Extract the Nibble from an 8-bit Register

Code

#include <stdio.h>
#include <stdint.h>
uint8_t output1;
unsigned char extractNibble(unsigned char reg, int pos) {
    
    uint8_t start_bit;
    if(pos==0){start_bit=0;}
    if(pos==1){start_bit=4;}
    output1=(reg>>start_bit)&0x0f;
    return output1;    
}

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

Solving Approach