25. Pack Multiple Fields into a 16-bit Control Register

#include <stdio.h>
#include <stdint.h>

uint16_t pack_register(uint8_t mode, uint8_t speed, uint8_t status) {
    // Your logic here
    union test
    {
        uint16_t total;
        struct
        {
            uint8_t Mode:3;
            uint8_t Speed:5;
            uint8_t Reserved:2;
            uint8_t Status:6;
        };
    };

    test k;
    k.Mode = mode;
    k.Speed = speed;
    k.Reserved = 0;
    k.Status = status;

    return k.total;
}

int main() {
    uint8_t mode, speed, status;
    scanf("%hhu %hhu %hhu", &mode, &speed, &status);

    uint16_t reg = pack_register(mode, speed, status);
    printf("%u", reg);
    return 0;
}