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;
int validate_register(ControlRegister *ctrl) {
    // Truy cập toàn bộ byte
    unsigned char value = ctrl->reg;

    // Truy cập từng bit
    unsigned char enable = ctrl->bits.enable;
    unsigned char mode = ctrl->bits.mode;
    unsigned char priority = ctrl->bits.priority;
    unsigned char reserved = ctrl->bits.reserved;

    // Ví dụ validate: enable phải = 1 và priority <= 2
    if(enable == 1 && priority <= 2 ) {
        
       if(reserved==0) return 1; // hợp lệ
       else return 0 ; 
    } else {
        return 0; // không hợp lệ
    }
}

 


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

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

    return 0;
}

Solving Approach