diff --git a/src/fsfw/globalfunctions/DleEncoder.h b/src/fsfw/globalfunctions/DleEncoder.h index fab0e502..cc7dbc22 100644 --- a/src/fsfw/globalfunctions/DleEncoder.h +++ b/src/fsfw/globalfunctions/DleEncoder.h @@ -12,24 +12,29 @@ * https://en.wikipedia.org/wiki/C0_and_C1_control_codes * * This encoder can be used to achieve a basic transport layer when using - * char based transmission systems. - * 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 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. + * char based transmission systems. There are two implemented variants: * - * When using a strictly char based reception of packets encoded with DLE, + * 1. Escaped variant + * + * The encoded stream starts with a STX marker and ends with an ETX marker. + * STX and ETX occurrences in the stream are escaped and internally encoded as well so the + * receiver side can simply check for STX and ETX markers as frame delimiters. When using a + * strictly char based reception of packets encoded with DLE, * STX can be used to notify a reader that actual data will start to arrive * while ETX can be used to notify the reader that the data has ended. + * + * 2. Non-escaped variant + * + * The encoded stream starts with DLE STX and ends with DLE ETX. All DLE occurrences in the stream + * are escaped with DLE. If the received detects a DLE char, it needs to read the next char + * and to determine whether a start (STX) or end (ETX) of a frame has been detected. */ class DleEncoder: public HasReturnvaluesIF { public: /** * Create an encoder instance with the given configuration. - * @param escapeStxEtx - * @param escapeCr + * @param escapeStxEtx Determines whether the algorithm works in escaped or non-escaped mode + * @param escapeCr In escaped mode, escape all CR occurrences as well */ DleEncoder(bool escapeStxEtx = true, bool escapeCr = false); virtual ~DleEncoder(); @@ -62,10 +67,6 @@ public: * @param encodedLen * @param addStxEtx Adding STX start marker and ETX end marker can be omitted, * 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 */ ReturnValue_t encode(const uint8_t *sourceStream, size_t sourceLen, @@ -80,10 +81,6 @@ 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 */ ReturnValue_t decode(const uint8_t *sourceStream,