Macro-Based Register Config Helper

Code

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

// Note the & masking makes sure inputs are not too large
// making sure bits 6 and 7 are left cleared
#define SET_ENABLE(n, en)   (n |= (en & 0x01))
#define SET_MODE(n, md)     (n |= ((md & 0x03) << 1))
#define SET_SPEED(n, sp)    (n |= ((sp & 0x07) << 3))

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