## Virtual Device Driver Reference for OS/2

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### VDHOpenPDD Parameter - VDDEntryPoint

VDDEntryPoint (FPFNVDD) Virtual device driver entry point for use by the physical device driver. Since physical device drivers are 16:16 modules, this is a 16:32 entry point.

The interface for the VDDEntryPoint:

     USHORT VDDENTRY VDDEntryPoint (ulFunc, ul1, ul2)

     ENTRY

         ULONG ulFunc - function code

               All function codes are private to a physical device driver/

               virtual device driver pair.

         ULONG ul1 - function/specific;

               If a pointer, it is 16:16, and will generally be an input packet

         ULONG ul2 - function/specific;

               If a pointer, it is 16:16, and will generally be an output packet

     EXIT-SUCCESS  Returns !0

     EXIT-FAILURE  Returns 0