crc.cpp

#include <iostream>
#include <string.h>
#include <regex>
#include <time.h>

using namespace std;
string xor1(string a, string b)
{
	string result = "";
	int n = b.length();
	for (int i = 1; i < n; i++)
	{
		if (a[i] == b[i])
			result += "0";
		else
			result += "1";
	}
	return result;
}
string mod2div(string divident, string divisor)
{
	int pick = divisor.length();
	string tmp = divident.substr(0, pick);
	int n = divident.length();
	while (pick < n)
	{
		if (tmp[0] == '1')
			tmp = xor1(divisor, tmp) + divident[pick];
		else
			tmp = xor1(string(pick, '0'), tmp) + divident[pick];
		pick += 1;
	}
	if (tmp[0] == '1')
		tmp = xor1(divisor, tmp);
	else
		tmp = xor1(string(pick, '0'), tmp);
	return tmp;
}
string sender(string data, string key)
{
	int l_key = key.length();
	string appended_data = (data + string(l_key - 1, '0'));
	string remainder = mod2div(appended_data, key);
	string codeword = data + remainder;
	cout << "Remainder (CRC): "
		 << remainder << "\n";
	cout << "Sent Data (Data + CRC) :"
		 << codeword << "\n";
	return (codeword);
}

void receiver(string data, string key)
{
	cout << "Received Data: " 
	     << data << endl;
	string crc = mod2div(data, key);

	if (regex_replace(crc, regex("0"), "").length() == 0)
		cout << "No Error";
	else
		cout << "Error";
}
int main()
{
	srand(time(0));

	string bin, key;
	int choice;
	cout << "Enter binary number\n";
	bin = "100100";
	// cin >> bin;
	cout << "Enter binary key\n";
	key = "1101";
	// cin >> key;
	string encodedData = sender(bin, key);

	if (rand() % 10 > 7)
	{
		int errorIndex = rand() % encodedData.length();
		encodedData[errorIndex] = encodedData[errorIndex] == '0' ? '1' : '0';
	}

	receiver(encodedData, key);

	return 0;
}

dijkstra.cpp

#include<iostream>
#include<climits>
using namespace std;

int miniDist(int distance[], bool Tset[])
{
    int minimum=INT_MAX,ind;

    for(int k=0;k<6;k++)
    {
        if(Tset[k]==false && distance[k]<=minimum)
        {
            minimum=distance[k];
            ind=k;
        }
    }
    return ind;
}

void DijkstraAlgo(int graph[6][6],int src)
{
    int distance[6];
    bool Tset[6];

    for(int k = 0; k<6; k++)
    {
        distance[k] = INT_MAX;
        Tset[k] = false;
    }

    distance[src] = 0;

    for(int k = 0; k<6; k++)
    {
        int m=miniDist(distance,Tset);
        Tset[m]=true;
        for(int k = 0; k<6; k++)
        {
            if(!Tset[k] && graph[m][k] && distance[m]!=INT_MAX && distance[m]+graph[m][k]<distance[k])
                distance[k]=distance[m]+graph[m][k];
        }
    }
    cout<<"Vertex\t\tDistance from source vertex"<<endl;
    for(int k = 0; k<6; k++)
    {
        char str=65+k;
        cout<<str<<"\t\t\t"<<distance[k]<<endl;
    }
}

int main()
{
    int graph[6][6]={
        {0, 1, 2, 0, 0, 0},
        {1, 0, 0, 5, 1, 0},
        {2, 0, 0, 2, 3, 0},
        {0, 5, 2, 0, 2, 2},
        {0, 1, 3, 2, 0, 1},
        {0, 0, 0, 2, 1, 0}};
    DijkstraAlgo(graph,0);
    return 0;
}

go_back_n_saw.cpp

// Go Back N
// Stop and Wait if window size is 1


#include <math.h>
#include <time.h>

#include <cstdlib>
#include <iostream>
using namespace std;

static int r = 0;
void sender(int);
bool receiver(int, int);

bool success(int success = 80) {
    return rand() % 100 < success;
}

void sender(int n, int w = 1) {
    int rec = 0, i = 1, init = 0;
    int bit, seq = (pow(2, w - 1) + 1);
    while (i <= n) {
        init = i;

        cout << "\n Frames Sent : " << w << " | ";
        for (int j = 0; j < w && j <= n - init; j++)
            cout << i + j << " ";

        for (int j = 0; j < w && j <= n - init; j++) {
            bit = (i - 1) % seq;
            cout << "\n Frame " << i << " | ";
            rec = receiver(bit, seq);
            if (rec) {
                cout << "Received";
                i += 1;
            } else {
                cout << "Timeout ";
                break;
            }
        }

        cout << "\n Frames Received | ";
        while (init < i) {
            cout << init << " ";
            init += 1;
        }
        cout << endl;
    }
}

bool receiver(int fbit, int seq) {
    if (success()) {
        if (r == fbit) {
            r = (r + 1) % seq;
        } else
            cout << "Duplicate ";
        return success(90);
    } else {
        cout << "Damaged ";
        return false;
    }
}

int main() {
    srand(time(NULL));
    int n = 0, w = 1;
    cout << " Enter The Number Of Frames : ";
    cin >> n;
    cout << " Enter The window size : ";
    cin >> w;
    sender(n, w);
    return 0;
}

selective_repeat.cpp

/*
 * 	Selective Repeat Slide
 *  Created on: 01-Nov-2014
 *      Author: Gourav Siddhad
 */

#include <time.h>

#include <cstdlib>
#include <iostream>
using namespace std;

static int done = 0;
void sender(int, int);
int receiver(int[], bool[], int);

bool success(int success = 80) {
    return rand() % 100 < success;
}

void sender(const int f, const int w) {
    int temp = 0;
    int frames[w + 1], win = 0;
    bool ack[w + 1], ackno[f + 1];

    for (int j = 0; j <= f; j++) ackno[j] = 0;

    for (int i = 0; i < f;) {
        win = 0, temp = i;
        for (int j = 0; j < f; j++) {
            if (win == w) break;
            if (ackno[j] == 0) {
                ack[win] = 0;
                frames[win] = j;
                win++;
            }
        }

        cout << "\n Frames Sent : " << win << " | ";
        for (int j = 0; j < win; j++)
            if (ack[j] == 0)
                cout << frames[j] + 1 << " ";
            else {
                if ((frames[j] + 1) % 100 > 10)
                    cout << " ";
                cout << "  ";
            }

        i = receiver(frames, ack, win);
        for (int j = 0; j < win; j++) {
            ackno[frames[j]] = ack[j];
        }

        if (i == temp)
            cout << "\n Time Out... Resending... ";
    }
}

int receiver(int frames[], bool ack[], int win) {
    for (int i = 0; i < win; i++) {
        ack[i] = success();
    }

    cout << "\n Frames Received ";
    if (win % 100 > 9)
        cout << " ";
    cout << "| ";

    for (int i = 0; i < win; i++)
        if (ack[i] == 1) {
            cout << frames[i] + 1 << " ";
            done++;
        } else {
            if ((frames[i] + 1) % 100 > 9)
                cout << " ";
            cout << "  ";
        }

    cout << endl;
    return done;
}

int main() {
    srand(time(NULL));
    int f, w;
    cout << " Enter The Number Of Frames : ";
    cin >> f;
    cout << " Enter Window Size : ";
    cin >> w;
    sender(f, w);
    return 0;
}