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 = *(unsigned char*)ctrl;
    if (((temp & 0x01) == 1) && (((temp >> 2) & 0x03) <= 2) && ((temp & 0xF0) == 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