17. Extract the Nibble from an 8-bit Register

#include <stdio.h>
#define EXTRACT_LOW_HALF(reg)   (reg & 0x0F)
#define EXTRACT_HIGH_HALF(reg)  (reg >> 4)
unsigned char extractNibble(unsigned char reg, int pos) {
    if( pos == 0 ){
        reg = EXTRACT_LOW_HALF(reg);
    }
    else{
        reg = EXTRACT_HIGH_HALF(reg);
    }
    return reg;
}

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