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) {
    
    uint32_t reg = 0;

    uint16_t mode_mask = (((1U << 3U) - 1U) << 0);
    uint16_t speed_mask = (((1U << 5U) - 1U) << 3U);
    uint16_t reserved_mask = (((1U << 2U) - 1U) << 8U);
    uint16_t status_mask = (((1U << 6U) - 1U) << 10U);

    reg &= ~mode_mask;
    reg |= uint16_t(mode);

    reg &= ~speed_mask;
    reg |= (uint16_t(speed) << 3U);

    reg &= ~reserved_mask;

    reg &= ~status_mask;
    reg |= (uint16_t(status) << 10U);

    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;
}