27. Extract Bit Field from 16-bit Register

#include <stdio.h>
#include <stdint.h>
#define POS 4
#define NUM 5

uint8_t extract_field(uint16_t reg) {
    uint16_t mask = (1U<<NUM)-1;
    uint16_t field = (reg>>POS) & mask;
    return field;
}

int main() {
    uint16_t reg;
    scanf("%hx", &reg);
    printf("%u", extract_field(reg));
    return 0;
}