static int time = 0;

int getpitch(int offset)
{
    return 440 * 2 ^ ((offset - 48) / 12);
}

int pwm(int offset, int w = 50)
{
    return (time * getpitch(offset))%100 > w ? 1 : 0;
}

int tune()
{
    int t = time * 8;
    int w = 0;

    if (t%100 > 90 && t%100 < 95)
        w = w + rand()%2;

    if (t%80 < 50)
        w = w + rand()%2;

    if (t%40 > 20 && t%40 < 25)
        w = w + pwm(12);


    if (t%40 > 25 && t%40 < 30)
        w = w + pwm(0);

    return w;
}