17. Extract the Nibble from an 8-bit Register

#include <stdio.h>

unsigned char extractNibble(unsigned char reg, int pos) {
    // Write your code here
    if (pos == 0) {
        int bitmask = (1 << 4) - 1;
        return reg & bitmask;
    }
    else if (pos == 1) {
        int bitmask = 0xF0;
        return (reg & bitmask) >> 4;
    }
    else {

    }
}

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