Win32 WM_KEYDOWN and WM_KEYUP and statuses getting "stuck"

Question

Below is a code I use to capture what ever the key is being pressed or not and I update the statuses of the keys according to their states. I keep the statues in my simple array of values 0,1,2,3. formatted as: keyboardmap[256] = {0};

Problem is, what ever I try to do, keys keep getting stuck at some point. They never get reset back to zero as if the WM_KEYUP would not fire up properly.

  while (true)
  {

    if ( PeekMessage(&msg, 0, 0, 0, PM_REMOVE) )
    {
      TranslateMessage(&msg);
      DispatchMessage(&msg);

      if (msg.message == WM_QUIT)
      {
        break;
      }

      // Check for keystates and update them.
      if (msg.message == WM_KEYDOWN)
      {
        // Fetch the key state.
        unsigned int keycode = msg.wParam;
        unsigned int cstate = engine.GetKeyState(msg.wParam);

        if (engine.GetKeyState(keycode) == 0)
        {
          engine.SetKeyState(keycode, 1); // Just started pressing.
        }
        else
        {
          engine.SetKeyState(keycode, 2); // Actively pressed down.
        }
      }
      else if (msg.message == WM_KEYUP)
      {
        // Fetch the key state.
        unsigned int keycode = msg.wParam;
        unsigned int cstate = engine.GetKeyState(msg.wParam);

        if ( engine.GetKeyState(keycode) == 2)
        {
          engine.SetKeyState(keycode, 3);
        }
        else
        {
          engine.SetKeyState(keycode, 0);
        }
      }
    }
  }

Answer 1

That's not how the message loop is supposed to be. Use the following example for a game engine where you need to constantly update the game/screen:

WNDCLASSEX wc = { sizeof(WNDCLASSEX) };
wc.lpfnWndProc = WndProc;
wc.hCursor = LoadCursor(NULL, IDC_ARROW);
wc.lpszClassName = L"WindowClass";
RegisterClassEx(&wc);

CreateWindow(...);

MSG msg = { 0 };
//while (msg.message != WM_QUIT) <=== removed in edit
while(true)  //<=== **** edit **** 
{
    if(PeekMessage(&msg, NULL, 0, 0, PM_REMOVE))
    {
        if(msg.message == WM_QUIT) //<=== **** edit **** 
            break;
        TranslateMessage(&msg);
        DispatchMessage(&msg);
    }
    else
    {
        engine.update();
    }
}

Window's messages should be handled in separate window procedure:

LRESULT CALLBACK WndProc(HWND hWnd, UINT msg, WPARAM wParam, LPARAM lParam)
{
    switch (msg)
    {
    case WM_KEYDOWN:
        break;

    case WM_DESTROY:
        PostQuitMessage(0);
        return 0;
    }

    return DefWindowProc(hWnd, msg, wParam, lParam);
}