Experimental Physics and
Industrial Control System

"Denison, PN \(Peter\)" <[email protected]> · Thu, 1 Nov 2007 11:37:50 -0000

I'm having a little trouble using epicsTimeDiffInSeconds().
src/libCom/osi/epicsTime.cpp:970 in R3.14.9

Whilst it should be straightforward, I'm getting some strange results
that I hope someone can shed light on.

The trace below is triggered when epicsTimeDiffInSeconds(new, last)
returns a -ve number. I've printed the secsSinceEpoch and nsec fields of
each of the epicsTimeStamp structures. 'diff' is the return value from
the function call. I've also printed DBL_MAX, which should be
1.7976931348623157e+308, but isn't.

0x1ec5ab00 (scan0.1): TCP provider "MRF EVR" provides backwards time!
new = 562760425s, 0ns, last = 562760425s, 983327000ns
diff=-2.28999e+226
0x1ec5ab00 (scan0.1): DBL_MAX is -2.28999e+226
0x1ec48800 (timerQueue): TCP provider "MRF EVR" provides backwards time!
new = 562760479s, 583936000ns, last = 562760479s, 583937000ns
diff=-2.28999e+226
0x1ec48800 (timerQueue): DBL_MAX is -2.28999e+226

It appears that there are two problems: 1) somewhere in the bowels of
the construction of 2 C++ objects, and calling operator- there is an
exception being raised, causing the function to return -DBL_MAX. 2)
Somehow the vxWorks compiler (gcc 2.96) is failing to represent DBL_MAX
properly.

Any clues? I'm sure there were very good reasons to do all the time code
in C++, but it seems to be confusing rather than helping at the moment.

-- 
Peter Denison, Senior Software Engineer, Diamond Light Source Ltd.
Tel: +44 1235 778511
(apologies in advance for the lines below. Some bits are a legal
requirement and I have no control over them)

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Experimental Physics and Industrial Control System

Experimental Physics and
Industrial Control System