#include <cstdint>

const uintptr_t ADDRESS{0x40};

class Color {
    uint8_t* _ptr{};

public:
    Color(uintptr_t address): _ptr{reinterpret_cast<uint8_t*>{address}} {}

    void set_red(uint8_t value) {
        *_ptr = value;
    }
    void set_green(uint8_t value) {
        *(_ptr + 1) = value;
    }
    void set_blue(uint8_t value) {
        *(_ptr + 2) = value;
    }
}

int main() {
    Color color{ADDRESS};
    color.set_red(255);
    color.set_green(127);
    color.set_blue(64);
    return 0;
}