fsfw/src/fsfw/globalfunctions/DleParser.h

125 lines
3.8 KiB
C
Raw Normal View History

2022-06-20 11:04:06 +02:00
#pragma once
2022-04-13 14:45:36 +02:00
#include <fsfw/container/SimpleRingBuffer.h>
#include <fsfw/globalfunctions/DleEncoder.h>
#include <fsfw/returnvalues/HasReturnvaluesIF.h>
#include <cstddef>
#include <utility>
/**
* @brief This base helper class can be used to extract DLE encoded packets from a data stream
* @details
* The core API of the parser takes received packets which can contains DLE packets. The parser
* can deal with DLE packets split across multiple packets. It does so by using a dedicated
* decoding ring buffer. The user can process received packets and detect errors by
* overriding two provided virtual methods. This also allows detecting multiple DLE packets
* inside one passed packet.
*/
class DleParser : public HasReturnvaluesIF {
public:
using BufPair = std::pair<uint8_t*, size_t>;
enum class ContextType { PACKET_FOUND, ERROR };
enum class ErrorTypes {
NONE,
ENCODED_BUF_TOO_SMALL,
DECODING_BUF_TOO_SMALL,
DECODE_ERROR,
RING_BUF_ERROR,
CONSECUTIVE_STX_CHARS,
CONSECUTIVE_ETX_CHARS
};
union ErrorInfo {
size_t len;
ReturnValue_t res;
};
using ErrorPair = std::pair<ErrorTypes, ErrorInfo>;
struct Context {
public:
Context(void* args) : userArgs(args) { setType(ContextType::PACKET_FOUND); }
void setType(ContextType type) {
if (type == ContextType::PACKET_FOUND) {
error.first = ErrorTypes::NONE;
error.second.len = 0;
} else {
decodedPacket.first = nullptr;
decodedPacket.second = 0;
}
}
ContextType getType() const { return type; }
BufPair decodedPacket = {};
ErrorPair error;
void* userArgs;
private:
ContextType type;
};
using UserHandler = void (*)(const Context& ctx);
/**
* Base class constructor
* @param decodeRingBuf Ring buffer used to store multiple packets to allow detecting DLE packets
* split across multiple packets
* @param decoder Decoder instance
* @param encodedBuf Buffer used to store encoded packets. It has to be large enough to hold
* the largest expected encoded DLE packet size
* @param decodedBuf Buffer used to store decoded packets. It has to be large enough to hold the
* largest expected decoded DLE packet size
* @param handler Function which will be called on a found packet
* @param args Arbitrary user argument
*/
DleParser(SimpleRingBuffer& decodeRingBuf, DleEncoder& decoder, BufPair encodedBuf,
BufPair decodedBuf, UserHandler handler, void* args);
/**
* This function allows to pass new data into the parser. It then scans for DLE packets
* automatically and inserts (part of) the packet into a ring buffer if necessary.
* @param data
* @param len
* @return
*/
ReturnValue_t passData(uint8_t* data, size_t len);
/**
* Example found packet handler
* function call
* @param packet Decoded packet
* @param len Length of detected packet
*/
void defaultFoundPacketHandler(uint8_t* packet, size_t len, void* args);
/**
* Will be called if an error occured in the #passData call
* @param err
* @param ctx Context information depending on the error type
* - For buffer length errors, will be set to the detected packet length which is too large
* - For decode or ring buffer errors, will be set to the result returned from the failed call
*/
static void defaultErrorHandler(ErrorTypes err, ErrorInfo ctx);
static void errorPrinter(const char* str, const char* opt = nullptr);
void prepareErrorContext(ErrorTypes err, ErrorInfo ctx);
/**
* Resets the parser by resetting the internal states and clearing the decoding ring buffer
*/
void reset();
private:
SimpleRingBuffer& decodeRingBuf;
DleEncoder& decoder;
BufPair encodedBuf;
BufPair decodedBuf;
UserHandler handler = nullptr;
Context ctx;
bool startFound = false;
};