STX and ETX escaping are optional now

src/fsfw/globalfunctions/DleEncoder.cpp

@@ -6,7 +6,7 @@ DleEncoder::~DleEncoder() {}
 
 ReturnValue_t DleEncoder::encode(const uint8_t* sourceStream,
 		size_t sourceLen, uint8_t* destStream, size_t maxDestLen,
-		size_t* encodedLen, bool addStxEtx) {
+		size_t* encodedLen, bool addStxEtx, bool escapeStxEtx, bool escapeCr) {
 	if (maxDestLen < 2) {
 		return STREAM_TOO_SHORT;
 	}
@@ -17,11 +17,12 @@ ReturnValue_t DleEncoder::encode(const uint8_t* sourceStream,
 		++encodedIndex;
 	}
 
-	while (encodedIndex < maxDestLen and sourceIndex < sourceLen)
+	while (encodedIndex < maxDestLen and sourceIndex < sourceLen) {
-	{
 		nextByte = sourceStream[sourceIndex];
 		// STX, ETX and CR characters in the stream need to be escaped with DLE
-		if (nextByte == STX_CHAR or nextByte == ETX_CHAR or nextByte == CARRIAGE_RETURN) {
+		if ((nextByte == STX_CHAR or nextByte == ETX_CHAR) or
+		        (escapeCr and nextByte == CARRIAGE_RETURN)) {
+		    if(escapeStxEtx) {
 	            if (encodedIndex + 1 >= maxDestLen) {
 	                return STREAM_TOO_SHORT;
 	            }
@@ -38,6 +39,7 @@ ReturnValue_t DleEncoder::encode(const uint8_t* sourceStream,
 	                destStream[encodedIndex] = nextByte + 0x40;
 	            }
 		    }
+		}
 		// DLE characters are simply escaped with DLE.
 		else if (nextByte == DLE_CHAR) {
 			if (encodedIndex + 1 >= maxDestLen) {
@@ -71,7 +73,7 @@ ReturnValue_t DleEncoder::encode(const uint8_t* sourceStream,
 
 ReturnValue_t DleEncoder::decode(const uint8_t *sourceStream,
 		size_t sourceStreamLen, size_t *readLen, uint8_t *destStream,
-		size_t maxDestStreamlen, size_t *decodedLen) {
+		size_t maxDestStreamlen, size_t *decodedLen, bool escapeStxEtx, bool escapeCr) {
 	size_t encodedIndex = 0, decodedIndex = 0;
 	uint8_t nextByte;
 	if (*sourceStream != STX_CHAR) {
@@ -90,17 +92,23 @@ ReturnValue_t DleEncoder::decode(const uint8_t *sourceStream,
 				destStream[decodedIndex] = nextByte;
 			}
 			else {
+			    if(escapeStxEtx) {
 	                /* The next byte is a STX, DTX or 0x0D character which
 	                 * was escaped by a DLE character. The actual byte was
 	                 * also encoded by adding + 0x40 to prevent having control chars,
 	                 * in the stream at all, so we convert it back. */
-				if (nextByte == 0x42 or nextByte == 0x43 or nextByte == 0x4D) {
+	                if ((nextByte == STX_CHAR + 0x40 or nextByte == ETX_CHAR + 0x40) or
+	                        (escapeCr and nextByte == CARRIAGE_RETURN + 0x40)) {
 	                    destStream[decodedIndex] = nextByte - 0x40;
 	                }
 	                else {
 	                    return DECODING_ERROR;
 	                }
 			    }
+			    else {
+	                return DECODING_ERROR;
+			    }
+			}
 			++encodedIndex;
 		}
 		else {

src/fsfw/globalfunctions/DleEncoder.h

@@ -13,9 +13,9 @@
  *
  * This encoder can be used to achieve a basic transport layer when using
  * char based transmission systems.
- * The passed source strean is converted into a encoded stream by adding
+ * The passed source stream is converted into a encoded stream by adding
  * a STX marker at the start of the stream and an ETX marker at the end of
- * the stream. Any STX, ETX, DLE and CR occurrences in the source stream are
+ * the stream. Any STX, ETX, DLE and CR occurrences in the source stream can be
  * escaped by a DLE character. The encoder also replaces escaped control chars
  * by another char, so STX, ETX and CR should not appear anywhere in the actual
  * encoded data stream.
@@ -45,21 +45,28 @@ public:
 
     /**
      * Encodes the give data stream by preceding it with the STX marker
-     * and ending it with an ETX marker. STX, ETX and DLE characters inside
+     * and ending it with an ETX marker. DLE characters inside
-     * the stream are escaped by DLE characters and also replaced by adding
+     * the stream are escaped by DLE characters. STX, ETX and CR characters can be escaped with a
-     * 0x40 (which is reverted in the decoding process).
+     * DLE character as well. The escaped characters are also encoded by adding
+     * 0x40 (which is reverted in the decoding process). This is performed so the source stream
+     * does not have STX/ETX/CR occurrences anymore, so the receiving side can simply parse for
+     * start and end markers
      * @param sourceStream
      * @param sourceLen
      * @param destStream
      * @param maxDestLen
      * @param encodedLen
-     * @param addStxEtx
+     * @param addStxEtx     Adding STX start marker and ETX end marker can be omitted,
-     * Adding STX and ETX can be omitted, if they are added manually.
+     *                      if they are added manually
+     * @param escapeStxEtx  STX and ETX occurrences in the given source stream will be escaped and
+     *                      encoded by adding 0x40
+     * @param escapeCr      CR characters in the given source stream will be escaped and encoded
+     *                      by adding 0x40
      * @return
      */
     static ReturnValue_t encode(const uint8_t *sourceStream, size_t sourceLen,
             uint8_t *destStream, size_t maxDestLen, size_t *encodedLen,
-            bool addStxEtx = true);
+            bool addStxEtx = true, bool escapeStxEtx = true, bool escapeCr = false);
 
     /**
      * Converts an encoded stream back.
@@ -69,11 +76,16 @@ public:
      * @param destStream
      * @param maxDestStreamlen
      * @param decodedLen
+     * @param escapeStxEtx  STX and ETX characters were escaped in the encoded stream and need to
+     *                      be decoded back as well
+     * @param escapeCr      CR characters were escaped in the encoded stream and need to
+     *                      be decoded back as well by subtracting 0x40
      * @return
      */
 	static ReturnValue_t decode(const uint8_t *sourceStream,
 			size_t sourceStreamLen, size_t *readLen, uint8_t *destStream,
-			size_t maxDestStreamlen, size_t *decodedLen);
+			size_t maxDestStreamlen, size_t *decodedLen, bool escapeStxEtx = true,
+			bool escapeCr = false);
 };
 
 #endif /* FRAMEWORK_GLOBALFUNCTIONS_DLEENCODER_H_ */

tests/src/fsfw_tests/internal/osal/CMakeLists.txt

@@ -1,5 +1,5 @@
 target_sources(${LIB_FSFW_NAME} PRIVATE
 	testMq.cpp
 	testMutex.cpp
-	TestSemaphore.cpp
+	testSemaphore.cpp
 )