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

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

typedef union {
    uint16_t ALL; 

    // 2. Access individual bits
    struct {
        uint16_t MODE    : 3;  // Bits 0-2
        uint16_t Speed     : 5;  // Bits 3-7
        uint16_t RESERVED  : 2;  // Bit 8-9
        uint16_t STATUS    : 6 ; // Bits 10-15
    } BITS;

} ControlRegister_t;

uint16_t pack_register(uint8_t mode, uint8_t speed, uint8_t status) {
    // Your logic here
    ControlRegister_t reg;
    reg.BITS.MODE=mode;
    reg.BITS.Speed=speed;
    reg.BITS.STATUS=status;
    return reg.ALL;
    
}

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;
}