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) {
    unsigned char temp = 0; 
    temp = (ctrl->bits.enable&1U); 
    // printf("temp = %X", temp); 
    if (temp == 1){
        // ctrl->bits.enable = temp;
        temp = ctrl->bits.priority&3; 
        if (temp < 3){
            temp = ctrl->bits.reserved&15; 
            if (temp ==0){
                return 1; 
            }
        }
    }

    
    return 0;
}

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

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

    return 0;
}

Solving Approach