fix STR bugs and improve code

- Reset reply size after returning a reply
- Reset data link layer and flush RX for regular commands and before
  performing special commands to ensure consistent start state
- Clean up DHB a bit
- Set STR dev to OFF in assembly when it is faulty.

linux/acs/StrComHandler.cpp

@@ -42,7 +42,6 @@ ReturnValue_t StrComHandler::performOperation(uint8_t operationCode) {
   while (true) {
     lock->lockMutex();
     state = InternalState::SLEEPING;
-    datalinkLayer.reset();
     lock->unlockMutex();
     semaphore.acquire();
     switch (state) {
@@ -58,6 +57,7 @@ ReturnValue_t StrComHandler::performOperation(uint8_t operationCode) {
       }
       case InternalState::UPLOAD_IMAGE: {
         replyTimeout.setTimeout(200);
+        resetReplyHandlingState();
         result = performImageUpload();
         if (result == returnvalue::OK) {
           triggerEvent(IMAGE_UPLOAD_SUCCESSFUL);
@@ -68,6 +68,7 @@ ReturnValue_t StrComHandler::performOperation(uint8_t operationCode) {
       }
       case InternalState::DOWNLOAD_IMAGE: {
         replyTimeout.setTimeout(200);
+        resetReplyHandlingState();
         result = performImageDownload();
         if (result == returnvalue::OK) {
           triggerEvent(IMAGE_DOWNLOAD_SUCCESSFUL);
@@ -78,6 +79,7 @@ ReturnValue_t StrComHandler::performOperation(uint8_t operationCode) {
       }
       case InternalState::FLASH_READ: {
         replyTimeout.setTimeout(200);
+        resetReplyHandlingState();
         result = performFlashRead();
         if (result == returnvalue::OK) {
           triggerEvent(FLASH_READ_SUCCESSFUL);
@@ -88,6 +90,7 @@ ReturnValue_t StrComHandler::performOperation(uint8_t operationCode) {
       }
       case InternalState::FIRMWARE_UPDATE: {
         replyTimeout.setTimeout(200);
+        resetReplyHandlingState();
         result = performFirmwareUpdate();
         if (result == returnvalue::OK) {
           triggerEvent(FIRMWARE_UPDATE_SUCCESSFUL);
@@ -645,7 +648,8 @@ ReturnValue_t StrComHandler::sendMessage(CookieIF* cookie, const uint8_t* sendDa
       return BUSY;
     }
   }
-  serial::flushRxBuf(serialPort);
+  // Ensure consistent state.
+  resetReplyHandlingState();
 
   const uint8_t* txFrame;
   size_t frameLen;
@@ -697,6 +701,7 @@ ReturnValue_t StrComHandler::readReceivedMessage(CookieIF* cookie, uint8_t** buf
     *buffer = const_cast<uint8_t*>(replyPtr);
     *size = replyLen;
   }
+  replyLen = 0;
   return replyResult;
 }
 
@@ -781,3 +786,8 @@ ReturnValue_t StrComHandler::readOneReply(uint32_t failParameter) {
     }
   }
 }
+
+void StrComHandler::resetReplyHandlingState() {
+  serial::flushRxBuf(serialPort);
+  datalinkLayer.reset();
+}