Macro-Based Register Config Helper

Code

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

// Define macros here

uint16_t build_register(uint8_t enable, uint8_t mode, uint8_t speed) {
    // Use macros to set fields
    uint16_t reg;
    int enable_bit_len;
    int mode_bit_len;
    int speed_bit_len;
    int reserved_bit_len;

    enable_bit_len = 1;
    mode_bit_len = 2;
    speed_bit_len = 3;
    reserved_bit_len = 2;

    // Set ENABLE bit
    if (enable) {
        reg |= (1 << 0);
    }

    // Set MODE field
    for (int i=0; i<mode_bit_len; i++) {
        if (mode & (1 << i)) {
            reg |= (1 << i+enable_bit_len);
        } else {
            reg &= ~(1 << i+enable_bit_len);
        }
    }

    // Set SPEED field
    for (int i=0; i<speed_bit_len; i++) {
        if (speed & (1 << i)) {
            reg |= (1 << i+enable_bit_len+mode_bit_len);
        } else {
            reg &= ~(1 << i+enable_bit_len+mode_bit_len);
        }
    }    

    // Set RESERVED field
    for (int i=0; i<reserved_bit_len; i++) {
        reg &= ~(1 << i+enable_bit_len+mode_bit_len+speed_bit_len);
    }
    
    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