Macro-Based Register Config Helper

Code

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

// Define macros here

#define FIELD_MASK(len) ((1u << (len)) - 1)
#define FIELD_MASK_AT(pos, len) (FIELD_MASK(len) << (pos))
#define SET_VALUE(reg, pos, len, value) ((reg) = ((reg) & ~FIELD_MASK_AT((pos), (len))) | ((value) & FIELD_MASK(len))<<(pos))

uint16_t build_register(uint8_t enable, uint8_t mode, uint8_t speed) {
    // Use macros to set fields

    uint16_t reg = 0;
    
    // for enable:
    SET_VALUE(reg, 0, 1, enable);

    // for mode:
    SET_VALUE(reg, 1, 2, mode);

    // for speed:
    SET_VALUE(reg, 3, 3, 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