Macro-Based Register Config Helper

Code

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

// Shifts
#define ENABLE_SHIFT   0
#define MODE_SHIFT     1
#define SPEED_SHIFT    3

// Masks
#define ENABLE_MASK    (0x1  << ENABLE_SHIFT)
#define MODE_MASK      (0x3  << MODE_SHIFT)
#define SPEED_MASK     (0x7  << SPEED_SHIFT)

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

    // Place fields in correct positions
    reg |= (enable & 0x1) << ENABLE_SHIFT;
    reg |= (mode   & 0x3) << MODE_SHIFT;
    reg |= (speed  & 0x7) << SPEED_SHIFT;

    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