Extract Bit Field from 16-bit Register

Code

#include <stdio.h>
#include <stdint.h>
#include<math.h>
//#include<unistd.h>

uint8_t extract_field(uint16_t reg) {
    // Your logic here
    uint8_t i,j=0,sum=0,f=0;
    for( i=0;i<16;i++)
    {
        if(i>=4 && i<=8)
        {
            if((reg>>i)&1)
            {
            sum=sum+pow(2,j);
            }
            j++;
        }
    }
    return sum;
}

int main() {
    uint16_t reg;
    scanf("%hx", &reg);
    printf("%u", extract_field(reg));
    return 0;
}

Solving Approach