$XFree86: xc/programs/Xserver/hw/xfree86/vga256/vga/Design,v 3.3 1996/12/28 08:19:11 dawes Exp $

This new frame buffer code is designed to rely on the cfb code more than
the previous cfb.banked code. This frame buffer eliminates the need to
compile cfb in two places. This design is more similar to what is being
done by the accelerated servers.

Some of the function in this new frame buffer code have been updated
to reflect some cfb changes that were implemented after cfb.banked
diverged in the pre-R5 days. This should result in improved accuracy
when running the X Test Suite.

The cfb frame buffer code can be roughly broken into two parts. The first
part is the "upper half" which implementes a packed pixel framebuffer. The
second part is the "lower half" which actually performs the rendering in
the frame buffer.

The vga frame buffer simply replaces the lower half of the cfb code with a
version of the functions that perform bank switching as needed. These function
are replaced by overridding the entries in the Screen structure, and also
by specifying the vga function in the GC structures.

Some of the function fromthe upper half are also duplicated here because
they call some of the lower functions directly, thus the cfb version of the
function would not work (sigh 8-().

This frame buffer code pulls in the routines from the "enhanced" directory
and renames some of them for consistancy.

Some of functions that are "bank aware" have added a check at the begining
that checks to see if the Drawable is not a window. If not, then the regular
cfb version of the function is called instead. The cfb routines should be
slightly fast for pixmaps since they don;t have the banking overhead.

Hopefully, this code can be examined further, adn some of the banking macros
can  be eliminated completely. If a function will only be called (of will have
the pixmap case handled by cfb), then it might be possible to eliminte the 
use of the vgaRead/Writeflag, and the addition test that is made each time the
pixel is incremented.

Some of the enhanced function work by performing unbanked operations inside
bank sized regions, and changint he banks only in the outmost loop. This is
similar to the high-level banking design used by the Xsvga X Server. There
may be more opportunities to do this kind optimization on some of the other
routines.

Many of the updates applied to this code involved replacing code with newer
macros that have the same affect, but make the code easier to read. Also,
in many areas (like the GC code), code was replaced with calls to the mi
equivilent which is also used by the current cfb code. Overall, the total
amount of code in this frame buffer code has been reduced from the cfb.banked
code.

This code contains the following files and functions.

BitBlt.s
	WinWin()	This function is optimized assembler and is used
			by the blitting routines.
BitBlt2.s
	PixPix()
	WinPix()
	PixWin()	These functions are optimized assembler and are used
			by the blitting routines.
Box.s
	SpeedUpBox()	This function is optimized assembler and is use for
			solid fills.
Line.s
	SpeedUpBresS()	This function is optimized assembler and is used for
			General line drawing.
SpeedUpBlt.c
	SpeedUpBitBlt()	This function provide a single entry point for the
			optimized blitting function list above.
VHLine.s
	SpeedUpVLine()
	SpeedUpHLine()	These functions are optimized assembler.

fBitBlt.s
	fastBitBltCopy()
			Optimized assembler for non single bank blitting.
			Used by routines in vgaBitBlt.c that do the banking.

fFill.s
	fastFillSolidGXand()
	fastFillSolidGXor()
	fastFillSolidGXxor()
	fastFillSolidGXcopy()
	fastFillSolidGXset()
			Optimized assembler for fast Solid Fill.

fFillSet.s
	fastFillSolidGXset()
			Optimized assembler for fast Solid Fill.

vga.c
	vgaPrintIdent()
	vgaProbe()
	vgaScreenInit()
	vgaEnterLeaveVT()
	vgaCloseScreen()
	vgaAdjustFrame()
	vgaSwitchMode()
			These functions are the XFree86 device interface.

vga8cppl.c
	vga256CopyImagePlane()
			This function is a wrapper to translate paramters
			from a bitblt interface to a copyplane interface. It
			is used by vga256GetImage() for XYPixmap format bitmaps.
	vga256CopyPlane8to1()
			This functions is bank aware. This function is only
			called from vga256CopyPlane() (through cfbBitBlt())
			and from vga256CopyImagePlane(). The destination
			Drawable is always a Pixmap, so only the source
			pointers need to be banked.
vgaBank.s
	vgaSetReadWrite()
	vgaReadWriteNext()
	vgaReadWritePrev()
	vgaSetRead()
	vgaReadNext()
	vgaReadPrev()
	vgaSetWrite()
	vgaWriteNext()
	vgaWritePrev()
	vgaSaveBank()
	vgaRestoreBank()
	vgaPushRead()
	vgaPopRead()	These functions are the banking functions called
			from within the bank aware frame buffer routines.
			These functions manipulate the pointer, and then call
			the chip specific function to actually change the bank.
	
