Macro-Based Register Config Helper

Code

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

// Define macros here
#define ENABLE(reg, enable) (reg |= ((enable & 0x1) << 0))
#define MODE(reg, mode)     (reg |= ((mode  & 0x3) << 1))
#define SPEED(reg, speed)   (reg |= ((speed & 0x7) << 3))

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

    return reg;
}

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