27. Extract Bit Field from 16-bit Register

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

#define BIT 4
#define MASK ((0x1F) << BIT)

#define READ(R,M,B) (((R) & (M)) >> (B))

uint8_t extract_field(uint16_t reg) {
    return READ(reg, MASK, BIT);
}

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