17. Extract the Nibble from an 8-bit Register

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

unsigned char extractNibble(unsigned char reg, int pos) {
    uint8_t res = 0 ; 
    if(pos ==0){
        for(int i =0 ; i<4 ; i++){
            int bits = (reg >>i  ) &1 ; 
            res |= (bits <<i ) ; 
        }
    }   
    else{
       for(int i=4 ; i<8  ; i++ ){
        int bits = (reg >> i) &1 ; 
        res |= bits << i-4 ;  
       }
    }
    return res ; 
    
}

int main() {
    unsigned char reg;
    int pos;
    scanf("%hhu %d", &reg, &pos);
    printf("%d", extractNibble(reg, pos));
    return 0;
}