Register Bitfields Using Struct Overlay

Code

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

typedef union {
    struct {
        uint8_t enable    : 1;
        uint8_t mode      : 2;
        uint8_t interrupt : 1;
        uint8_t reserved  : 4;
    } bits;
    uint8_t reg;
} ControlRegister;


int main() {
    uint8_t e, m, i;
    scanf("%hhu %hhu %hhu", &e, &m, &i);
    ControlRegister *c;
    c->bits.enable=e;
    c->bits.mode=m;
    c->bits.interrupt=i;
    c->bits.reserved=0;
    printf("%hhu",c->reg);
    // Construct and print register value
    return 0;
}

Solving Approach