Macro-Based Register Config Helper

Code

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

uint16_t reg;

// Define macros here
#define set_enable_bit() (reg |= ( 1 << 0 ))
#define set_mode_bit(val) do{\
                            reg &= ~(0x3U << 1);\
                            reg |= ((val & 0x3U) << 1);\
                            } while(0)
#define set_speed_bit(val) do{\
                            reg &= ~(0x7U << 3);\
                            reg |= ((val & 0x7U) << 3);\
                            } while(0)
uint16_t build_register(uint8_t enable, uint8_t mode, uint8_t speed) {
    reg = 0;
    // Use macros to set fields
    if (enable) {set_enable_bit();}

    set_mode_bit(mode);
    set_speed_bit(speed);
    return reg;
}

int main() {
    uint8_t enable, mode, speed;
    scanf("%hhu %hhu %hhu", &enable, &mode, &speed);

    reg = build_register(enable, mode, speed);
    printf("%u", reg);
    return 0;
}

Solving Approach