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SubhangiSatiSubhangiSati
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‎Bit_stuffing.java

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package dcn_lab1;
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import java.io.FileWriter;
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import java.io.IOException;
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import java.lang.StringBuilder;
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import java.io.*;
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import java.util.*;
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public class Bit_stuffing {
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public static void main(String[] args) throws IOException {
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Scanner sc = new Scanner(System.in);
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System.out.println("YOUR FILE NAME~ File.txt ");
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//File Creation
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System.out.println("ENTER NAME OF YOUR FILE~ ");
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String filename=sc.nextLine();
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File name = new File(filename);
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boolean value = name.createNewFile();
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if(value) {
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System.out.println("FILE SUCCESSFULLY CREATED!");
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}
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else {
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System.out.println("FILE ALREADY EXIST!!");
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}
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//entering some data
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System.out.println("ENTER DATA IN FILE~ ");
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String obj=sc.nextLine();
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Scanner sc1 = new Scanner(obj);
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while (sc1.hasNextLine()) {
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String sc2 = sc1.nextLine();
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StringBuilder str = new StringBuilder();
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for (char ch:sc2.toCharArray()) {
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int temp=ch;
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str.append(Integer.toBinaryString(temp));
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}
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System.out.println("YOUR DATA IN BITS LOOKS LIKE~ ");
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System.out.println(str);
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//BIT STUFFING
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int count =0;
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StringBuilder str1 = new StringBuilder();
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for (int i=0;i< str.length();i++)
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{
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if (str.charAt(i)=='1')
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{
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count++;
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str1.append(str.charAt(i));
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if (count == 5)
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{
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str1.append("0");
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count =0;
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}
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}
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else
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{
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str1.append(str.charAt(i));
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count =0;
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}
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}
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System.out.println("AFTER BITSTUFFING~ ");
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System.out.println(str1);
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//DE-STUFFING
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StringBuilder d = new StringBuilder();
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for (int i=0;i< str1.length();i++)
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{
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if (str1.charAt(i)=='1')
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{
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count++;
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d.append(str1.charAt(i));
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if (count == 5)
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{
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count =0;
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i++;
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continue;
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}
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}
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else
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{
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d.append(str1.charAt(i));
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count =0;
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}
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}
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System.out.println("DESTUFFING COMPLETED");
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System.out.println(d);
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// comparison
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if((d.toString().equals(str.toString())))
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{
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System.out.println("THE DATA SEND WAS CORRECT!!");
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}
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else {
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System.out.println("SOMETHING WENT WRONG TRY AGAIN!!");
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}
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}
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sc1.close();
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}
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}
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‎HammingCode.java

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package dcn_lab1;
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import java.util.*;
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public class HammingCode {
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public static void main(String args[])
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{
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int size, hammingCodeSize, errorPosition,arr[],hammingCode[];
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Scanner sc = new Scanner(System.in);
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System.out.println("enter data size (in bits)=");
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size = sc.nextInt();
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arr = new int[size];
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for(int j = 0 ; j < size ; j++) { // INPUT DATA
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System.out.println("Enter " + (size - j) + "-bit of the data=");
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arr[size - j - 1] = sc.nextInt();
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}
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hammingCode = getHammingCode(arr); // store return value to the hammingCode array
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hammingCodeSize = hammingCode.length;
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System.out.println("the entered data is=");
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for(int i = 0 ; i < hammingCodeSize; i++) {
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System.out.print(hammingCode[(hammingCodeSize - i - 1)]);
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}
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System.out.println("enter the position you want to generate error in(if not 0)= ");
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errorPosition = sc.nextInt();
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sc.close();
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if(errorPosition != 0) {
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// alter bit of the user entered position
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hammingCode[errorPosition - 1] = (hammingCode[errorPosition - 1] + 1) % 2;
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}
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System.out.println("the sender data= ");
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for(int k = 0; k < hammingCodeSize; k++) {
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System.out.print(hammingCode[hammingCodeSize - k - 1]);
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}
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System.out.println(); // for next line
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receiveData(hammingCode, hammingCodeSize - arr.length);
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}
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static int[] getHammingCode(int data[]) {
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int returnData[],size,i = 0, parityBits = 0 ,j = 0, k = 0;
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size = data.length;
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while(i < size) {
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// 2 power of parity bits = current position(number of bits traversed + number of parity bits + 1).
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if(Math.pow(2, parityBits) == (i + parityBits + 1)) {
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parityBits++;
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}
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else {
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i++;
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}
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}
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returnData = new int[size + parityBits];
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// initialize returnData array with '2'
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for(i = 1; i <= returnData.length; i++) { // condition to find parity bit location
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if(Math.pow(2, j) == i) {
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returnData[(i - 1)] = 2;
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j++;
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}
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else {
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returnData[(k + j)] = data[k++]; //for odd position
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}
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}
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for(i = 0; i < parityBits; i++) {// use for loop to set even parity bits at parity bit locations
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returnData[((int) Math.pow(2, i)) - 1] = getParityBit(returnData, i);
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}
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return returnData;
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}
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static int getParityBit(int returnData[], int pow) { //return parity bit based on the power
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int parityBit = 0;
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int size = returnData.length;
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for(int i = 0; i < size; i++) {
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if(returnData[i] != 2) {
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int k = (i + 1);
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String str = Integer.toBinaryString(k);
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//Now bit at the 2^(power) location of the binary value of index is 1,
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// we check the value stored at that location. If the value is 1 or 0,
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// we will calculate the parity value.
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int temp = ((Integer.parseInt(str)) / ((int) Math.pow(10, pow))) % 10;
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if(temp == 1) {
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if(returnData[i] == 1) {
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parityBit = (parityBit + 1) % 2;
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}
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}
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}
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}
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return parityBit;
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}
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static void receiveData(int data[], int parityBits) { //Detect error
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int pow;
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int size = data.length;
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int parityArray[] = new int[parityBits];
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String errorLoc = new String(); // for storing the integer value of the error location
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for(pow = 0; pow < parityBits; pow++) {
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for(int i = 0; i < size; i++) { //used for 2^power position
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int j = i + 1;
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String str = Integer.toBinaryString(j);
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int bit = ((Integer.parseInt(str)) / ((int) Math.pow(10, pow))) % 10; //find bit
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if(bit == 1) {
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if(data[i] == 1) {
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parityArray[pow] = (parityArray[pow] + 1) % 2;
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}
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}
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}
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errorLoc = parityArray[pow] + errorLoc;
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}
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int finalLoc = Integer.parseInt(errorLoc, 2);
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// check whether the finalLoc value is 0 or not
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if(finalLoc != 0) {
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System.out.println("error at location= " + finalLoc);
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data[finalLoc - 1] = (data[finalLoc - 1] + 1) % 2;
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System.out.println("After correcting the error, the code is:");
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for(int i = 0; i < size; i++) {
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System.out.print(data[size - i - 1]);
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}
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}
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else {
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System.out.println("no error!!");
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}
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}
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}

