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

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

#define SET_BIT(r, v, p, l) (r |= (v & ((1U << l) - 1)) << p)

uint16_t pack_register(uint8_t mode, uint8_t speed, uint8_t status) {
    uint16_t result = 0;
    SET_BIT(result, mode, 0, 3);
    SET_BIT(result, speed, 3, 5);
    SET_BIT(result, status, 10, 6);
    return result;
}

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;
}