count_multiplication_set_bits.c

#include <stdio.h>
#include <stdint.h>
#include <string.h>

#define SIZE(x) (sizeof(x) * 8)

void int_to_binary(int num,uint8_t bin[],size_t n){

    size_t i=n-1;
    while(num){

        bin[i--]=num & 0x1;
        num>>=1;

    }

}

void print(uint8_t* bin,size_t n){

    for(size_t i=0;i<n;i++){
        printf("%d",bin[i]);
        if(i%4==0) printf(" ");
    }
    printf("\n");

}

size_t count_set_bits(int A,int B){

    size_t size = SIZE(int),s = size;

    uint8_t bin_A[size];
    uint8_t bin_B[size];
    memset(bin_A,0,size);
    memset(bin_B,0,size);

    int_to_binary(A,bin_A,size);
    int_to_binary(B,bin_B,size);

    uint8_t carry=0,count=0,sum=0;
    print(bin_A,size);
    print(bin_B,size);


    for(size_t bit=0;bit<=size;bit++){
        s--;
        sum = 0;
        for(size_t i=s,j=size-1;i<=size-1&&j>=s;i++,j--)

            sum+=bin_A[i]*bin_B[j];

        sum+=carry;
        count+=sum%2;
                printf("%d",sum%2);
        carry=(uint8_t)(sum/2);


    }

    s = size;
    for(size_t bit=0;bit<size;bit++){
        s--;
        sum=0;
        for(size_t i=0,j=s-1;i<s && j>=0;i++,j--)
            sum+=bin_A[i]*bin_B[j];


        sum+=carry;
        count+=sum%2;

                printf("%d",sum%2);
        carry=(uint8_t)(sum/2);
    }

    return count;
}

int main(){



    printf("%zu",count_set_bits(43749823,1232131));





}