autosave: pass-0 and pass-1 with a custom device support

[Andrea Celentano via Tech-talk <tech-talk@aps.anl.gov>]

Dear colleagues,

I have an analog output record, with a custom device support. 

The record reads:

record(ao, "$(HOST):C0:IOB:set")
{
    field(DRVH, "31")
    field(DRVL, "0")
    field(DTYP, "WAVEBOARD_ZYNQ")
    field(FLNK, "$(HOST):C0:FanOut")
    field(OUT,  "@writeIOB_0")
    info(autosaveFields, "VAL")
}

The init_record function is reported below. I am not modifying here in any way the prec->val.

static long init_record_ao(void *arg) {
    aoRecord *prec = (aoRecord*) (arg);
    printf("init record_ao %s start (eventual value: %f)\n", prec->name,prec->val);
    std::string str;

    if (!AxiMM.GetInitialized()) {
        printf("AXI controller not initialized! Exiting...\n");
        return -1;
    }
    str = std::string(prec->out.value.constantStr);

    struct privRecordData *priv = new privRecordData;
    /*A.C. here we need to decode the string "str", that should be: COMMAND_CHANNEL - or just COMMAND*/
    priv->raw=str;
    getCommandChannel(str, priv->command, priv->channel);

    prec->dpvt = priv;
       
    return 0;
}

I am experimenting with the autosave module. The value to be retrieved is 13. 

If I set VAL to be retreived at pass-1 (AFTER record initialization), I see in the output:

init record_ao waveboard201:C0:IOB:set start (eventual value: 0.000000)

while if I set it at pass-0, I see:

init record_ao waveboard201:C0:IOB:set start (eventual value: 13.000000)

This is expected, and I understand this: pass-0 means before record initialization, hence the value is available to init_record_ao.

However, if I set VAL to be retrieved at pass-0, the value of this PV, at the end of record initialization, as obtained from caget is 0. I do not understand this - is it there a default initialization step occurring after my init_record_ao function is called, but before the instant at which pass-1 variables are retrieved?

Thanks,

Bests,

Andrea