17. Extract the Nibble from an 8-bit Register

#include <stdio.h>

#define LOWER_NIBBLE_MASK 0xF
#define UPPER_NIBBLE_MASK 0xF0

unsigned char extractNibble(unsigned char reg, int pos) {
    return (pos == 0) ? (reg & LOWER_NIBBLE_MASK) : ((reg & UPPER_NIBBLE_MASK) >> 4);
}

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