Improvement : minor improvements to reduce number of allocations in R…

…PDOs, changed TPDOs to have same behavior

Only mapped length is considered for slicing and not the actual read/written length, otherwise this can offset

pkg/pdo/rpdo.go

@@ -72,6 +72,8 @@ func (rpdo *RPDO) Process(timeDifferenceUs uint32, timerNext *uint32, nmtIsOpera
 	rpdo.mu.Lock()
 	defer rpdo.mu.Unlock()
 
+	var buffer = make([]byte, 0, MaxPdoLength)
+
 	pdo := rpdo.pdo
 	if !pdo.Valid || !nmtIsOperational || (!syncWas && rpdo.synchronous) {
 		// not valid and op, clear can receive flags & timeouttimer
@@ -103,9 +105,11 @@ func (rpdo *RPDO) Process(timeDifferenceUs uint32, timerNext *uint32, nmtIsOpera
 	}
 	// Copy RPDO into OD variables
 	rpdoReceived := false
+	totalNbWritten := uint32(0)
+
 	for rpdo.rxNew[bufNo] {
 		rpdoReceived = true
-		dataRPDO := rpdo.rxData[bufNo][:]
+		dataRPDO := rpdo.rxData[bufNo]
 		rpdo.rxNew[bufNo] = false
 		for i := range pdo.nbMapped {
 			streamer := &pdo.streamers[i]
@@ -114,20 +118,17 @@ func (rpdo *RPDO) Process(timeDifferenceUs uint32, timerNext *uint32, nmtIsOpera
 			if dataLength > uint32(MaxPdoLength) {
 				dataLength = uint32(MaxPdoLength)
 			}
-			// Prepare for writing into OD
-			var buffer []byte
-			buffer, dataRPDO = dataRPDO[:mappedLength], dataRPDO[mappedLength:]
+			buffer = dataRPDO[totalNbWritten : totalNbWritten+mappedLength]
 			if dataLength > uint32(mappedLength) {
-				// Append zeroes up to 8 bytes
-				buffer = append(buffer, make([]byte, int(MaxPdoLength)-len(buffer))...)
+				buffer = buffer[:cap(buffer)]
 			}
 			streamer.DataOffset = 0
 			_, err := streamer.Write(buffer)
 			if err != nil {
 				log.Warnf("[RPDO][%x] failed to write to OD on RPDO reception because %v", rpdo.pdo.configuredId, err)
 			}
 			streamer.DataOffset = mappedLength
-
+			totalNbWritten += mappedLength
 		}
 	}
 	if rpdo.timeoutTimeUs <= 0 {

pkg/pdo/tpdo.go

@@ -184,12 +184,10 @@ func (tpdo *TPDO) send() error {
 	pdo := tpdo.pdo
 	eventDriven := tpdo.transmissionType == TransmissionTypeSyncAcyclic || tpdo.transmissionType >= uint8(TransmissionTypeSyncEventLo)
 
-	nbRead := 0
 	totalNbRead := 0
 	var err error
 
 	for i := range pdo.nbMapped {
-		totalNbRead += nbRead
 		streamer := &pdo.streamers[i]
 		mappedLength := streamer.DataOffset
 		dataLength := int(streamer.DataLength)
@@ -198,7 +196,7 @@ func (tpdo *TPDO) send() error {
 		}
 
 		streamer.DataOffset = 0
-		nbRead, err = streamer.Read(tpdo.txBuffer.Data[totalNbRead:])
+		_, err = streamer.Read(tpdo.txBuffer.Data[totalNbRead:])
 		if err != nil {
 			log.Warnf("[TPDO]sending TPDO cob id %x failed : %v", pdo.configuredId, err)
 			return err
@@ -209,6 +207,7 @@ func (tpdo *TPDO) send() error {
 		if flagPDOByte != nil && eventDriven {
 			*flagPDOByte |= pdo.flagPDOBitmask[i]
 		}
+		totalNbRead += int(mappedLength)
 	}
 	tpdo.sendRequest = false
 	tpdo.eventTimer = tpdo.eventTimeUs