Macro-Based Register Config Helper

Code

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

// Define macros here

#define ENABLE(reserved,e) ((reserved) |= (e&0x01)<<0)
#define MODE(reserved,m) ((reserved) |= (m&0x03)<<1)
#define SPEED(reserved,s)   ((reserved)|= (s&0x07)<<3)

uint16_t build_register(uint8_t enable, uint8_t mode, uint8_t speed) {
    // Use macros to set fields
    uint16_t reserved = 0;
    ENABLE(reserved,enable);
    MODE(reserved,mode);
    SPEED(reserved,speed);
    return reserved;
}

int main() {
    uint8_t enable, mode, speed;
    scanf("%hhu %hhu %hhu", &enable, &mode, &speed);

    uint16_t reg = build_register(enable, mode, speed);
    printf("%u", reg);
    return 0;
}

Solving Approach