L2NormHelper::L2NormHelper(const void* buffer, size_t length)
{
    const char *d = reinterpret_cast<const char*>(buffer), *a = d;
    op_type  = read<int>(d);
    eps = read<float>(d);
    C = read<int>(d);
    H = read<int>(d);
    W = read<int>(d);
    ASSERT(d == a + length);
}