Experimental Physics and
Industrial Control System

Marty Kraimer <[email protected]> · Thu, 16 Jun 2005 10:34:05 -0500

Benjamin Franksen wrote:

Hello,

I must say that I strongly agree with most of Jeff's arguments. (Maybe

not so much the 'unsigned' story, but practically everything else).

The current definition of epicsTypes does NOT include unsigned types.

The reason is Java. If we allow unsigned types it makes it very

difficult to complely support Java.

The only place we see that V3 epics records need unsigned is for bit masks.

However there is a big problem with the mask fields in the the mbbXXX

records.

The mask field is 32 bits. How do we handle a 64 bit I/O module?
OK with V4 we can make the mask fields be 64 bits.
But how do we handle a 128 digital I/O module?
Also a 16 bit digital I/O module has many unused bits.

A way to handle this is to make the mask fields an array of octets.

The byte and bit order must still be decided but at least any multiple

of 8 bits can be handled.

I am astonished that we have this kind of discussion again. I may be

mistaken but I had the impression that it was agreed upon to use DA for

IOC internal acess to records and to abandon the efforts Marty started

to define internal implementation of epics types until we have got the

interfaces right. And that dbd definitions should be compiled into

C/C++ code implementing DA interfaces, views, etc.pp.

If indeed DA does not suffice as a (the) generic interface to record

fields, as Andrew suggested, then maybe DA should be extended or

revised accordingly?

Ben

At some point something other than interfaces has to be created!!

What Andrew and I are attempting is to define a small basic set of

standard types including strings and arrays that have built-in support.

For these types it should be easy to gererate code that implements

dataAccess interfaces to access the data.

Does anyone really want to have record support, device support, etc ALL

access data only via dataAccess?

That means everything will need to provide it's own set of code to use

dataAccess. I am again haunted by Doug's request for "hello world".

Marty

Experimental Physics and Industrial Control System

Experimental Physics and
Industrial Control System