Guardian Procedure Calls Reference Manual

tuid
output
INT:ref:1
is a time-update ID. This is used when calling the SYSTEMCLOCK_SET_ or SETSYSTEMCLOCK
procedure with relative GMT. See the SYSTEMCLOCK_SET_ Procedure (page 1408).
error
output
INT:ref:1
is returned only from a remote system with one exception: a value of -1 is returned when type
is out of range.
node
input
INT:value
is the system number of the remote node from which you want the timestamp. A value of -1
indicates that this parameter is not present and that the current node is used.
Returned Value
FIXED
A value representing the number of microseconds since 12:00 (noon) GMT (Julian proleptic
calender) January 1, 4713 B.C., unless type = 3. To convert this retval to a more usable form,
use the INTERPRETTIMESTAMP procedure.
If type = 3, the value returned is the number of microseconds since the last system load. To convert
this retval to a more usable form, use the INTERPRETINTERVAL procedure.
Considerations
• System message -10 (SETTIME) allows processes to determine the magnitude of and the reason
for a time change. For descriptions of interprocess system messages sent to processes, see the
Guardian Procedure Errors and Messages Manual.
• A 64-bit Julian timestamp is based on the Julian date. It is a quantity equal to the number of
microseconds since 12:00 (noon) Greenwich mean time (Julian proleptic calendar) January
1, 4713 B.C. This timestamp can represent either Greenwich mean time, local standard time,
or local civil time. There is no way to examine a Julian timestamp and determine which of the
three times it represents.
Procedures that work with a 64-bit Julian timestamp are COMPUTETIMESTAMP,
CONVERTTIMESTAMP, INTERPRETTIMESTAMP, JULIANTIMESTAMP, and
SYSTEMCLOCK_SET_/SETSYSTEMCLOCK. Where possible, it is recommended that
applications use these procedures rather than the procedures that work with 48-bit timestamps.
• A 48-bit timestamp is a quantity equal to the number of 10-millisecond units since 00:00, 31
December 1974. The 48-bit timestamp always represents local civil time (wall clock time);
consequently, this value is affected by standard time/daylight saving time changes and time
zone differences.
Procedures that work with a 48-bit timestamp are: CONTIME, TIME, and TIMESTAMP.
• Process creation time is initialized by calling TIMESTAMP, which returns the local civil time in
centiseconds (0.01 second = 10 milliseconds) since midnight (00:00) on 31 December 1974,
in an array of three words. Only the two low-order words are saved in the process control
block (PCB); this is sufficient to make the unnamed process ID unique.
• The RCLK instruction ($READCLOCK in TAL) is another source of timestamps. It returns a 64-bit
timestamp representing the local civil time in microseconds since midnight (00:00) on 31
748 Guardian Procedure Calls (H-K)