67. Control Register Using Nested Bitfields

#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 *reg1) {
    if((*reg1).bits.enable==1 && (*reg1).bits.priority<=2 && (*reg1).bits.reserved==0){
        return 1;
    }
    return 0;
}

int main() {
    ControlRegister ctrl; 
    if (scanf("%hhx", &ctrl.reg) == 1) {
        int result = validate_register(&ctrl);
        printf("%d", result);
    }
}