Macro-Based Register Config Helper

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

// Field shifts
#define ENABLE_SHIFT 0
#define MODE_SHIFT   1
#define SPEED_SHIFT  3

// Field encoders (masked + cast)
#define SET_ENABLE(val) (((uint16_t)(val) & 0x1u) << ENABLE_SHIFT)
#define SET_MODE(val)   (((uint16_t)(val) & 0x3u) << MODE_SHIFT)
#define SET_SPEED(val)  (((uint16_t)(val) & 0x7u) << SPEED_SHIFT)

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

    reg |= SET_ENABLE(enable);
    reg |= SET_MODE(mode);
    reg |= SET_SPEED(speed);

    return reg;
}

int main(void) {
    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;
}