Experimental Physics and
Industrial Control System

Frank Lenkszus <[email protected]> · Thu, 20 Sep 2001 09:58:08 -0500 (CDT)

The 3.13 Record Reference manual pages for the SubArray record state that
the field MALM is the "Maximum Number of Elements in the Sub-array". This is
not true. If I wish to extract one element and only one element from a
waveform record, and therefore the "Maximum Number of Elements in the Sub-array"
is "1" the record support forces the INDX field to "0";i.e, I can never 
access any element greater than "0" From the record support code for  the
Sub-Array record:

        if (psa->indx >= psa->malm)
        {
           psa->indx = psa->malm - 1;
        }

The consequences of this is if one is required to blow out each and every
element of an array into a separate process variable (Don't ask why - it's
imposed on me by other considerations) MALM must be set to the input array size,
not the "Maximum Sub-Array Size" which in this case is "1".  Since the record
support allocates memory based on MALM, breaking up an N element array into N
process variables means NxN memory locations will be allocated, even though only
N elements will be used!  Not a problem for small arrays but when larger arrays
are involved the memory consumption seems excessive.

If this has been covered before, please excuse the noise.

Frank

Experimental Physics and Industrial Control System

Experimental Physics and
Industrial Control System