/* * 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: @(#) tclWinTime.c,v 1.5 2003/01/21 19:40:23 hunt 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) { /* * Skip the offset string and get the DST string. */ p = zone + len; p += strspn(p, "+-:0123456789"); if (*p != '\0') { zone = p; len = strlen(zone); if (len > 3) { len = 3; } } } Tcl_ExternalToUtf(NULL, NULL, zone, len, 0, NULL, name, sizeof(tsdPtr->tzName), NULL, NULL, NULL); } if (name[0] == '\0') { if (GetTimeZoneInformation(&tz) == TIME_ZONE_ID_UNKNOWN) { /* * MSDN: On NT this is returned if DST is not used in * the current TZ */ dst = 0; } encoding = Tcl_GetEncoding(NULL, "unicode"); Tcl_ExternalToUtf(NULL, encoding, (char *) ((dst) ? tz.DaylightName : tz.StandardName), -1, 0, NULL, name, sizeof(tsdPtr->tzName), NULL, NULL, NULL); Tcl_FreeEncoding(encoding); } return name; } /* *---------------------------------------------------------------------- * * TclpGetDate -- * * This function converts between seconds and struct tm. If * useGMT is true, then the returned date will be in Greenwich * Mean Time (GMT). Otherwise, it will be in the local time zone. * * Results: * Returns a static tm structure. * * Side effects: * None. * *---------------------------------------------------------------------- */ struct tm * TclpGetDate(t, useGMT) TclpTime_t t; int useGMT; { const time_t *tp = (const time_t *) t; struct tm *tmPtr; long time; if (!useGMT) { tzset(); /* * If we are in the valid range, let the C run-time library * handle it. Otherwise we need to fake it. Note that this * algorithm ignores daylight savings time before the epoch. */ if (*tp >= 0) { return localtime(tp); } time = *tp - _timezone; /* * If we aren't near to overflowing the long, just add the bias and * use the normal calculation. Otherwise we will need to adjust * the result at the end. */ if (*tp < (LONG_MAX - 2 * SECSPERDAY) && *tp > (LONG_MIN + 2 * SECSPERDAY)) { tmPtr = ComputeGMT(&time); } else { tmPtr = ComputeGMT(tp); tzset(); /* * Add the bias directly to the tm structure to avoid overflow. * Propagate seconds overflow into minutes, hours and days. */ time = tmPtr->tm_sec - _timezone; tmPtr->tm_sec = (int)(time % 60); if (tmPtr->tm_sec < 0) { tmPtr->tm_sec += 60; time -= 60; } time = tmPtr->tm_min + time/60; tmPtr->tm_min = (int)(time % 60); if (tmPtr->tm_min < 0) { tmPtr->tm_min += 60; time -= 60; } time = tmPtr->tm_hour + time/60; tmPtr->tm_hour = (int)(time % 24); if (tmPtr->tm_hour < 0) { tmPtr->tm_hour += 24; time -= 24; } time /= 24; tmPtr->tm_mday += time; tmPtr->tm_yday += time; tmPtr->tm_wday = (tmPtr->tm_wday + time) % 7; } } else { tmPtr = ComputeGMT(tp); } return tmPtr; } /* *---------------------------------------------------------------------- * * ComputeGMT -- * * This function computes GMT given the number of seconds since * the epoch (midnight Jan 1 1970). * * Results: * Returns a (per thread) statically allocated struct tm. * * Side effects: * Updates the values of the static struct tm. * *---------------------------------------------------------------------- */ static struct tm * ComputeGMT(tp) const time_t *tp; { struct tm *tmPtr; long tmp, rem; int isLeap; int *days; ThreadSpecificData *tsdPtr = TCL_TSD_INIT(&dataKey); tmPtr = &tsdPtr->tm; /* * Compute the 4 year span containing the specified time. */ tmp = *tp / SECSPER4YEAR; rem = *tp % SECSPER4YEAR; /* * Correct for weird mod semantics so the remainder is always positive. */ if (rem < 0) { tmp--; rem += SECSPER4YEAR; } /* * Compute the year after 1900 by taking the 4 year span