17. Extract the Nibble from an 8-bit Register

#include <stdio.h>

unsigned char extractNibble(unsigned char reg, int pos) {
    // Write your code here
    unsigned char mask_upper = 0xF0;
    unsigned char mask_lower = 0x0F;
    if(pos == 1)
    {
        return ((reg & mask_upper >> 4));
    }
    if(pos == 0)
    {
        return (reg & mask_lower);
    }
}

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