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

// --- Bit masks (optional, for clarity) ---
#define ENABLE_MASK  (0x1U << ENABLE_POS)   // 1 bit
#define MODE_MASK    (0x3U << MODE_POS)     // 2 bits
#define SPEED_MASK   (0x7U << SPEED_POS)    // 3 bits

// --- Macros to set fields ---
#define SET_ENABLE(x)   ( ((x) & 0x1U) << ENABLE_POS )
#define SET_MODE(x)     ( ((x) & 0x3U) << MODE_POS )
#define SET_SPEED(x)    ( ((x) & 0x7U) << SPEED_POS )

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

    // Pack fields into register
    reg |= SET_ENABLE(enable);
    reg |= SET_MODE(mode);
    reg |= SET_SPEED(speed);
    // Bits 6–7 remain 0 (reserved)

    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);  // print as decimal
    return 0;
}

Solving Approach