Question-1.cc

#include <iostream>
#include <fstream>
#include <string>

// Question 1: This is an extension task that requires you to decode sensor data from a CAN log file.
// CAN (Controller Area Network) is a communication standard used in automotive applications (including Redback cars)
// to allow communication between sensors and controllers.
//
// Your Task: Using the definition in the Sensors.dbc file, extract the "WheelSpeedRR" values
// from the candump.log file. Parse these values correctly and store them in an output.txt file with the following format:
// (<UNIX_TIME>): <DECODED_VALUE>
// eg:
// (1705638753.913408): 1234.5
// (1705638754.915609): 6789.0
// ...
// The above values are not real numbers; they are only there to show the expected data output format.
// You do not need to use any external libraries. Use the resources below to understand how to extract sensor data.
// Hint: Think about manual bit masking and shifting, data types required,
// what formats are used to represent values, etc.
// Resources:
// https://www.csselectronics.com/pages/can-bus-simple-intro-tutorial
// https://www.csselectronics.com/pages/can-dbc-file-database-intro

int main() {
    // Setup files
    std::ifstream logFile("candump.log");
    std::ofstream outFile("output.txt");

    if (!logFile.is_open()) { std::cerr << "Cannot open candump.log\n"; return 1; }
    if (!outFile.is_open()) { std::cerr << "Cannot open wheelspeed_rr.txt\n"; return 1; }

    // Values from SensorBus.dbc
    const std::string TARGET_ID = "705";
    const double FACTOR = 0.1;

    // Parse lines from candump.log
    std::string line;
    while (std::getline(logFile, line)) {
        // Select ECU_WheelSpeed data only
        const size_t hashPos = line.find('#');
        if (line.substr(hashPos - 3, 3) != TARGET_ID) continue;

        // Extract timestamp
        std::string ts = line.substr(0, line.find(')') + 1);

        // Extract wheelspeed value
        uint64_t raw_data = std::stoull(line.substr(hashPos + 1), nullptr, 16);
        uint8_t rr_lsb = (raw_data >> 24) & 0xFF;
        uint8_t rr_msb = (raw_data >> 16) & 0xFF;
        int16_t signed_value = (static_cast<int16_t>(rr_msb) << 8) | rr_lsb;
        double wheelSpeedRR = signed_value * FACTOR;

        // Store values
        outFile << ts << ": " << wheelSpeedRR << "\n";
    }

    // Close files
    logFile.close();
    outFile.close();
    std::cout << "Values written to output.txt\n";
    return 0;
}