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 val=ctrl->reg;
    if(val&1)
    {
        if((val>>2&3)<=2)
        {
            if(!(val>>4&0xf))
            {
                return 1;
            }
        }
    }
    return 0;
}

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

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

    return 0;
}