Delphi执行DOS命令显示到文本框(TMemo)

procedure CmdExecAndView(FileName: string; memo: TMemo);
procedure _AddInfo(mmInfo:TMemo; S: string; var line: string);
var
    i, p: Integer;
begin
    if mmInfo.Lines.Count > 800 then
      mmInfo.Lines.Clear;
    //去掉 \r
    for i := 0 to Length(S) - 1 do
      if S[i] = #13 then S[i] := ' ';
    line := line + S;
    // \n 断行
    p := Pos(#10, line);
    if p > 0 then
    begin
      // \n 前面的加入一行，后面的留到下次
      mmInfo.Lines.Add(Copy(line, 1, p - 1));
      line := Copy(line, p + 1, Length(line) - p);
    end;
end;
var
hReadPipe, hWritePipe: THandle;
si: STARTUPINFO;
lsa: SECURITY_ATTRIBUTES;
pi: PROCESS_INFORMATION;
cchReadBuffer: DWORD;
ph: PChar;
fname: PChar;
line: string;
begin
fname := allocmem(1024);
ph := AllocMem(1024);
lsa.nLength := sizeof(SECURITY_ATTRIBUTES);
lsa.lpSecurityDescriptor := nil;
lsa.bInheritHandle := True;
if CreatePipe(hReadPipe, hWritePipe, @lsa, 0) = false then
    Exit;
fillchar(si, sizeof(STARTUPINFO), 0);
si.cb := sizeof(STARTUPINFO);
si.dwFlags := (STARTF_USESTDHANDLES or STARTF_USESHOWWINDOW);
si.wShowWindow := SW_HIDE;
si.hStdOutput := hWritePipe;
si.hStdError := hWritePipe;
StrPCopy(fname, FileName);
if CreateProcess(nil, fname, nil, nil, true, 0, nil, nil, si, pi) = False then
begin
    FreeMem(ph);
    FreeMem(fname);
    Exit;
end;
CloseHandle(hWritePipe);
while (true) do
begin
    if not PeekNamedPipe(hReadPipe, ph, 1, @cchReadBuffer, nil, nil) then break;
    if cchReadBuffer <> 0 then
    begin
      if ReadFile(hReadPipe, ph^, 512, cchReadBuffer, nil) = false then break;
      ph[cchReadbuffer] := chr(0);
      _AddInfo(memo, ph, line);
    end
    else if (WaitForSingleObject(pi.hProcess, 0) = WAIT_OBJECT_0) then break;
    Application.ProcessMessages;
    Sleep(200);
end;
ph[cchReadBuffer] := chr(0);
_AddInfo(memo, ph, line);
CloseHandle(hReadPipe);
CloseHandle(pi.hThread);
CloseHandle(pi.hProcess);
FreeMem(ph);
FreeMem(fname);
end;
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调用方法（例如）：CmdExecAndView('ping 202.96.134.134',Memo1);

有个问题：如果是CmdExecAndView('ping 202.96.134.134 -t',Memo1);

                  执行起来会不停的输出，没办法停止，点关闭窗口的按钮没反应，只能结束任务，期待着解决这个问题。