判断线程是否释放

/判断线程是否释放
//返回值：0-已释放；1-正在运行；2-已终止但未释放；
//3-未建立或不存在
function TFrmMain.CheckThreadFreed(aThread: TThread): Byte;
var
i: DWord;
IsQuit: Boolean;
begin
if Assigned(aThread) then
begin
IsQuit := GetExitCodeThread(aThread.Handle, i);
if IsQuit then //If the function succeeds, the return value is nonzero.
//If the function fails, the return value is zero.
begin
if i = STILL_ACTIVE then //If the specified thread has not terminated,
//the termination status returned is STILL_ACTIVE.
Result := 1
else
Result := 2; //aThread未Free，因为Tthread.Destroy中有执行语句
end
else
Result := 0; //可以用GetLastError取得错误 代码
end
else
Result := 3;
end;