chEvtWaitOne in NIL?

[awygle]

Hi all,

RT events have three straightforward ways to wait for events - EvtWaitAny, EvtWaitAll, and EvtWaitOne. NIL events have only EvtWaitAny. In looking at the code it seems very easy to add support for WaitOne and WaitAll - is there a reason to leave these out from NIL?

I understand RT events are much more powerful with Event Sources and Listeners enabling many-to-many relationships, and this is not appropriate for NIL, but processing events one at a time in a loop seems to still be simple and useful.

My implementation of chEvtWaitOneTimeout is below - it requires only one more line compared to chEvtWaitAnyTimeout.

Thank you

Code: Select all

eventmask_t chEvtWaitOneTimeout(eventmask_t mask, systime_t timeout) {
  thread_t *ctp = nil.current;
  eventmask_t m;

  chSysLock();
  if ((m = (ctp->epmask & mask)) == (eventmask_t)0) {
    if (TIME_IMMEDIATE == timeout) {
      chSysUnlock();

      return (eventmask_t)0;
    }
    ctp->u1.ewmask = mask;
    if (chSchGoSleepTimeoutS(NIL_STATE_WTOREVT, timeout) < MSG_OK) {
      chSysUnlock();

      return (eventmask_t)0;
    }
    m = ctp->epmask & mask;
  }
  m ^= m & (m - (evtmask_t)1);
  ctp->epmask &= ~m;
  chSysUnlock();

  return m;
}

[Giovanni]

Hi,

I will look into adding those, I am concerned about features creep, NIL is meant to be small.

Giovanni

[awygle]

Thanks Giovanni,

I also noticed that there used to be chEvtWaitAnyTimeoutS in NIL but it got removed during the RT4/NIL2 merge - is this because RT did not have such a function? I found it useful when I needed to wait on either a mailbox message or an event - I could raise an event and send a message atomically with chEvtSignalI and chMBPostS, and then receive the message and clear the event atomically with chMBFetchS and chEvtWaitAnyTimeoutS.