idzio/di-dev.c: Factor out DirectInput device handling

idzio/di-dev.h

@@ -0,0 +1,19 @@
+#pragma once
+
+#include <windows.h>
+#include <dinput.h>
+
+#include <stdint.h>
+
+union idz_di_state {
+    DIJOYSTATE st;
+    uint8_t bytes[sizeof(DIJOYSTATE)];
+};
+
+HRESULT idz_di_dev_start(IDirectInputDevice8W *dev, HWND wnd);
+void idz_di_dev_start_fx(IDirectInputDevice8W *dev, IDirectInputEffect **out);
+HRESULT idz_di_dev_poll(
+        IDirectInputDevice8W *dev,
+        HWND wnd,
+        union idz_di_state *out);
+