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

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

#define MASK(width) ((1U << (width)) - 1)

uint16_t pack_register(uint8_t mode, uint8_t speed, uint8_t status) {
    // Your logic here

    uint16_t val = 0;

    val |= (mode & MASK(3)) << 0;
    val |= (speed & MASK(5)) << 3;
    val |= (status & MASK(6)) << 10;

    return val;
}

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;
}