Pack Multiple Fields into a 16-bit Control Register

#include <stdio.h>
#include <stdint.h>
#define MODE(x)      (reg |= ((x)<<0))
#define SPEED(x)     (reg |= ((x) <<3))
#define RESERVED(x)  (reg |= ((x) <<8))
#define STATUS(x)    (reg |= ((x)<<10))
uint16_t pack_register(uint8_t mode, uint8_t speed, uint8_t status) {
    // Your logic here
    uint16_t reg=0;
    MODE(mode);
    SPEED(speed);
    STATUS(status);
    return reg;
}

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;
}