Extract the Nibble from an 8-bit Register

Code

#include <stdio.h>
#include <cstdint>

#define HNIBBLE 1
#define LNIBBLE 0
#define MASK 0x0F

unsigned char extractNibble(unsigned char reg, int pos) {
    uint8_t nibble;
    if(pos ==HNIBBLE){
      nibble = (reg >> 4) & MASK;
    }
    if(pos ==LNIBBLE){
       nibble= (reg & 0x0F);
    }
    return nibble;
}

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

Solving Approach