21CS52 Program 1

package error_detecting;

import java.util.Arrays;
import java.util.Scanner;

public class crc {
	static int[] input(String x) {
		Scanner s = new Scanner(System.in);
		System.out.println("Enter no. of " + x + " bits:");
		int size = s.nextInt();
		int arr[] = new int[size];
		System.out.println("Enter " + x + " bits:");
		for (int i = 0; i < size; i++)
			arr[i] = s.nextInt();
		return arr;
	}

	public static void main(String[] args) {
		int[] data, divisor;
		int tot_length, i;
		Scanner s = new Scanner(System.in);
		data = input("data");
		divisor = input("divisor");
		tot_length = data.length + (divisor.length - 1);
		int crc[] = new int[tot_length];
		int dividend[] = Arrays.copyOf(data, tot_length);
		int reminder[] = Arrays.copyOf(dividend, tot_length);

		reminder = divide(divisor, reminder);
		for (i = 0; i < dividend.length; i++)
			crc[i] = (dividend[i] ^ reminder[i]);
		System.out.println("CRC Code: " + Arrays.toString(crc));
		System.out.println("Enter CRC code of " + (tot_length) + "bits.");
		for (i = 0; i < crc.length; i++) {
			reminder[i] = s.nextInt();
		}
		reminder = divide(divisor, reminder);
		System.out.println(Arrays.binarySearch(reminder, 1) > 0 ? "Error" : "NoError");
		System.out.println("FINISHED");
	}

	static int[] divide(int divisor[], int reminder[]) {
		int cur = 0;
		while (true) {
			for (int i = 0; i < divisor.length; i++)
				reminder[cur + i] = (reminder[cur + i] ^ divisor[i]);
			while (reminder[cur] == 0 && cur != reminder.length - 1)
				cur++;
			if ((reminder.length - cur) < divisor.length)
				break;
		}
		return reminder;
	}
}