27. Extract Bit Field from 16-bit Register

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

uint16_t extract_field(uint16_t reg)
{
  uint8_t mask = ((1U << 5) - 1); // 0x1F

  return (reg >> 4) & (mask);
}

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