fsfw/globalfunctions/DleEncoder.h

72 lines
2.5 KiB
C++

#ifndef FRAMEWORK_GLOBALFUNCTIONS_DLEENCODER_H_
#define FRAMEWORK_GLOBALFUNCTIONS_DLEENCODER_H_
#include <framework/returnvalues/HasReturnvaluesIF.h>
#include <cstddef>
/**
* @brief This DLE Encoder (Data Link Encoder) can be used to encode and
* decode arbitrary data with ASCII control characters
* @details
* List of control codes:
* 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 strean is converted into a encoded stream by adding
* a STX marker at the startr of the stream and an ETX marker at the end of
* the stream. Any STX, ETX and DLE occurences in the source stream are escaped
* by a DLE character.
*/
class DleEncoder: public HasReturnvaluesIF {
private:
DleEncoder();
virtual ~DleEncoder();
public:
static constexpr uint8_t INTERFACE_ID = CLASS_ID::DLE_ENCODER;
static constexpr ReturnValue_t STREAM_TOO_SHORT = MAKE_RETURN_CODE(0x01);
static constexpr ReturnValue_t DECODING_ERROR = MAKE_RETURN_CODE(0x02);
//! Start Of Text character. First character is encoded stream
static const uint8_t STX = 0x02;
//! End Of Text character. Last character in encoded stream
static const uint8_t ETX = 0x03;
//! Data Link Escape character. Used to escape STX, ETX and DLE occurences
//! in the source stream.
static const uint8_t DLE = 0x10;
/**
* 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
* the stream are escaped by DLE characters.
* @param sourceStream
* @param sourceLen
* @param destStream
* @param maxDestLen
* @param encodedLen
* @param addStxEtx
* Adding STX and ETX can be omitted, if they are added manually.
* @return
*/
static ReturnValue_t encode(const uint8_t *sourceStream, size_t sourceLen,
uint8_t *destStream, size_t maxDestLen, size_t *encodedLen,
bool addStxEtx = true);
/**
* Converts an encoded stream back
* @param sourceStream
* @param sourceStreamLen
* @param readLen
* @param destStream
* @param maxDestStreamlen
* @param decodedLen
* @return
*/
static ReturnValue_t decode(const uint8_t *sourceStream,
size_t sourceStreamLen, size_t *readLen, uint8_t *destStream,
size_t maxDestStreamlen, size_t *decodedLen);
};
#endif /* FRAMEWORK_GLOBALFUNCTIONS_DLEENCODER_H_ */