Basic Acquisition

The way to set a basic acquisition receive application is as follows:

• A receive channel must be obtained using the mxfModuleChannelGet() function or with the mxfModuleChannelAllGet() function by specifying the MXF_SCLASS_RXACQ_SRV subclass.
• The acquisition buffer must be allocated using the mxfRxAcqBufferAlloc() function.
• The acquisition mode can be set using the mxfRxAcqModeSet() function.
  
  Two modes of acquisition are defined:
  
  

  Condition	Description
  MXF_RXACQ_MODE_LINEAR	In this mode the acquisition stops when the buffer is full.
  MXF_RXACQ_MODE_CIRCULAR	In this mode the acquisition buffer is circular and never stops receiving. Whenever the acquisition queue becomes full, the acquisition process will discard the newest received record.

• The acquisition must be started using the mxfRxAcqStart() function.
• A read loop can be implemented using the mxfHDLCRxAcqRead() function. The mxfHDLCNextDataRecordPtrGet() function needs to be used to navigate in the receive buffer.

The MXF_HDLC_DATAREC structure must be used for reading a HDLC messages with acquisition service.

Example

The example below shows how to implement a HDLC basic receive acquisition application.

hdlc.c

HMXF_CHANNEL rxChannel;
HMXF_BUFFER rxBuffer;
size_t rxBufferSize=0;
MXF_HDLC_DATAREC *rxHostBuffer=NULL;
uint64 rxAcqStatus, msgCount, byteCount;
uint32 rc;

  ...

   // Allocates 4 KB buffer for RX data
   if(!rc)
   {
      rxBufferSize = 4*1024;

      // Allocates RX acquisition static buffer
      rc=mxfRxAcqBufferAlloc(rxChannel, rxBufferSize, &rxBuffer, NULL);

      // Host buffer allocation
      if(!rc)
      {
         rxHostBuffer = (MXF_HDLC_DATAREC*) calloc(1, rxBufferSize);
         if(!rxHostBuffer)
            rc = MAXT_ERROR_MEM;
      }
   }

   // Starts the acquisition process
   if (!rc)
      rc = mxfRxAcqStart(rxBuffer, MXF_RXACQ_FLAG_DEFAULT, 0, 0);

   ...

   if(!rc)
   {
      printf("Receiving ...\n");
      // Reads rx buffer
      rc = mxfHDLCRxAcqRead(rxBuffer, 0, rxBufferSize, &rxAcqStatus, &msgCount, &byteCount, rxHostBuffer);
   }

   if(!rc)
      printf("String received count = %llu \n", msgCount);

   if(!rc)
   {
   uint64 iRec,
          iData;
   MXF_HDLC_DATAREC *p=rxHostBuffer;

      // Displays received strings
      printf("\n");
      for(iRec=0; iRec < msgCount; iRec++)
      {
         printf("%03llu %010llu 0x%08x %02u ",  iRec, p->timeTag, p->control, p->dataSize);
         for(iData=0; iData < p->dataSize/2; iData++)
         {
            printf("%04x ", p->data[iData]);

            if(!((iData+1)%8) && (iData+1 < p->dataSize/2))
               printf("\n                              ");
         }

         printf("\n");

         mxfHDLCNextDataRecordPtrGet(p, &p);
      }
   }

   // Stops acquisition
   if(!rc)
      rc = mxfRxAcqStop(rxBuffer);

   ...