IDirect3D9Ex::CheckDeviceType

DX9 vtable[9] → HRESULT

IDirect3D9Ex::CheckDeviceType is a method of the COM interface IDirect3D9Ex in Direct3D 9. Its function pointer sits at vtable index 9 — the zero-based slot in that interface's virtual method table, counted from QueryInterface and including every entry inherited from a base interface. It takes 5 parameters (adapter_idx, device_type, display_format, backbuffer_format, windowed) and returns HRESULT.

COM methods are reached through that table rather than by an exported name, so the slot index is what a wrapper, an interface hook or a disassembly listing has to resolve against. The parameter order and types below are the ones this interface declares.