Experimental Physics and
Industrial Control System

Thomas Birke <[email protected]> · Wed, 04 Feb 2009 12:32:22 +0100

Thomas Birke wrote:

Since the INDX actually has nothing to do with the subArray-record

itself, but is just an index into the referenced waveform (of unknown

size), to me it makes no sense at all to limit INDX to MALM-1.

For me the only solution is to set MALM of my subArray to INDX+NELM

which leads to hundreds of oversized and allocated arrays in my

subArray-records.

E.g. to slice out the last element of a waveform, I have to

(statically!) allocate space for the whole source-waveform and then

copy exactly one element.

I simply ask to drop these 4 lines of code from subArrayRecord.c - it

shouldn't even break existing installations, and for my case I could

reduce memory-consumption a lot.

Ooops - I just found, that this has been discussed before (back in 2005,

see http://www.aps.anl.gov/epics/tech-talk/2005/msg00924.php).

I should have looked at the tech-talk archives before, sorry...

The problem is, that you actually can't index into the source-waveform.

Values retrieved always range from index 0 to <n>.

Maybe we should at least point out this behaviour in the Record

Reference Manual. It's not only NELM that must not be greater that MALM,

but also INDX+NELM always must be less or equal MALM, otherwise NORD

will be less then NELM.

Regards,
Thomas

--
Thomas Birke
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Experimental Physics and Industrial Control System

Experimental Physics and
Industrial Control System