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) {
    uint16_t reg = 0;
    for (size_t i = 0; i <= 15; i++)
    {
        if(i <= 2)
        {
            reg |= (mode << 0);
        } else if (i >= 3 && i <= 7)
        {
            reg |= (speed << 3);
        } else if (i >= 10 && i <= 15)
        {
            reg |= (status << 10);
        }
    }
    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;
}