Macro-Based Register Config Helper

Code

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

// Define macros here
// #define ERASE(REG, START, LEN) (REG &= ~((1 << LEN) - 1) << START)
#define ENABLE(REG, PATTERN) (REG |= PATTERN)
#define MODE(REG, PATTERN) (REG |= PATTERN << 1)
#define SPEED(REG, PATTERN) (REG |= PATTERN << 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