epicsTimeLoadTimeInit Class Reference

Public Member Functions
	epicsTimeLoadTimeInit ()

Public Attributes
double	epicsEpochOffset
double	time_tSecPerTick
unsigned long	epicsEpochOffsetAsAnUnsignedLong
bool	useDiffTimeOptimization

Detailed Description

Definition at line 74 of file epicsTime.cpp.

Constructor & Destructor Documentation

epicsTimeLoadTimeInit::epicsTimeLoadTimeInit

(

)

Definition at line 86 of file epicsTime.cpp.

{
    // All we know about time_t is that it is an arithmetic type.
    time_t t_zero = static_cast<time_t> (0);
    time_t t_one  = static_cast<time_t> (1);
    this->time_tSecPerTick = difftime (t_one, t_zero);

    /* The EPICS epoch (1/1/1990 00:00:00UTC) was 631152000 seconds after
     * the ANSI epoch (1/1/1970 00:00:00UTC)
     * Convert this offset into time_t units, however this must not be
     * calculated using local time (i.e. using mktime() or similar), since
     * in the UK the ANSI Epoch had daylight saving time in effect, and
     * the value calculated would be 3600 seconds wrong.*/
    this->epicsEpochOffset =
        (double) POSIX_TIME_AT_EPICS_EPOCH / this->time_tSecPerTick;

    if (this->time_tSecPerTick == 1.0 &&
        this->epicsEpochOffset <= ULONG_MAX &&
        this->epicsEpochOffset >= 0) {
        // We can use simpler code on Posix-compliant systems
        this->useDiffTimeOptimization = true;
        this->epicsEpochOffsetAsAnUnsignedLong =
            static_cast<unsigned long>(this->epicsEpochOffset);
    } else {
        // Forced to use the slower but correct code
        this->useDiffTimeOptimization = false;
        this->epicsEpochOffsetAsAnUnsignedLong = 0;
    }
}

Member Data Documentation

double epicsTimeLoadTimeInit::epicsEpochOffset

Definition at line 77 of file epicsTime.cpp.

unsigned long epicsTimeLoadTimeInit::epicsEpochOffsetAsAnUnsignedLong

Definition at line 79 of file epicsTime.cpp.

double epicsTimeLoadTimeInit::time_tSecPerTick

Definition at line 78 of file epicsTime.cpp.

bool epicsTimeLoadTimeInit::useDiffTimeOptimization

Definition at line 80 of file epicsTime.cpp.

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The documentation for this class was generated from the following file:

• modules/libcom/src/osi/epicsTime.cpp