Code:
/**
** Java Program to Implement Booth Algorithm
**/
import java.util.Scanner;
/** Class Booth **/
public class Booth
{
public static Scanner s = new Scanner(System.in);
/** Function to multiply **/
public int multiply(int n1, int n2)
{
int[] m = binary(n1);
int[] m1 = binary(-n1);
int[] r = binary(n2);
int[] A = new int[9];
int[] S = new int[9];
int[] P = new int[9];
for (int i = 0; i < 4; i++)
{
A[i] = m[i];
S[i] = m1[i];
P[i + 4] = r[i];
}
display(A, 'A');
display(S, 'S');
display(P, 'P');
System.out.println();
for (int i = 0; i < 4; i++)
{
if (P[7] == 0 && P[8] == 0);
// do nothing
else if (P[7] == 1 && P[8] == 0)
add(P, S);
else if (P[7] == 0 && P[8] == 1)
add(P, A);
else if (P[7] == 1 && P[8] == 1);
// do nothing
rightShift(P);
display(P, 'P');
}
return getDecimal(P);
}
/** Function to get Decimal equivalent of P **/
public int getDecimal(int[] B)
{
int p = 0;
int t = 1;
for (int i = 7; i >= 0; i--, t *= 2)
p += (B[i] * t);
if (p > 64)
p = -(256 - p);
return p;
}
/** Function to right shift array **/
public void rightShift(int[] A)
{
for (int i = 8; i >= 1; i--)
A[i] = A[i - 1];
}
/** Function to add two binary arrays **/
public void add(int[] A, int[] B)
{
int carry = 0;
for (int i = 8; i >= 0; i--)
{
int temp = A[i] + B[i] + carry;
A[i] = temp % 2;
carry = temp / 2;
}
}
/** Function to get binary of a number **/
public int[] binary(int n)
{
int[] bin = new int[4];
int ctr = 3;
int num = n;
/** for negative numbers 2 complment **/
if (n < 0)
num = 16 + n;
while (num != 0)
{
bin[ctr--] = num % 2;
num /= 2;
}
return bin;
}
/** Function to print array **/
public void display(int[] P, char ch)
{
System.out.print("\n"+ ch +" : ");
for (int i = 0; i < P.length; i++)
{
if (i == 4)
System.out.print(" ");
if (i == 8)
System.out.print(" ");
System.out.print(P[i]);
}
}
/** Main function **/
public static void main (String[] args)
{
Scanner scan = new Scanner(System.in);
System.out.println("Booth Algorithm Test\n");
/** Make an object of Booth class **/
Booth b = new Booth();
/** Accept two integers **/
System.out.println("Enter two integer numbers\n");
int n1 = scan.nextInt();
int n2 = scan.nextInt();
int result = b.multiply(n1, n2);
System.out.println("\n\nResult : "+ n1 +" * "+ n2 +" = "+ result);
}
}
Output:
Booth Algorithm Test
Enter two integer numbers
7 -7
A : 0111 0000 0
S : 1001 0000 0
P : 0000 1001 0
P : 1100 1100 1
P : 0001 1110 0
P : 0000 1111 0
P : 1100 1111 1
Result : 7 * -7 = -49
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