Experimental Physics and
Industrial Control System

Benjamin Franksen <[email protected]> · Mon, 4 Aug 2014 12:00:04 +0200

On Thursday 31 July 2014 10:34:31 Michael Davidsaver wrote:
> I'm working on some changes to link parsing (to facilitate some
> further changes to DB locking).  In doing on this I've come across
> some behaviors of the present implementation which I'd like to change
> (see the numbers below).  I don't think these would have break
> existing code outside Base, but would appreciate being corrected on
> this point.
>
> At present handling of INP/OUT links during initialization is
> complicated it is done as the .db file is parsed, so the DTYP field
> may not be known yet.
>
> I'd like to defer initial parsing of links from its present location
> under dbLoadRecords() to an early stage of iocInit() before
> record/driver/dset initialization and autosave pass0.
>
> 1) This would mean that the value union in DBLINK would remain
> uninitialized until iocInit().
>
> This will greatly simplify things by eliminating the seemingly
> circular relationship between dbPutString() and setLinkType().
>
> 2) A pleasant side effect of these changes is that syntax errors (eg.
> forgetting '#') in HW link fields will be detected and failed before
> the link field is modified.  Currently this fails, but after the
> current device support is detached.
>
> 3) I find that at present omitting a '@' from an INST_IO link will
> succeed, but an empty string is stored.  I'd like to change this to
> fail.
>
> Presently, a syntactically incorrect INP/OUT link in a .db file will
> result in a partially initialized link being seen by device support.
> For example, setting "#C41" for a VME_IO link will result in only the
> signal member for struct vmeio being set to a non-zero value.
>
> 4) I think the device support should see only an "empty" link (correct
> type with all zeros and empty parm string) if INP/OUT is omitted or
> syntactically incorrect.
>
> 6) Further, I'd like to add a field to the DBLINK structure to
> indicate whether it has been correctly initialized to a non-default
> value. Device support can then test this.

This all sounds very sensible to me. I can see no problems arising from
such a change.

So, a thick +1.

Cheers
Ben
--
"Make it so they have to reboot after every typo." â€• Scott Adams

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Experimental Physics and Industrial Control System

Experimental Physics and
Industrial Control System