## Display Device Driver Reference for OS/2

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### Physical Device Driver Initialization

The IOCtl described below supports the same class of functions as the Presentation Manager dynamic link enable entry point. It is called to fill in the Call Vector Table for the BVH. The call returns an error if the physical device driver detects that the adapter is not present.

Category 3

Function 73h

Purpose

To initialize the Call Vector Table.

Parameter Block Format

None.

Data Packet Format

         DWORD   Subfunction
         DWORD   Parameter1
         DWORD   Parameter2
         WORD    ReturnCode

Subfunction

The Presentation Manager enables the subfunction number. Its value must be 1 to start the Presentation Manager Fill Logical Device Block subfunction. All pieces of the BVH must support this function. Pieces of the BVH that do not support the Presentation Manager interface do not need to support the other functions. Any function not supported should return PMERR_DEV_FUNC_ NOT_INSTALLED.

Parameter1 for Subfunction = 1

Far pointer to this structure:

         DWORD   Engine Version
         DWORD   Count of Table Functions

Engine Version Version of the Presentation Manager Graphics Engine

Count of Table Functions Number of entries in the passed dispatch table. The physical device driver can only write this many entries into the table.

Parameter2 for Subfunction=1

Far pointer to this structure:

         DWORD   Flags Pointer
         DWORD   Call Vector Table

Flags Pointer Pointer to where the flags controlling calls to the Fill Physical Device Block function go.

Call Vector Table Pointer to the default dispatch table containing the addresses of the default handler functions and the functions supported by this component. Each entry in the Call Vector Table is the far address of a Video Device Handler function, which must be callable from Ring 3. The address of the nth BVH function is the nth DWORD in the table, beginning with Function 0. Refer to the DLL Initialization function for a description of the function numbers.

Remarks

This function is supported by the video device drivers and is called only once for each adapter to be supported by the BVH. A video device handler should determine if the display adapter and that which it supports is present. If not present, this function must return an error. Every part of a BVH must successfully initialize the Call Vector Table for that device to be used by OS/2.