Macro-Based Register Config Helper

Code

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

uint16_t build_register(uint8_t enable, uint8_t mode, uint8_t speed) {
    uint16_t reg = 0;

    for (int i = 0; i < 8; i++) {
        switch (i) {
            case 0: { // enable -> bit 0
                uint16_t bit = (enable >> 0) & 1U;
                reg |= (bit << 0);
                break;
            }
            case 1: { // mode bit0 -> bit 1
                uint16_t bit = (mode >> 0) & 1U;
                reg |= (bit << 1);
                break;
            }
            case 2: { // mode bit1 -> bit 2
                uint16_t bit = (mode >> 1) & 1U;
                reg |= (bit << 2);
                break;
            }
            case 3: { // speed bit0 -> bit 3
                uint16_t bit = (speed >> 0) & 1U;
                reg |= (bit << 3);
                break;
            }
            case 4: { // speed bit1 -> bit 4
                uint16_t bit = (speed >> 1) & 1U;
                reg |= (bit << 4);
                break;
            }
            case 5: { // speed bit2 -> bit 5
                uint16_t bit = (speed >> 2) & 1U;
                reg |= (bit << 5);
                break;
            }
            case 6:
            case 7:
            default:
                // leave as 0
                break;
        }
    }

    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\n", reg);
    return 0;
}

Solving Approach