Macro-Based Register Config Helper

Code

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

// Bit positions
#define ENABLE_POS 0
#define MODE_POS   1
#define SPEED_POS  3

// Field masks (width masks)
#define ENABLE_MASK (0x1U)  // 1 bit
#define MODE_MASK   (0x3U)  // 2 bits
#define SPEED_MASK  (0x7U)  // 3 bits

// Macros to place values into fields
#define SET_ENABLE(x)  (((x) & ENABLE_MASK) << ENABLE_POS)
#define SET_MODE(x)    (((x) & MODE_MASK)   << MODE_POS)
#define SET_SPEED(x)   (((x) & SPEED_MASK)  << SPEED_POS)

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() {
    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