Experimental Physics and
Industrial Control System

Andrew Johnson <[email protected]> · Fri, 11 May 2007 16:13:04 -0500

Hi Ralph,
Ralph Lange wrote:

As the VxWorks strftime() does not support "%s" (seconds since the
epoch), is there another reasonable way to get this number from the
timestamp of a record into the value field of the same (or another) record?

Interesting question; I can't think of any _reasonable_ ways that don't
involve writing some C code -- there is an unreasonable way to do it
without coding, but it would be quite a sight to see!
The simplest way is to use a subroutine record, the TSEL link of the
record should point to the TIME field of the record whose timestamp you
want to know. The subroutine code is just:
void timeSubroutine(subRecord *prec) {
    recGblGetTimeStamp(prec);
    prec->val = prec->time.secPastEpoch;
}
If you want the full nanosecond accuracy, or need to adjust the epoch
you could use some variant of this code:
void timeSubroutine(subRecord *prec) {
    epicsTimeStamp epoch = {0, 0};	/* Jeff won't like this! */
    recGblGetTimeStamp(prec);
    prec->val = epicsTimeDiffInSeconds(&prec->time, &epoch);
}
Of course you could also do this within an ai device support instead,
but the subroutine record code can be used in as many record instances
as you need.
- Andrew
--
The right to be heard does not automatically include
the right to be taken seriously. -- Hubert H. Humphrey

Experimental Physics and Industrial Control System

Experimental Physics and
Industrial Control System