import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
public class crc {
public static void main(String args[]) throws IOException {
InputStreamReader crc = new InputStreamReader(System.in);
BufferedReader br = new BufferedReader(crc);
int[] data_maessage, crc_gen, message, random, transmitter;
int data_bits, gen_bits, total_bits;
/*
* ——————— Here we enter the Number of bit for massage length
* ——————–
*/
System.out.println(”
Enter the Number of bits in message:
“);
data_bits = Integer.parseInt(br.readLine());
data_maessage = new int[data_bits];
/*
* ———————- here we enter the massage in bits
* ———————–
*/
System.out.println(”
Enter the message bits :
“);
for (int i = 0; i < data_bits; i++)
data_maessage[i] = Integer.parseInt(br.readLine());
/*
* --------------------- here we enter how number of the generator Polynomial Division
* means divided ----------------------
*/
System.out.println("
Enter the number of bits in Generetor Polynomial Division :
");
gen_bits = Integer.parseInt(br.readLine());
crc_gen = new int[gen_bits];
/*
* -------------------------here we enter the Generator Polynomial Division bits
* ------------------------
*/
System.out.println("
Enter the Generator Polynomial Division bits :
");
for (int i = 0; i < gen_bits; i++) {
crc_gen[i] = Integer.parseInt(br.readLine());
}
total_bits = data_bits + gen_bits - 1;
message = new int[total_bits];
random = new int[total_bits];
transmitter = new int[total_bits];
/*------------------ CRC GENERATION-----------------------*/
for (int i = 0; i < data_maessage.length; i++) {
message[i] = data_maessage[i];
}
System.out.print("
The Massage bits are :
");
for (int i = 0; i < data_bits; i++) {
// here its print the massage
System.out.println(data_maessage[i]);
}
System.out.print("
The Geberators bits are :
");
for (int i = 0; i < gen_bits; i++) {
// here its print the generator polynomial
System.out.println(crc_gen[i]);
}
/*
* --------------------- append dividend and remainder -------------------------
*/
System.out.print("
The Appended message is :
");
for (int i = 0; i < message.length; i++) {
System.out.print(message[i]);
}
for (int j = 0; j < message.length; j++) {
random[j] = message[j];
}
random = CRC(message, crc_gen, random);
for (int i = 0; i < message.length; i++) {
transmitter[i] = (message[i] ^ random[i]);
}
System.out.println("
The Message is Transmitted from the transmitter :
");
for (int i = 0; i < transmitter.length; i++) {
System.out.print(transmitter[i]);
}
System.out.println("
Enter message of " + total_bits + " bits at receiver end :
");
for (int i = 0; i < transmitter.length; i++) {
transmitter[i] = Integer.parseInt(br.readLine());
}
System.out.println("
The Received message is :
");
for (int i = 0; i < transmitter.length; i++) {
System.out.print(transmitter[i]);
}
for (int j = 0; j < transmitter.length; j++) {
random[j] = transmitter[j];
}
/* ----------------------- ERROR DETECTION ------------------------ */
random = CRC(transmitter, crc_gen, random);
for (int i = 0; i < random.length; i++) {
if (random[i] != 0) {
System.out.println("
There is an error in received data 🙁 .....
");
break;
}
if (i == random.length - 1) {
System.out.println("
Data was received without any error 🙂 .....
");
}
}
System.out.println("Thank you 🙂 and My References are in this projecr which i used for study in References in below the Package name....");
}
public static int[] CRC(int message[], int crc_generator[], int random[]) {
int crc = 0;
while (true) {
for (int i = 0; i < crc_generator.length; i++) {
random[crc + i] = (random[crc + i] ^ crc_generator[i]);
}
while (random[crc] == 0 && crc != random.length - 1) {
crc++;
}
if ((random.length - crc) < crc_generator.length) {
break;
}
}
return random;
}
}
