Pack Multiple Fields into a 16-bit Control Register

Code

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

#define MODE_MASK 0x7
#define MODE_Pos 0
#define SPEED_MASK 0x1F
#define SPEED_Pos 3
#define STATUS_MASK 0x3F
#define STATUS_Pos 10

uint16_t pack_register(uint8_t mode, uint8_t speed, uint8_t status) {
    uint16_t packed_bits = 0; // This ensures that the reserved bits will be 0.

    packed_bits |= (mode & MODE_MASK) << MODE_Pos;
    packed_bits |= (speed & SPEED_MASK) << SPEED_Pos;
    packed_bits |= (status & STATUS_MASK) << STATUS_Pos;

    return packed_bits;
}

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;
}

Solving Approach