unsigned int __thiscall sub_901BD0(struct_this *this, int index)
{
  unsigned int newkey; // eax@2
  unsigned int result; // eax@2

  if ( index )
  {
    if ( index == 1 )
    {
      this->keyone = 2025010528;
      this->keytwo = 1934700547;
      this->keythree = 681844883;
      result = 0;
    }
    else
    {
      this->keyone = 0;
      this->keytwo = 0;
      this->keythree = 0;
      result = 0;
    }
  }
  else
  {
    newkey = this->keyone * this->keytwo + this->keythree;
    this->keyone = newkey;
    result = (newkey >> 16) & 0x7FFF;
  }
  return result;
}