Graphics Adapter Device Drivers

This chapter describes the functions called by individual Graphics Adapter 
Device Drivers (GRADDs), which are designated by the prefix GHI_CMD_. The 
chapter also discusses Enhanced Direct Interface Video Extension (EnDIVE) 
functions, which are designated by the prefix EXT_CMD_. 

Each GRADD has its own exported function called "HWEntry," which is the 
same function type as VMIEntry.  The differences between the VMAN protocol 
(VMI) and the protocol for the GRADDs (GHI) include the following: 

   *  The VMI is a super set of the GHI. 

   *  The ulFunction parameter value changes to the appropriate VMI_CMD_ 
      function name. 
 

 To provide the appropriate user interface, all GRADDs must export a 
 function of the following typedef: 

 
 ULONG  HWEntry(GID gid, ULONG ulFunction, PVOID pIn, PVOID pOut);