Macro-Based Register Config Helper

Code

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

// Define macros here
#define MASK(LEN)                   ((1U<<(LEN)) - 1)
#define SHIFTED_MASK(POS, LEN)      (MASK(LEN) << (POS))
#define CLEAR_FIELD(POS, LEN)       ((REG) &= ~(SHIFTED_MASK(POS, LEN)))
#define SET_FIELD(REG, POS, LEN, VAL)    \
((REG) = ((REG) & ~(SHIFTED_MASK(POS, LEN))) | ((MASK(LEN) & (VAL)) << (POS)))
#define GET_FIELD(REG, POS, LEN)    (((REG) >> (POS)) & MASK(LEN))
     
uint16_t build_register(uint8_t enable, uint8_t mode, uint8_t speed) {
    // Use macros to set fields
    uint8_t reg = 0;
    SET_FIELD(reg, 0, 1, enable);
    SET_FIELD(reg, 1, 2, mode);
    SET_FIELD(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