Asynchronous Events

An application can register condition(s) to be monitored by the receive firmware.

When a callback handler is defined, the condition(s) are reported to the application asynchronously from the firmware to the handler.

The way to define an handler is as follows:

• Initialize the receive acquisition as usual.
• A callback handler must be registered using the mxfAsyncEventHandlerInit() function.
• The conditions to monitor must be defined using the mxfAsyncEventConditionsSet() function.

After this registration, the application can read acquisition data as usual and/or received asynchronous events through the callback handler.

The receive queue can also be read from the callback handler if necessary.

List of conditions

The event conditions that can be monitored are as follows:

Condition	Description
MXF_ASYNCEVENT_COND_RXACQ_BUFFER_THRESHOLD	Acquisition buffer threshold exceeded.
MXF_ASYNCEVENT_COND_RX_ERROR	Receive errors on the RX port.

Example

In the example below a condition handler is defined for monitoring MXF_ASYNCEVENT_COND_RXACQ_BUFFER_THRESHOLD condition and ASYNC RX acquisition channel started for receiving data.

uint32 asyncEventHandler(HMXF_ASYNCEVENT asyncEvent, void *param)
{
MXF_ASYNCEVENT_PENDING_INFO pendingList[64];
HMXF_CHANNEL channel;
uint64 i, maxCount=64, pendingCount, status;
uint32 rc=MAXT_SUCCESS;
uint64 dev, mod, port;

   // Builds the list of pending events to process
   rc = mxfAsyncEventPendingGet(asyncEvent, maxCount, &pendingCount, pendingList);

   for (i=0; i < pendingCount && !rc; i++)
   {
      switch(pendingList[i].condID)
      {
      // The buffer is almost full, we should then read the data with mxfASYNCEHRxAcqRead().
         case MXF_ASYNCEVENT_COND_RXACQ_BUFFER_THRESHOLD:
         {
         char *rec;
         HMXF_BUFFER buffer;
         uint64 msgCount, byteCount;
         uint64 msg;
         uint32 rc=MAXT_SUCCESS;

           buffer = pendingList[i].condition.rxAcqBufferThreshold.buffer;

           rec = malloc(1024);
           if(rec)
           {
              // Reads the records
              rc = mxfASYNCEHRxAcqRead(buffer, 0, 1024, &status, &msgCount, &byteCount, (MXF_ASYNCEH_DATAREC *)rec);
              free(rec);
           }

           break;
      }

      // A receive error was detected
      case MXF_ASYNCEVENT_COND_RX_ERROR:
        channel = pendingList[i].condition.rxErr.channel;
        status = pendingList[i].condition.rxErr.status;
        rc = mxfChannelLocationGet(channel, &dev, &mod, &port);
        if(!rc)
           printf("Status 0x%08llx received on channel %llu.%llu.%llu\n", status, dev, mod, port);
        break;

      default:
        printf("Unknown condID 0x%llx)", pendingList[i].condID);
        break;
      }
  }     

  return rc;
}

int main()
{
HMXF_SERVER  server;
MXF_ASYNCEVENT_CONDITION asyncEventInfo[2];
HMXF_DEVICE  device=NULL;
HMXF_MODULE  module=NULL;
HMXF_CHANNEL channel=NULL;
HMXF_BUFFER  buffer=NULL;
HMXF_ASYNCEVENT asyncEvent=NULL;
uint64 count;
uint32 rc;

    // Connects to services and initialize environment
    rc = mxfServerConnect("0.0.0.0", "", "", FALSE, &server);

    // Initializes the server.
    if (!rc)
    {
        rc = mxfSystemInit(server);
        if (!rc)
        {
            // Gets the device handle.
            rc = mxfSystemDeviceAllGet(server, MXF_DEVICE_ALL, 1, &count, &device);
            if (!rc)
                rc = mxfDeviceModuleAllGet(device, MXF_MODULE_ASYNC_EH, 1, &count, &module);
        }
    }

    // Obtains the first ASYNC Protocol RX channel (RX logical #0).
    if (!rc)
        rc = mxfModuleChannelAllGet(module, MXF_CLASS_ASYNC_ENHANCED, MXF_SCLASS_RX_CHANNEL, 1, &count, &channel);

    if (!rc)
    // Allocates RX acquisition buffers
        rc = mxfRxAcqBufferAlloc(channel, 1024, &buffer, NULL);

    if (!rc)
    // Registers the callback handler service function
        rc = mxfAsyncEventHandlerInit(server, asyncEventHandler, NULL, &asyncEvent);

    memset(&asyncEventInfo, 0, sizeof(asyncEventInfo));

    // Acquisition threshold; the callback gets called when the receive FIFO is
    // almost full >=4 until it gets to < 1 word (almost empty).
    asyncEventInfo[0].condID = MXF_ASYNCEVENT_COND_RXACQ_BUFFER_THRESHOLD;
    asyncEventInfo[0].condition.rxAcqBufferThreshold.almostFull=4;
    asyncEventInfo[0].condition.rxAcqBufferThreshold.almostEmpty=1;
    asyncEventInfo[0].condition.rxAcqBufferThreshold.buffer=buffer;

    // Receive message in error; the callback gets called when a data word in error is detected
    asyncEventInfo[1].condID = MXF_ASYNCEVENT_COND_RX_ERROR;
    asyncEventInfo[1].condition.rxErr.channel = channel;

   // Enables Acquisition threshold interrupt
   if (!rc)
      rc = mxfAsyncEventConditionsSet(asyncEvent, TRUE, 2, asyncEventInfo);

  // Starts the acquisition process
  if (!rc)
        rc = mxfRxAcqModeSet(buffer, MXF_RXACQ_MODE_LINEAR);

   if (!rc)
        rc = mxfRxAcqStart(buffer, MXF_RXACQ_FLAG_DEFAULT, 0, 0);

    // At this point a transmission must be running
   if (!rc)
       mxfSleep(5000);

   if (buffer)
        mxfRxAcqStop(buffer);

   if (!rc)
      rc = mxfAsyncEventConditionsSet(asyncEvent, FALSE, 2, asyncEventInfo);

    // Checks for any errors
  if (rc)
      printf("Error code=0x%lX\n", rc);      

   if (asyncEvent)
      mxfAsyncEventHandlerTerminate(asyncEvent);

   if (device)
      mxfDeviceBuffersFree(device);

    mxfSystemTerminate(server);
    mxfServerDisconnect(server);
}