Extract the Nibble from an 8-bit Register

Code

#include <stdio.h>

#define LOW 0
#define UP 1

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

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

Solving Approach