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) {
    if (ctrl->bits.enable == 0)  return 0;
    unsigned char bit = ((ctrl->bits.priority) & (0x3));
    if(bit == 3) return 0;
    if((ctrl->bits.reserved) != 0) return 0;
    return 1;
}

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

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

    return 0;
}

Solving Approach