Macro-Based Register Config Helper

Code

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

// Define macros here
//step 1: clear section
//step 2: limit mode val
#define SET_ENABLE(reg, val)    reg = (reg & ~(0x01)) | (val & 0x01)
#define SET_MODE(reg, val)      reg = (reg & ~(0x06)) | ((val & 0x03) << 1)
#define SET_SPEED(reg, val)     reg = (reg & ~(0x38)) | ((val & 0x07) << 3)
#define SET_RESERVED(reg, val)  reg = (reg & ~(0xC0)) | ((val & 0x03) << 6)

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

    SET_ENABLE(reg, enable);
    SET_MODE(reg, mode);
    SET_SPEED(reg, speed);
    SET_RESERVED(reg, 0);

    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