protocol.h

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#pragma once
#include <stdint.h>
#include "crc.h"
 
namespace modules {
 
 
namespace protocol {
 
enum class RequestMsgCodes : uint8_t {
    unknown = 0,
    Query = 'Q',
    Tool = 'T',
    Load = 'L',
    Mode = 'M',
    Unload = 'U',
    Reset = 'X',
    Finda = 'P',
    Version = 'S',
    Button = 'B',
    Eject = 'E',
    Write = 'W',
    Cut = 'K',
    FilamentType = 'F',
    FilamentSensor = 'f',
    Home = 'H',
    Read = 'R'
};
 
enum class ResponseMsgParamCodes : uint8_t {
    unknown = 0,
    Processing = 'P',
    Error = 'E',
    Finished = 'F',
    Accepted = 'A',
    Rejected = 'R',
    Button = 'B' // the MMU registered a button press and is sending it to the printer for processing
};
 
struct RequestMsg {
    RequestMsgCodes code; 
    uint8_t value; 
    uint16_t value2; 
 
    uint8_t crc8;
 
    constexpr uint8_t ComputeCRC8() const {
        uint8_t crc = 0;
        crc = modules::crc::CRC8::CCITT_updateCX(0, (uint8_t)code);
        crc = modules::crc::CRC8::CCITT_updateCX(crc, value);
        crc = modules::crc::CRC8::CCITT_updateW(crc, value2);
        return crc;
    }
 
    inline constexpr RequestMsg(RequestMsgCodes code, uint8_t value)
        : code(code)
        , value(value)
        , value2(0)
        , crc8(ComputeCRC8()) {
    }
 
    inline constexpr RequestMsg(RequestMsgCodes code, uint8_t address, uint16_t value)
        : code(code)
        , value(address)
        , value2(value)
        , crc8(ComputeCRC8()) {
    }
 
    constexpr uint8_t CRC() const { return crc8; }
};
 
struct ResponseMsg {
    RequestMsg request; 
    ResponseMsgParamCodes paramCode; 
    uint16_t paramValue; 
 
    constexpr uint8_t ComputeCRC8() const {
        uint8_t crc = request.ComputeCRC8();
        crc = modules::crc::CRC8::CCITT_updateCX(crc, (uint8_t)paramCode);
        crc = modules::crc::CRC8::CCITT_updateW(crc, paramValue);
        return crc;
    }
 
    inline constexpr ResponseMsg(RequestMsg request, ResponseMsgParamCodes paramCode, uint16_t paramValue)
        : request(request)
        , paramCode(paramCode)
        , paramValue(paramValue) {
        this->request.crc8 = ComputeCRC8();
    }
 
    constexpr uint8_t CRC() const { return request.crc8; }
};
 
struct ResponseCommandStatus {
    ResponseMsgParamCodes code;
    uint16_t value;
    inline constexpr ResponseCommandStatus(ResponseMsgParamCodes code, uint16_t value)
        : code(code)
        , value(value) {}
};
 
enum class DecodeStatus : uint_fast8_t {
    MessageCompleted, 
    NeedMoreData, 
    Error, 
};
 
class Protocol {
public:
    inline Protocol()
        : rqState(RequestStates::Code)
        , requestMsg(RequestMsgCodes::unknown, 0)
        , rspState(ResponseStates::RequestCode)
        , responseMsg(RequestMsg(RequestMsgCodes::unknown, 0), ResponseMsgParamCodes::unknown, 0) {
    }
 
    DecodeStatus DecodeRequest(uint8_t c);
 
    DecodeStatus DecodeResponse(uint8_t c);
 
    static uint8_t EncodeRequest(const RequestMsg &msg, uint8_t *txbuff);
 
    static uint8_t EncodeWriteRequest(uint8_t address, uint16_t value, uint8_t *txbuff);
 
    static constexpr uint8_t MaxRequestSize() { return 13; }
 
    static constexpr uint8_t MaxResponseSize() { return 14; }
 
    static uint8_t EncodeResponseCmdAR(const RequestMsg &msg, ResponseMsgParamCodes ar, uint8_t *txbuff);
 
    static uint8_t EncodeResponseReadFINDA(const RequestMsg &msg, uint8_t findaValue, uint8_t *txbuff);
 
    static uint8_t EncodeResponseQueryOperation(const RequestMsg &msg, ResponseCommandStatus rcs, uint8_t *txbuff);
 
    static uint8_t EncodeResponseRead(const RequestMsg &msg, bool accepted, uint16_t value2, uint8_t *txbuff);
 
    inline const RequestMsg GetRequestMsg() const { return requestMsg; }
 
    inline const ResponseMsg GetResponseMsg() const { return responseMsg; }
 
    void ResetRequestDecoder() {
        rqState = RequestStates::Code;
    }
 
    void ResetResponseDecoder() {
        rspState = ResponseStates::RequestCode;
    }
 
#ifndef UNITTEST
private:
#endif
    enum class RequestStates : uint8_t {
        Code, 
        Value, 
        Address, 
        WriteValue, 
        CRC, 
        Error 
    };
 
    RequestStates rqState;
    RequestMsg requestMsg;
 
    enum class ResponseStates : uint8_t {
        RequestCode, 
        RequestValue, 
        ParamCode, 
        ParamValue, 
        CRC, 
        Error 
    };
 
    ResponseStates rspState;
    ResponseMsg responseMsg;
 
    static constexpr bool IsNewLine(uint8_t c) {
        return c == '\n' || c == '\r';
    }
    static constexpr bool IsDigit(uint8_t c) {
        return c >= '0' && c <= '9';
    }
    static constexpr bool IsCRCSeparator(uint8_t c) {
        return c == '*';
    }
    static constexpr bool IsHexDigit(uint8_t c) {
        return (c >= '0' && c <= '9') || (c >= 'a' && c <= 'f');
    }
    static constexpr uint8_t Char2Nibble(uint8_t c) {
        switch (c) {
        case '0':
        case '1':
        case '2':
        case '3':
        case '4':
        case '5':
        case '6':
        case '7':
        case '8':
        case '9':
            return c - '0';
        case 'a':
        case 'b':
        case 'c':
        case 'd':
        case 'e':
        case 'f':
            return c - 'a' + 10;
        default:
            return 0;
        }
    }
 
    static constexpr uint8_t Nibble2Char(uint8_t n) {
        switch (n) {
        case 0:
        case 1:
        case 2:
        case 3:
        case 4:
        case 5:
        case 6:
        case 7:
        case 8:
        case 9:
            return n + '0';
        case 0xa:
        case 0xb:
        case 0xc:
        case 0xd:
        case 0xe:
        case 0xf:
            return n - 10 + 'a';
        default:
            return 0;
        }
    }
 
    static uint8_t UInt8ToHex(uint8_t value, uint8_t *dst);
 
    static uint8_t UInt16ToHex(uint16_t value, uint8_t *dst);
 
    static uint8_t BeginEncodeRequest(const RequestMsg &msg, uint8_t *dst);
 
    static uint8_t AppendCRC(uint8_t crc, uint8_t *dst);
};
 
} // namespace protocol
} // namespace modules
 
namespace mp = modules::protocol;