Macro-Based Register Config Helper

Code

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

// Macro to define the bit position of a field
#define FIELD_POSITION(field) field##_POS

// Macro to define the bit width of a field
#define FIELD_WIDTH(field) field##_WID

// Macro to create a value masked and shifted correctly for a field
#define FIELD_VAL(field, value) \
    (((value) & ((1 << FIELD_WIDTH(field)) - 1)) << FIELD_POSITION(field))

// Define the position and width for each field based on the layout above
#define ENABLE_POS 0
#define ENABLE_WID 1
#define MODE_POS   1
#define MODE_WID   2
#define SPEED_POS  3
#define SPEED_WID  3


uint16_t build_register(uint8_t enable, uint8_t mode, uint8_t speed) {
    uint16_t reg = 0;
    // Use the macros to set each field in the register
    reg |= FIELD_VAL(ENABLE, enable);
    reg |= FIELD_VAL(MODE, mode);
    reg |= FIELD_VAL(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