Extract the Nibble from an 8-bit Register

#include <stdio.h>
#include <stdint.h>

unsigned char extractNibble(unsigned char reg, int pos) {
    uint8_t mask = 0x0F;
    if (pos != 0) {
        return (reg >> 4) & mask;
    } else {
        return reg & mask;
    }
}

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