Experimental Physics and
Industrial Control System

Ben Franksen via Core-talk <core-talk at aps.anl.gov> · Wed, 18 Mar 2020 20:47:08 +0100

The way we distinguish between how much information is contained in a
db_field_log using its 'type' member looks a bit questionable to me.
What I observe is that the case distinctions are strewn all over the
place and in quite a repetitive manner. For instance, this sort of code:

    if (!pfl || pfl->type == dbfl_type_rec)
        field_type = paddr->field_type;
    else
        field_type = pfl->field_type;

can be found in many places in dbAccess.c. This should perhaps be
cleaned up using a hand full of macros(*).

Furthermore, the distinction is not consequently reflected in the data
structures. This comment is from db_field_log.h:

 * dbfl_type_rec - Reference to record
 *  The field log stores no data itself.  Data must instead be taken
 *  via the dbChannel* which must always be provided along
 *  with the field log.
 *  For this type only the 'type' and 'ctx' members are used.

This suggests a refactor:

(a) The meta data should be contained (as a sub-struct) in both struct
    dbfl_val and struct dbfl_ref and not as direct members of
    db_field_log.

(b) The "dbChannel* which must always be provided along with the field
    log" should be a member of the field log as a member of the union
    (possibly wrapped in a struct dbfl_rec).

I am thinking of making refactors along these lines before I further
embark on the planned additions.

(*) I assume that we still cannot use proper inline functions (as
defined in C99) in C code due to limitations in Microsoft's VS? I
googled a bit and it looks as if VS understands __inline, though it is
unclear what the exact semantics are.

Cheers
Ben

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Experimental Physics and Industrial Control System

Experimental Physics and
Industrial Control System