER curFileTime;	/* File time at the time this callback was
				 * scheduled. */
    Tcl_WideInt estFreq;	/* Estimated perf counter frequency. */
    Tcl_WideInt vt0;		/* Tcl time right now. */
    Tcl_WideInt vt1;		/* Tcl time one second from now. */
    Tcl_WideInt tdiff;		/* Difference between system clock and Tcl
				 * time. */