HRESULT GetCurrentReading(
    GameInputKind inputKind,
    IGameInputDevice* device,
    IGameInputReading** reading
);

Microsoft::WRL::ComPtr<IGameInput> gameInput;

void PollGamepadInput() noexcept
{
    Microsoft::WRL::ComPtr<IGameInputReading> reading;

    if (SUCCEEDED(gameInput->GetCurrentReading(
        GameInputKindGamepad,
        nullptr,
        &reading)))
    {
        // Application-specific code to process the reading.
    }
}

Microsoft::WRL::ComPtr<IGameInput> gameInput;
Microsoft::WRL::ComPtr<IGameInputDevice> gamepad;

void PollGamepadInput() noexcept
{
    Microsoft::WRL::ComPtr<IGameInputReading> reading;

    if (SUCCEEDED(gameInput->GetCurrentReading(
        GameInputKindGamepad,
        gamepad.Get(),
        &reading)))
    {
        // Lock onto the first device we find input from, since this
        // must be the one the player is using (if it's generating input).
        if (!gamepad)
        {
            reading->GetDevice(&gamepad);
        }

        // Application-specific code to process the reading.
    }

    else
    {
        // Go back to looking for a device to lock onto, if the previous one is gone.
        gamepad = nullptr;
    }
}

Microsoft::WRL::ComPtr<IGameInput> gameInput;
Microsoft::WRL::ComPtr<IGameInputDevice> gamepad;
Microsoft::WRL::ComPtr<IGameInputReading> prevReading;

void PollGamepadInput() noexcept
{
    if (!prevReading)
    {
        if (SUCCEEDED(gameInput->GetCurrentReading(
            GameInputKindGamepad,
            nullptr,
            &prevReading)))
        {
            gamepad.Attach(prevReading->GetDevice());

            // Application-specific code to process the initial reading.
        }
    }

    else
    {
        Microsoft::WRL::ComPtr<IGameInputReading> nextReading;
        HRESULT hr = gameInput->GetNextReading(
            prevReading.Get(),
            GameInputKindGamepad,
            gamepad.Get(),
            &nextReading);

        if (SUCCEEDED(hr))
        {
            // Application-specific code to process the next reading.

            prevReading = nextReading;
        }

        else if (hr != GAMEINPUT_E_READING_NOT_FOUND)
        {
            gamepad = nullptr;
            prevReading = nullptr;
        }
    }
}