#include <stdio.h>
#include <math.h>
int a = 0,b = 0, c = 0, a1 = 0, b1 = 0, com[5] = { 1, 0, 0, 0, 0};
int anum[5] = {0}, anumcp[5] = {0}, bnum[5] = {0};
int acomp[5] = {0}, bcomp[5] = {0}, pro[5] = {0}, res[5] = {0};
void binary(){
a1 = fabs(a);
b1 = fabs(b);
int r, r2, i, temp;
for (i = 0; i < 5; i++){
r = a1 % 2;
a1 = a1 / 2;
r2 = b1 % 2;
b1 = b1 / 2;
anum[i] = r;
anumcp[i] = r;
bnum[i] = r2;
if(r2 == 0){
bcomp[i] = 1;
}
if(r == 0){
acomp[i] =1;
}
}
//part for two's complementing
c = 0;
for ( i = 0; i < 5; i++){
res[i] = com[i]+ bcomp[i] + c;
if(res[i] >= 2){
c = 1;
}
else
c = 0;
res[i] = res[i] % 2;
}
for (i = 4; i >= 0; i--){
bcomp[i] = res[i];
}
//in case of negative inputs
if (a < 0){
c = 0;
for (i = 4; i >= 0; i--){
res[i] = 0;
}
for ( i = 0; i < 5; i++){
res[i] = com[i] + acomp[i] + c;
if (res[i] >= 2){
c = 1;
}
else
c = 0;
res[i] = res[i]%2;
}
for (i = 4; i >= 0; i--){
anum[i] = res[i];
anumcp[i] = res[i];
}
}
if(b < 0){
for (i = 0; i < 5; i++){
temp = bnum[i];
bnum[i] = bcomp[i];
bcomp[i] = temp;
}
}
}
void add(int num[]){
int i;
c = 0;
for ( i = 0; i < 5; i++){
res[i] = pro[i] + num[i] + c;
if (res[i] >= 2){
c = 1;
}
else{
c = 0;
}
res[i] = res[i]%2;
}
for (i = 4; i >= 0; i--){
pro[i] = res[i];
printf("%d",pro[i]);
}
printf(":");
for (i = 4; i >= 0; i--){
printf("%d", anumcp[i]);
}
}
void arshift(){//for arithmetic shift right
int temp = pro[4], temp2 = pro[0], i;
for (i = 1; i < 5 ; i++){//shift the MSB of product
pro[i-1] = pro[i];
}
pro[4] = temp;
for (i = 1; i < 5 ; i++){//shift the LSB of product
anumcp[i-1] = anumcp[i];
}
anumcp[4] = temp2;
printf("\nAR-SHIFT: ");//display together
for (i = 4; i >= 0; i--){
printf("%d",pro[i]);
}
printf(":");
for(i = 4; i >= 0; i--){
printf("%d", anumcp[i]);
}
}
void main(){
int i, q = 0;
printf("\t\tBOOTH'S MULTIPLICATION ALGORITHM");
printf("\nEnter two numbers to multiply: ");
printf("\nBoth must be less than 16");
//simulating for two numbers each below 16
do{
printf("\nEnter A: ");
scanf("%d",&a);
printf("Enter B: ");
scanf("%d", &b);
}while(a >=16 || b >=16);
printf("\nExpected product = %d", a * b);
binary();
printf("\n\nBinary Equivalents are: ");
printf("\nA = ");
for (i = 4; i >= 0; i--){
printf("%d", anum[i]);
}
printf("\nB = ");
for (i = 4; i >= 0; i--){
printf("%d", bnum[i]);
}
printf("\nB'+ 1 = ");
for (i = 4; i >= 0; i--){
printf("%d", bcomp[i]);
}
printf("\n\n");
for (i = 0;i < 5; i++){
if (anum[i] == q){//just shift for 00 or 11
printf("\n-->");
arshift();
q = anum[i];
}
else if(anum[i] == 1 && q == 0){//subtract and shift for 10
printf("\n-->");
printf("\nSUB B: ");
add(bcomp);//add two's complement to implement subtraction
arshift();
q = anum[i];
}
else{//add ans shift for 01
printf("\n-->");
printf("\nADD B: ");
add(bnum);
arshift();
q = anum[i];
}
}
printf("\nProduct is = ");
for (i = 4; i >= 0; i--){
printf("%d", pro[i]);
}
for (i = 4; i >= 0; i--){
printf("%d", anumcp[i]);
}
}
