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Author: Pythonista7

crc.java

@@ -0,0 +1,128 @@
+import java.util.*;
+
+class crc
+{
+
+	
+	public static void main(String args[])
+	{
+		Scanner s=new Scanner(System.in);
+
+		int k,g;
+		System.out.println("Enter  degree of data :");
+		k=s.nextInt();
+		System.out.println("Enter  degree of generator :");
+		g=s.nextInt();
+
+		int data[] = new int [200];	
+		int gen[] = new int [200];
+	
+		//function to input 
+		System.out.println("Enter  data: ");//113659.20
+		data=input(data,k);
+		System.out.println("Enter generator: ");
+		gen=input(gen,g);
+
+		//Pad the input with zeros
+		int codeword[] = new int[200];
+		
+		for(int i=k;i<k+g-1;i++)
+			data[i]=0;
+
+		/*Disp after padding
+		System.out.println("Padded Codeword");
+		for(int i=0;i<k+g-1;i++)
+			System.out.println(codeword[i]);
+		*/
+		//Division part
+		//data=codeword bcause data was padded with zeros and stored in codeword
+		codeword=div(data,gen,k,g);
+		System.out.println("Checksum is :");
+		for(int i=k;i<k+g-1;i++)
+		{
+			data[i]=codeword[i];
+			System.out.println(data[i]);
+		}
+
+		System.out.println("Codeword is :");
+		for(int i=0;i<k+g-1;i++)
+		{
+			System.out.println(data[i]);
+		}
+
+		int codewordR[]=new int[200];
+		int dataR[]=new int[200];
+		System.out.println("RE-ENTER CODEWORD for reciever :");
+		//get user input for codewordR
+		dataR=input(codewordR,k+g-1);
+
+		//divide new codeword with gen
+		codewordR=div(dataR,gen,k,g);
+		int flag=0;
+		//System.out.println("After Division");
+		for(int i=k;i<k+g-1;i++)
+		{	if(codewordR[i]!=0)
+			{	flag=1;
+				
+			}
+			else
+				flag=0;
+			//System.out.println(codewordR[i]);
+		}
+		if(flag==1)
+			System.out.println("ERROR");
+		
+		else
+			System.out.println("NO ERROR");
+	}
+
+	//Input helper function
+	public static int[] input(int arr[],int l)
+	{	Scanner s =new Scanner(System.in);
+		for(int i=0;i<l;i++)
+			arr[i]=s.nextInt();
+		return arr;
+	}
+
+	//Division Helper function,function recieves parameter k as n.
+	public static int[] div(int data[],int gen[],int n,int g)
+	{
+		int k,msb;
+		int r[]=new int[200];		
+
+		for(int i=0;i<g;i++)
+		{
+			r[i]=data[i];
+		}
+
+		for(int i=0;i<n;i++)
+		{
+			k=0;
+			
+			msb=r[i];
+			for(int j=i;j<g+i;j++)
+			{	
+				if(msb==0)
+					r[j]=r[j]^0;
+				else
+					r[j]=r[j]^gen[k];
+
+				k++;
+				
+			}
+		
+			
+			r[g+i]=data[g+i];		
+		}
+	
+
+			
+
+		return r;
+
+	
+	}
+	
+	
+
+}