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

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

#define mask1 (((1<<3)-1)<<0)
#define mask2 (((1<<5)-1)<<3)
#define mask3 (((1<<2)-1)<<8)
#define mask4 (((1<<6)-1)<<10)
uint16_t pack_register(uint8_t mode, uint8_t speed, uint8_t status) {
    // Your logic here

    uint16_t reg  = 0;
    reg = ((reg &~(mask1|mask2|mask3|mask4))|\
                    (mode<<0)|\
                    (speed<<3)|\
                    (0<<8)|\
                    (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;
}