c++builder 中怎样列出可用的串口号啊（spcomm控件）,该如何处理

#include <registry.hpp>

void __fastcall CrnGetCommPortList(TStrings *lstComm)
{
    lstComm->Clear();

    TRegistry *reg = new TRegistry;
    TStringList *lst = new TStringList;

    try
    {
        reg->RootKey = HKEY_LOCAL_MACHINE;
        reg->OpenKey("HARDWARE\\DEVICEMAP\\SERIALCOMM", true);

        reg->GetValueNames(lst);

        for (int i = 0; i < lst->Count; i++)
            lstComm->Add(reg->ReadString(lst->Strings[i]));
    }
    __finally
    {
        delete reg;
        delete lst;
    }
}

void __fastcall TForm1::Button1Click(TObject *Sender)
{
    CrnGetCommPortList(Memo1->Lines);
}