‎dcn_lab2.java

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package dcn_lab1;
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import java.util.*;
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import java.io.*;
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class dcn_lab2
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{
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public static void main(String args[])throws IOException
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{
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BufferedReader br=new BufferedReader(new InputStreamReader(System.in));
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String x="";
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dcn_lab2 ob=new dcn_lab2();
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System.out.println("Enter binary sequence:");
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x=br.readLine();
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System.out.println(x);
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System.out.println("Choose a polynomial for divisor:");
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System.out.println("1.CRC-8\n2.CRC-10\n3.ITU-16\n4.ITU-32\n5.Custom polynomial\n");
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int cp=Integer.parseInt(br.readLine());
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switch(cp)
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{
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case 1:ob.findCRC(x,"100000111",8);
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break;
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case 2:ob.findCRC(x,"11000110101",11);
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break;
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case 3:ob.findCRC(x,"10001000000100001",16);
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break;
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case 4:ob.findCRC(x,"10000011100110000010001110110110111",32);
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break;
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case 5:System.out.println("Enter the degree of polynomial:");
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int deg=Integer.parseInt(br.readLine());
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StringBuffer polydeg=new StringBuffer(deg+1);
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for(int i=0;i<=deg;i++)
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polydeg.append('0');
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polydeg.setCharAt(deg, '1');
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System.out.println("Enter -999 to terminate input of powers for x\nEnter the powers of x in the polynomial:");
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int pwrs=Integer.parseInt(br.readLine());
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while(pwrs!=-999)
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{
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pwrs=Integer.parseInt(br.readLine());
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}
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polydeg.reverse();
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String divi=polydeg.toString();
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ob.findCRC(x,divi,deg);
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}
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}
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public void findCRC(String seq,String divi,int deg)
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{
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String crc=seq;
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for(int i=0;i<deg;i++)
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crc=crc+"0";
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int len=divi.length();
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String xfind=crc.substring(0,deg+1);
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String remain="";
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while(len<crc.length())
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{
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StringBuffer polydeg;
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int pwrs=0;
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polydeg.setCharAt(pwrs, '1');
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if(xfind.charAt(0)=='1')
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{
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remain=XOR(xfind,divi,deg+1);
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xfind=remain+crc.charAt(len);
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}
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else
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xfind=xfind.substring(1)+crc.charAt(len);
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len++;
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}
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System.out.println("CRC:"+seq+xfind.substring(1));
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}
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public String XOR(String seq,String divi,int len)
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{
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String remain="";
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for(int i=0;i<len;i++)
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{
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if(seq.charAt(i)==divi.charAt(i))
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remain=remain+"0";
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else
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remain=remain+"1";
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}
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return remain.substring(1);
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}
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}

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