Control Register Using Nested Bitfields

Code

#include <stdio.h>

// typedef union {
//     unsigned char reg;
//     struct {
//         unsigned char enable : 1;
//         unsigned char mode : 1;
//         unsigned char priority : 2;
//         unsigned char reserved : 4;
//     } bits;
// } ControlRegister;

// // Write your logic here
// int validate_register(ControlRegister *ctrl) {
//     return 0;
// }

// int main() {
//     ControlRegister ctrl;
//     scanf("%hhx", &ctrl.reg);

//     int result = validate_register(&ctrl);
//     printf("%d", result);

//     return 0;
// }


typedef union{
    unsigned char reg;
    struct{
        unsigned char enable : 1;
        unsigned char mode : 1;
        unsigned char priority : 2;
        unsigned char reserved : 4;
    } bits;
} ControlRegister;

int validate_register(ControlRegister *ctrl){
    if((*ctrl).bits.enable!=1)
        return 0;
    if((*ctrl).bits.priority>2)
        return 0;
    if((*ctrl).bits.reserved != 0)
        return 0;

    return 1;
}


int main(){
    ControlRegister ctrl;
    scanf("%hhx", &ctrl.reg);

    int result = validate_register(&ctrl);
    printf("%d", result);

    return 0;
}

Solving Approach