Virtual Device Driver Entry Point Structures

Pointers

_pvddepHead points to the head of a chain of VDDEP structres. One is allocated for each VDD the registers an either or both a VDD/VDD or VDD/OS2 entry point. There entry points are used respectively when either a VDHRequestVDD/VDHOpenVDD or DosRequestVDD/DosOpenVDD call is made.

VDDEP field vddep_vddp points to the associated chain of VDDPROC structures. One is allocated for each VDD the registers entry points under the same name.

_phdlVddHead points to the head of a chain of HDLVDD structures. One is allocated for each open VDD. The handle returned is the address of the associated HDLVDD.

_ppddephead points to the head of a chain of PDDEP structures. One is allocated for each Physical Device Driver that registers an entry point for VDD/PDD communication. The entry point is registered using DevHlp_RegisterPDD, and accessed using VDHRequestPDD.

Locations
VDDEPs, VDDPROCs, HDLVDDs and PDDEPs are allocated dynamically from the kernel resident heap.
VM Owner
VDDEP owner id: vddep (0xffd2).

VDDPROC owner id: vddproc (0xffdb).

HDLVDD owner id: vddlr (0xffd7).

PDDEP owner id: vddpddep (0xffda).

Format

VDDEP

┌────────────────┬──────┬──────┬────┬────────────────────────────────────────┐│Field Name      │Offset│Length│Type│Description                             │
├────────────────┼──────┼──────┼────┼────────────────────────────────────────┤
│vddep_szVDD     │+0    │9     │A   │VDD Name                                │
├────────────────┼──────┼──────┼────┼────────────────────────────────────────┤
│vddep_vddp      │+9    │4     │D   │VDD entry points (pointer to VDDPROC)   │
├────────────────┼──────┼──────┼────┼────────────────────────────────────────┤
│vddep_hmte      │+d    │4     │D   │VDD hmte for deregistering if VDD fails │
├────────────────┼──────┼──────┼────┼────────────────────────────────────────┤
│vddep_pvddep    │+11   │4     │D   │Next VDD (pointer to next VDDEP)        │
└────────────────┴──────┴──────┴────┴────────────────────────────────────────┘

VDDPROC

┌────────────────┬──────┬──────┬────┬────────────────────────────────────────┐
│Field Name      │Offset│Length│Type│Description                             │
├────────────────┼──────┼──────┼────┼────────────────────────────────────────┤
│vddproc_pfnvdd  │+0    │4     │D   │Entry point for VDD/VDD comm.           │
├────────────────┼──────┼──────┼────┼────────────────────────────────────────┤
│vddproc_pfnos2  │+4    │4     │D   │Entry point for OS2/VDD comm.           │
├────────────────┼──────┼──────┼────┼────────────────────────────────────────┤
│pvddproc        │+4    │4     │D   │Entry points registered with same name  │
└────────────────┴──────┴──────┴────┴────────────────────────────────────────┘

HDLVDD

┌────────────────┬──────┬──────┬────┬────────────────────────────────────────┐
│Field Name      │Offset│Length│Type│Description                             │
├────────────────┼──────┼──────┼────┼────────────────────────────────────────┤
│hdlvdd_pvddproc │+0    │4     │D   │VDD routine to be called (pointer to    │
│                │      │      │    │VDDPROC)                                │
├────────────────┼──────┼──────┼────┼────────────────────────────────────────┤
│hdlvdd          │+4    │4     │D   │Pointer to next VDD handle;NULL if no   │
│                │      │      │    │more                                    │
└────────────────┴──────┴──────┴────┴────────────────────────────────────────┘

PDDEP

┌────────────────┬──────┬──────┬────┬────────────────────────────────────────┐
│Field Name      │Offset│Length│Type│Description                             │
├────────────────┼──────┼──────┼────┼────────────────────────────────────────┤
│pddep_szPDD     │+0    │9     │A   │PDD name                                │
├────────────────┼──────┼──────┼────┼────────────────────────────────────────┤
│pddep_fpfn      │+9    │4     │D   │Entry point routine                     │
├────────────────┼──────┼──────┼────┼────────────────────────────────────────┤
│pddep_ppddep    │+d    │4     │D   │Next entry point (PDDEP)                │
└────────────────┴──────┴──────┴────┴────────────────────────────────────────┘

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