and adjusting * for the remainder. This works because 2000 is a leap year, and * 1900/2100 are out of the range. */ tmp = (tmp * 4) + 70; isLeap = 0; if (rem >= SECSPERYEAR) { /* 1971, etc. */ tmp++; rem -= SECSPERYEAR; if (rem >= SECSPERYEAR) { /* 1972, etc. */ tmp++; rem -= SECSPERYEAR; if (rem >= SECSPERYEAR + SECSPERDAY) { /* 1973, etc. */ tmp++; rem -= SECSPERYEAR + SECSPERDAY; } else { isLeap = 1; } } } tmPtr->tm_year = tmp; /* * Compute the day of year and leave the seconds in the current day in * the remainder. */ tmPtr->tm_yday = rem / SECSPERDAY; rem %= SECSPERDAY; /* * Compute the time of day. */ tmPtr->tm_hour = rem / 3600; rem %= 3600; tmPtr->tm_min = rem / 60; tmPtr->tm_sec = rem % 60; /* * Compute the month and day of month. */ days = (isLeap) ? leapDays : normalDays; for (tmp = 1; days[tmp] < tmPtr->tm_yday; tmp++) { } tmPtr->tm_mon = --tmp; tmPtr->tm_mday = tmPtr->tm_yday - days[tmp]; /* * Compute day of week. Epoch started on a Thursday. */ tmPtr->tm_wday = (*tp / SECSPERDAY) + 4; if ((*tp % SECSPERDAY) < 0) { tmPtr->tm_wday--; } tmPtr->tm_wday %= 7; if (tmPtr->tm_wday < 0) { tmPtr->tm_wday += 7; } return tmPtr; } /* *---------------------------------------------------------------------- * * CalibrationThread -- * * Thread that manages calibration of the hi-resolution time * derived from the performance counter, to keep it synchronized * with the system clock. * * Parameters: * arg -- Client data from the CreateThread call. This parameter * points to the static TimeInfo structure. * * Return value: * None. This thread embeds an infinite loop. * * Side effects: * At an interval of clockCalibrateWakeupInterval ms, this thread * performs virtual time discipline. * * Note: When this thread is entered, TclpInitLock has been called * to safeguard the static storage. There is therefore no synchronization * in the body of this procedure. * *---------------------------------------------------------------------- */ static DWORD WINAPI CalibrationThread( LPVOID arg ) { FILETIME curFileTime; DWORD waitResult; /* Get initial system time and performance counter */ GetSystemTimeAsFileTime( &curFileTime ); QueryPerformanceCounter( &timeInfo.lastCounter ); QueryPerformanceFrequency( &timeInfo.curCounterFreq ); timeInfo.lastFileTime.LowPart = curFileTime.dwLowDateTime; timeInfo.lastFileTime.HighPart = curFileTime.dwHighDateTime; /* Initialize the working storage for the calibration callback */ timeInfo.lastPerfCounter = timeInfo.lastCounter.QuadPart; timeInfo.estPerfCounterFreq = timeInfo.curCounterFreq.QuadPart; /* * Wake up the calling thread. When it wakes up, it will release the * initialization lock. */ SetEvent( timeInfo.readyEvent ); /* Run the calibration once a second */ for ( ; ; ) { /* If the exitEvent is set, break out of the loop. */ waitResult = WaitForSingleObjectEx(timeInfo.exitEvent, 1000, FALSE); if ( waitResult == WAIT_OBJECT_0 ) { break; } UpdateTimeEachSecond(); } /* lint */ return (DWORD) 0; } /* *---------------------------------------------------------------------- * * UpdateTimeEachSecond -- * * Callback from the waitable timer in the clock calibration thread * that updates system time. * * Parameters: * info -- Pointer to the static TimeInfo structure * * Results: * None. * * Side effects: * Performs virtual time calibration discipline. * *---------------------------------------------------------------------- */ static void UpdateTimeEachSecond() { LARGE_INTEGER curPerfCounter; /* Current value returned from * QueryPerformanceCounter */ LONGLONG