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

#include <stdio.h>
#include <stdint.h>
#define mod(x,y)  (x|=(y<<0))
#define sped(x,y) (x|=(y<<3))
#define stats(x,y) (x|=(y<<10))

uint16_t pack_register(uint8_t mode, uint8_t speed, uint8_t status) {
    uint16_t reg = 0;
    mod(reg,mode);
    sped(reg,speed);
    stats(reg,status);
    return reg;
}

int main() {
    uint8_t mode, speed, status;
    scanf("%hhu %hhu %hhu", &mode, &speed, &status);
    //printf("%hhu %hhu %hhu", mode, speed, status);
    uint16_t reg = pack_register(mode, speed, status);
    printf("%u", reg);
    return 0;
}