ComputerNetworksAndSecurity/Codes/Code-A3 (Hamming Code).cpp

#include <iostream>
#include <cmath>
#include <vector>
using namespace std;

// Function to calculate the number of parity bits needed
int calculateParityBits(int dataBits) {
    int parityBits = 0;
    while (pow(2, parityBits) < dataBits + parityBits + 1) {
        parityBits++;
    }
    return parityBits;
}

// Function to encode the data using Hamming code
vector<int> encodeData(vector<int> data) {
    int dataBits = data.size();
    int parityBits = calculateParityBits(dataBits);
    vector<int> encoded(dataBits + parityBits, 0);

    // Set the data bits
    int j = 0;
    for (int i = 0; i < encoded.size(); i++) {
        if (i + 1 == pow(2, j)) {
            j++;
        } else {
            encoded[i] = data[i - j];
        }
    }

    // Calculate and set the parity bits
    for (int i = 0; i < parityBits; i++) {
        int parityBit = pow(2, i);
        int sum = 0;
        for (int j = parityBit - 1; j < encoded.size(); j += 2 * parityBit) {
            for (int k = 0; k < parityBit; k++) {
                if (j + k < encoded.size()) {
                    sum += encoded[j + k];
                }
            }
        }
        encoded[parityBit - 1] = sum % 2;
    }

    return encoded;
}

// Function to check for errors in the encoded data
int checkForErrors(vector<int> encoded) {
    int parityBits = calculateParityBits(encoded.size() - calculateParityBits(encoded.size()));
    int errorPosition = 0;

    for (int i = 0; i < parityBits; i++) {
        int parityBit = pow(2, i);
        int sum = 0;
        for (int j = parityBit - 1; j < encoded.size(); j += 2 * parityBit) {
            for (int k = 0; k < parityBit; k++) {
                if (j + k < encoded.size()) {
                    sum += encoded[j + k];
                }
            }
        }
        errorPosition += (sum % 2) * parityBit;
    }

    return errorPosition;
}

int main() {
    int dataBits;
    cout<<"Enter the number of data bits:\t";
    cin >> dataBits;

    vector<int> data(dataBits);
    cout<<endl<<"NOTE: Make sure the bits are entered in binary format, separated by spaces.\nEg. 1 0 0 1 (for 4 data bits).";
    cout<<endl<<"Enter the data bits:\t";
    for (int i = 0; i < dataBits; i++) {
        cin >> data[i];
    }

    vector<int> encoded = encodeData(data);
    cout<<endl<<"--------------------"<<endl;
    cout<<"Encoded bits are:\t";
    for (int bit : encoded) {
        cout << bit << " ";
    }
    cout<<endl<<"--------------------"<<endl;

    cout<<endl<<"Enter the encoded bits:\t";
    vector<int> receivedEncoded(encoded.size());
    for (int i = 0; i < encoded.size(); i++) {
        cin >> receivedEncoded[i];
    }

    int errorPosition = checkForErrors(receivedEncoded);
    if (errorPosition == 0) {
        cout<<"No errors detected."<<endl;
    } else {
        cout<<"Error detected at position: "<<errorPosition<<endl;
    }

    return 0;
}