perfCounterDiff; /* Difference between the current value * and the value of 1 second ago */ FILETIME curSysTime; /* Current system time */ LARGE_INTEGER curFileTime; /* File time at the time this callback * was scheduled. */ LONGLONG fileTimeDiff; /* Elapsed time on the system clock * since the last time this procedure * was called */ LONGLONG instantFreq; /* Instantaneous estimate of the * performance counter frequency */ LONGLONG delta; /* Increment to add to the estimated * performance counter frequency in the * loop filter */ LONGLONG fuzz; /* Tolerance for the perf counter frequency */ LONGLONG lowBound; /* Lower bound for the frequency assuming * 1000 ppm tolerance */ LONGLONG hiBound; /* Upper bound for the frequency */ /* * Get current performance counter and system time. */ QueryPerformanceCounter( &curPerfCounter ); GetSystemTimeAsFileTime( &curSysTime ); curFileTime.LowPart = curSysTime.dwLowDateTime; curFileTime.HighPart = curSysTime.dwHighDateTime; EnterCriticalSection( &timeInfo.cs ); /* * Find out how many ticks of the performance counter and the * system clock have elapsed since we got into this procedure. * Estimate the current frequency. */ perfCounterDiff = curPerfCounter.QuadPart - timeInfo.lastPerfCounter; timeInfo.lastPerfCounter = curPerfCounter.QuadPart; fileTimeDiff = curFileTime.QuadPart - timeInfo.lastSysTime; timeInfo.lastSysTime = curFileTime.QuadPart; instantFreq = ( 10000000 * perfCounterDiff / fileTimeDiff ); /* * Consider this a timing glitch if instant frequency varies * significantly from the current estimate. */ fuzz = timeInfo.estPerfCounterFreq >> 10; lowBound = timeInfo.estPerfCounterFreq - fuzz; hiBound = timeInfo.estPerfCounterFreq + fuzz; if ( instantFreq < lowBound || instantFreq > hiBound ) { LeaveCriticalSection( &timeInfo.cs ); return; } /* * Update the current estimate of performance counter frequency. * This code is equivalent to the loop filter of a phase locked * loop. */ delta = ( instantFreq - timeInfo.estPerfCounterFreq ) >> 6; timeInfo.estPerfCounterFreq += delta; /* * Update the current virtual time. */ timeInfo.lastFileTime.QuadPart += ( ( curPerfCounter.QuadPart - timeInfo.lastCounter.QuadPart ) * 10000000 / timeInfo.curCounterFreq.QuadPart ); timeInfo.lastCounter.QuadPart = curPerfCounter.QuadPart; delta = curFileTime.QuadPart - timeInfo.lastFileTime.QuadPart; if ( delta > 10000000 || delta < -10000000 ) { /* * If the virtual time slip exceeds one second, then adjusting * the counter frequency is hopeless (it'll take over fifteen * minutes to line up with the system clock). The most likely * cause of this large a slip is a sudden change to the system * clock, perhaps because it was being corrected by wristwatch * and eyeball. Accept the system time, and set the performance * counter frequency to the current estimate. */ timeInfo.lastFileTime.QuadPart = curFileTime.QuadPart; timeInfo.curCounterFreq.QuadPart = timeInfo.estPerfCounterFreq; } else { /* * Compute a counter frequency that will cause virtual time to line * up with system time one second from now, assuming that the * performance counter continues to tick at timeInfo.estPerfCounterFreq. */ timeInfo.curCounterFreq.QuadPart = 10000000 * timeInfo.estPerfCounterFreq / ( delta + 10000000 ); /* * Limit frequency excursions to 1000 ppm from estimate */ if ( timeInfo.curCounterFreq.QuadPart < lowBound ) { timeInfo.curCounterFreq.QuadPart = lowBound; } else if ( timeInfo.curCounterFreq.QuadPart > hiBound ) { timeInfo.curCounterFreq.QuadPart = hiBound; } } LeaveCriticalSection( &timeInfo.cs ); }