Macro-Based Register Config Helper

Code

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

// WE DEFINE THE STARTING POSITION OF EACH FIELD IN REGISTER HERE
#define ENABLE_POS 0
#define MODE_POS   1
#define SPEED_POS  3

//WE MOVE THE BITS OF FIELD TO THEIR DEDICATED POSITION IN THE REGISTER
#define ENABLE_MASK (0x01 << ENABLE_POS)
#define MODE_MASK   (0x03 << MODE_POS)
#define SPEED_MASK  (0x07 << SPEED_POS)

//MACROS TO SET THE FIELDS
//FIRST WE CLER THE TARGET FIELD, THEN OR THE NEW VALUE
#define SET_ENABLE(reg, val)  ((reg) = ((reg) & ~ENABLE_MASK) | (((val) << ENABLE_POS) & ENABLE_MASK))
#define SET_MODE(reg, val)  ((reg) = ((reg) & ~MODE_MASK) | (((val) << MODE_POS) & MODE_MASK))
#define SET_SPEED(reg, val)  ((reg) = ((reg) & ~SPEED_MASK) | (((val) << SPEED_POS) & SPEED_MASK))


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