I'm writing an Asteroids Atari clone, and I want to figure out how the AI for the asteroids is done.

I have came across that piece of code, but I can't get what it does 100%

if ((float)rand()/(float)RAND_MAX < 0.5) {
        m_Pos.x = -app::getWindowWidth() / 2;
        if ((float)rand()/(float)RAND_MAX < 0.5)
            m_Pos.x = app::getWindowWidth() / 2;
        m_Pos.y = (int) ((float)rand()/(float)RAND_MAX * app::getWindowWidth());
    } else {
        m_Pos.x = (int) ((float)rand()/(float)RAND_MAX * app::getWindowWidth());
        m_Pos.y = -app::getWindowHeight() / 2;
        if (rand() < 0.5)
            m_Pos.y = app::getWindowHeight() / 2;
    }

    m_Vel.x = (float)rand()/(float)RAND_MAX * 2;
    if ((float)rand()/(float)RAND_MAX < 0.5)
    {
        m_Vel.x = -m_Vel.x;
        }

    m_Vel.y =(float)rand()/(float)RAND_MAX * 2;

    if ((float)rand()/(float)RAND_MAX < 0.5)
        m_Vel.y = -m_Vel.y;