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several imporovements

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This commit is contained in:
Robin Müller 2021-08-17 16:00:39 +02:00
parent 28f2db2c11
commit 654b23869f
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GPG Key ID: 11D4952C8CCEF814
2 changed files with 34 additions and 33 deletions
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24
src/fsfw/globalfunctions/DleEncoder.cpp
View File

@ -83,7 +83,7 @@ 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 encodedIndex = 0, decodedIndex = 0;
size_t encodedIndex = 0;
if(not escapeStxEtx) {
if (*sourceStream != DLE_CHAR) {
return DECODING_ERROR;
@ -94,21 +94,22 @@ ReturnValue_t DleEncoder::decode(const uint8_t *sourceStream,
return DECODING_ERROR;
}
++encodedIndex;
if(escapeStxEtx) {
return decodeStreamEscaped(encodedIndex, decodedIndex, sourceStream, sourceStreamLen,
return decodeStreamEscaped(sourceStream, sourceStreamLen,
readLen, destStream, maxDestStreamlen, decodedLen);
}
else {
return decodeStreamNonEscaped(encodedIndex, decodedIndex, sourceStream, sourceStreamLen,
return decodeStreamNonEscaped(sourceStream, sourceStreamLen,
readLen, destStream, maxDestStreamlen, decodedLen);
}
}
ReturnValue_t DleEncoder::decodeStreamEscaped(size_t encodedIndex, size_t decodedIndex,
const uint8_t *sourceStream, size_t sourceStreamLen, size_t *readLen, uint8_t *destStream,
ReturnValue_t DleEncoder::decodeStreamEscaped(const uint8_t *sourceStream, size_t sourceStreamLen,
size_t *readLen, uint8_t *destStream,
size_t maxDestStreamlen, size_t *decodedLen) {
// Skip start marker, was already checked
size_t encodedIndex = 1;
size_t decodedIndex = 0;
uint8_t nextByte;
while ((encodedIndex < sourceStreamLen) && (decodedIndex < maxDestStreamlen)
&& (sourceStream[encodedIndex] != ETX_CHAR)
@ -158,9 +159,12 @@ ReturnValue_t DleEncoder::decodeStreamEscaped(size_t encodedIndex, size_t decode
}
}
ReturnValue_t DleEncoder::decodeStreamNonEscaped(size_t encodedIndex, size_t decodedIndex,
const uint8_t *sourceStream, size_t sourceStreamLen, size_t *readLen, uint8_t *destStream,
ReturnValue_t DleEncoder::decodeStreamNonEscaped(const uint8_t *sourceStream,
size_t sourceStreamLen, size_t *readLen, uint8_t *destStream,
size_t maxDestStreamlen, size_t *decodedLen) {
// Skip start marker, was already checked
size_t encodedIndex = 2;
size_t decodedIndex = 0;
uint8_t nextByte;
while ((encodedIndex < sourceStreamLen) && (decodedIndex < maxDestStreamlen)) {
if (sourceStream[encodedIndex] == DLE_CHAR) {
@ -177,6 +181,8 @@ ReturnValue_t DleEncoder::decodeStreamNonEscaped(size_t encodedIndex, size_t dec
}
else if(nextByte == ETX_CHAR) {
// End of stream reached
*readLen = encodedIndex + 2;
*decodedLen = decodedIndex;
return RETURN_OK;
}
}

43
src/fsfw/globalfunctions/DleEncoder.h
View File

@ -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,
@ -80,23 +81,17 @@ 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,
size_t sourceStreamLen, size_t *readLen, uint8_t *destStream,
size_t maxDestStreamlen, size_t *decodedLen);
ReturnValue_t decodeStreamEscaped(size_t encodedIndex, size_t decodedIndex,
const uint8_t *sourceStream, size_t sourceStreamLen, size_t *readLen,
uint8_t *destStream, size_t maxDestStreamlen, size_t *decodedLen);
ReturnValue_t decodeStreamEscaped(const uint8_t *sourceStream, size_t sourceStreamLen,
size_t *readLen, uint8_t *destStream, size_t maxDestStreamlen, size_t *decodedLen);
ReturnValue_t decodeStreamNonEscaped(size_t encodedIndex, size_t decodedIndex,
const uint8_t *sourceStream, size_t sourceStreamLen, size_t *readLen,
uint8_t *destStream, size_t maxDestStreamlen, size_t *decodedLen);
ReturnValue_t decodeStreamNonEscaped(const uint8_t *sourceStream, size_t sourceStreamLen,
size_t *readLen, uint8_t *destStream, size_t maxDestStreamlen, size_t *decodedLen);
private: