Function _mod

crawl-ref/source/message.cc:236–241

};

static int _mod(int num, int denom)
{
    ASSERT(denom > 0);
    div_t res = div(num, denom);
    return res.rem >= 0 ? res.rem : res.rem + denom;
}

template <typename T, int SIZE>
class circ_vec