implementation notes for the ddhel

andyco. 5/30/95.

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introduction

	This document describes some of the nitty gritty implementation details of the ddhel.

what the hel does

	ddhel sits between ddraw and blitlib, extracting ddraw commands and parameters, and passing them
	to the blitlib.  ddhel also does dirty rectangle management for overlay (sprite) emulation.

building the ddhel

	to build, you will need to enlist in -s \\guilo\slm -p dev project. Or, you can modify the SDK32* environment
	variables to point into your msvc20 directories.  See \manhatan\build.mk for the details.
	
	1st, build ddraw
	
		ddraw can be built for ntdebug/ntretail or debug/retail
		
		to use ddraw solely with emulation, (i.e. to run on nt, or for testing on win95) build 
		an nt version  "\manhatan\ddraw\nmake ntdebug"
		
		note that ddraw.h and ddrawi.h get copied to \manhatan\inc\ntdebug. ddraw.lib gets copied to
		\manhatan\lib\ntdebug,
		
		for building ddhel, these files	must be copied to the debug subdirectories \manhatan\inc\debug and
		manhatan\lib\debug.  
		
	next, build bltlib
	
		from \manhatan\blitlib, "nmake retail" or "nmake debug".  Copy the built blitlib to \manhatan\ddhel\lib.
		blitlib.lib is kept checked in to the ddhel project so that it is not part of the regular build (this may
		change in the future)
	
	finally, build ddhel
	
		ddhel is built for either debug or retail (there are no Win95 or NT specific components).  you will need 
		both the ddraw.dll and ddhel.dll to use the ddhel (this may	change in the future) 
		
entry and exit points for the ddhel

	HELInit() is called by ddraw when ddhel is loaded.  ddhel passes back pointers to its callback functions 
	(the my... functions in ddhel.c).  ddraw then communicates with ddhel via these callbacks.  before the ddhel
	is unloaded, myDestroyDriver is invoked.