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 *ctrl) {
    unsigned char enable = ctrl->reg & 1U;
    unsigned char priority = ctrl->reg>>2 & 3U;
    unsigned char reserved = ctrl->reg >> 4 & 0xf;

    if(enable == 1 && priority <=2 && reserved == 0) return 1;

    
    return 0;
}

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

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

    return 0;
}