Booth’s Multiplication Algorithm

// C# code to implement 
// booth's algorithm
using System;
class GFG
{
    // function to perform 
    // adding in the accumulator
    static void add(int []ac, 
                    int []x, 
                    int qrn)
    {
        int i, c = 0;
        
        for (i = 0; i < qrn; i++) 
        {
            
            // updating accumulator
            // with A = A + BR
            ac[i] = ac[i] + x[i] + c;
            
            if (ac[i] > 1) 
            {
                ac[i] = ac[i] % 2;
                c = 1;
            }
            else
                c = 0;
        }
    }
    
    // function to find 
    // the number's complement
    static void complement(int []a, int n)
    {
        int i;
        int []x = new int[8];
        Array.Clear(x, 0, 8);
        x[0] = 1;
        
        for (i = 0; i < n; i++)
        {
            a[i] = (a[i] + 1) % 2;
        }
        add(a, x, n);
    }
    
    // function to perform 
    // right shift
    static void rightShift(int []ac, int []qr,
                           ref int qn, int qrn)
    {
        int temp, i;
        temp = ac[0];
        qn = qr[0];
        
        Console.Write("\t\trightShift\t");
        
        for (i = 0; i < qrn - 1; i++)
        {
            ac[i] = ac[i + 1];
            qr[i] = qr[i + 1];
        }
        qr[qrn - 1] = temp;
    }
    
    // function to display 
    // operations
    static void display(int []ac, 
                        int []qr, 
                        int qrn)
    {
        int i;
        
        // accumulator content
        for (i = qrn - 1; i >= 0; i--)
            Console.Write(ac[i]);
        Console.Write("\t");
        
        // multiplier content
        for (i = qrn - 1; i >= 0; i--)
            Console.Write(qr[i]);
    }
    
    // Function to implement
    // booth's algo
    static void boothAlgorithm(int []br, int []qr, 
                               int []mt, int qrn, 
                               int sc)
    {
    
        int qn = 0;
        int []ac = new int[10];
        Array.Clear(ac, 0, 10);
        
        int temp = 0;
        Console.Write("qn\tq[n + 1]\tBR\t" +
                       "\tAC\tQR\t\tsc\n");
        Console.Write("\t\t\tinitial\t\t");
        
        display(ac, qr, qrn);
        Console.Write("\t\t" + sc + "\n");
        
        while (sc != 0) 
        {
            Console.Write(qr[0] + "\t" + qn);
            
            // SECOND CONDITION
            if ((qn + qr[0]) == 1)
            {
                if (temp == 0)
                {
                    
                    // subtract BR 
                    // from accumulator
                    add(ac, mt, qrn);
                    Console.Write("\t\tA = A - BR\t");
                    
                    for (int i = qrn - 1; i >= 0; i--)
                        Console.Write(ac[i]);
                    temp = 1;
                }
                
                // THIRD CONDITION
                else if (temp == 1)
                {
                    // add BR to accumulator
                    add(ac, br, qrn);
                    Console.Write("\t\tA = A + BR\t");
                    
                    for (int i = qrn - 1; i >= 0; i--)
                        Console.Write(ac[i]);
                    temp = 0;
                }
                Console.Write("\n\t");
                rightShift(ac, qr, ref qn, qrn);
            }
            
            // FIRST CONDITION
            else if (qn - qr[0] == 0)
                rightShift(ac, qr, 
                           ref qn, qrn);
            
            display(ac, qr, qrn);
            
            Console.Write("\t");
            
            // decrement counter
            sc--;
            Console.Write("\t" + sc + "\n");
        }
    }
    
    // Driver code
    static void Main()
    {
    
        int []mt = new int[10]; 
        int sc, brn, qrn;
        
        // Number of 
        // multiplicand bit
        brn = 4;
        
        // multiplicand
        int []br = new int[]{ 0, 1, 1, 0 };
        
        // copy multiplier 
        // to temp array mt[]
        for (int i = brn - 1; i >= 0; i--)
            mt[i] = br[i]; 
            
        Array.Reverse(br);
    
        complement(mt, brn);
    
        // No. of 
        // multiplier bit
        qrn = 4;
        
        // sequence 
        // counter
        sc = qrn;
        
        // multiplier
        int []qr = new int[]{ 1, 0, 1, 0 };
        Array.Reverse(qr);
    
        boothAlgorithm(br, qr, 
                       mt, qrn, sc);
        
        Console.WriteLine();
        Console.Write("Result = ");
            
        for (int i = qrn - 1; i >= 0; i--)
            Console.Write(qr[i]);
    }
}
// This code is contributed by 
// Manish Shaw(manishshaw1)