vgaBanks.c
	SpeedUpComputeNext()	Utility function.

vgaBitBlt.c
	vgaBitBlt()		This function performs blits using as
				much of the bank window as possible
				before switching banks.
	OneBankvgaBitBlt()	This function performs bank sized blits
				from the source into a buffer, and then
				performs bank sized blits back once the
				bank has been set for the destination.
	vgaImageRead()		This function performs bank sized reads
				into a buffer.
	vgaImageWrite()		This function performs bank sized writes
				from a buffer.
	vgaPixBitBlt()		This function performs pixmap to pixmap copies.

vgaCmap.c
	vgaListInstalledColormaps()
	vgaStoreColors()
	vgaInstallColormap()
	vgaUninstallColormap()
				Vga implementation of the colormap.
vgaHW.c
	vgaProtect()
	vgaSaveScreen()
	vgaHWRestore()
	vgaHWSave()
	vgaHWInit()
	vgaGetClocks()
				HW specific implementaion routines.
vgabitblt.c
	vga256DoBitblt()	Single interface for multiple blit routines.
	vga256CopyArea()	CopyArea() that uses low level blit.
	vga256CopyPlane1to8()	This function is bank aware.
				This function is only called from
				vga256CopyPlane() (through cfbBitBlt()). The
				source Drawable is always a Pixmap, so
				only the destination pointers need to be banked.
	vga256CopyPlane()	This function is the same as the cfb version,
				except that it references other frame buffer
				functions directly. This function also
				references the low level functions. This
				function will check for a PIXMAP to PIXMAP
				copy and just call the cfb routine instead.
vgablt.c
	speedupvga256DoBitbltCopy()
	MROP_NAME(vga256DoBitblt)()	These functions are bank aware.
					This function will check for a
					PIXMAP to PIXMAP copy, and just
					call the cfb routine.
vgabltC.
	vga256DoBitbltCopy()	Blit routine that is simplified for the
				case of Copy.

vgabres.s
	fastvga256BresS()	Optimized assembler for drawing lines.

vgabresd.c
	vga256BresD()		This dashed line function is bank aware.

vgabstore.c
	vga256SaveAreas()	This function uses low level blit.
	vga256RestoreAreas()	This function uses low level blit.

vgafillarc.c
	RROP_NAME(vga256FillEllipseSolid)()
				This function is bank aware.
	RROP_NAME(vga256FillArcSliceSolid)()
				This function is bank aware.
	ROP_NAME(vga256PolyFillArcSolid)()
				This function makes direct calls to the
				two above functions. Otherwise, it is
				redundant.

vgafillrct.c
	vga256FillBoxTileOdd()	This function makes direct calls to other
				frame buffer functions. Otherwise, it is
				the same as the cfb function.
	vga256FillRectTileOdd()	This function makes direct calls to other
				frame buffer functions. Otherwise, it is
				the same as the cfb function.
	vga256PolyFillRect()	This function make direct reference to other
				frame buffer functions, and it also references
				the low level functions.
vgafillsp.c
	vga256UnnaturalTileFS()	This function make direct references to
				other frame buffer functions. Otherwise, it
				is the same as the cfb function.
	vga256UnnaturalStippleFS()
				This function is bank aware.
	vga2568Stipple32FS()	This function is bank aware.
	vga2568OpaqueStipple32FS()
				This function is bank aware.

vgafuncs.c
	This file contains the initial definition of the CfbfuncRec structure,
	vga256LowlevFuncs.

vgagc.c
	vga256matchCommon()	This function directly references some other
				frame buffer data structures.
	vga256CreateGC()	This function directly references some other
				frame buffer data structures.
	vga256ValidateGC()	This function directly references some other
				frame buffer functions. Otherwise, it is
				redundant.

vgagetsp.c
	vga256GetSpans()	This function is bank aware.

vgaglblt8.c
	vga256PolyGlyphBlt8()	This function make direct calls to other
				frame buffer functions.
	vga256PolyGlyphBlt8Clipped()
				This function is bank aware.

vgaimage.c
	vga256GetImage()	This function calls other frame buffer
				functions directly. Otherwise, it is
				redundant.

vgaline.c
	speedupvga256SegmentSS()
	vga256SegmentSS()
	speedupvga256LineSS()
	vga256LineSS()
				This function is bank aware. It calls
				optimized assembler routines in most cases.

vgalineH.s
	fastvga256HorzS()	Optimized assembler for drawing
				horizontal lines.

vgalineV.s
	fastvga256VertS()	Optimized assembler for drawing
				verticle lines.

vgalined.c
	vga256SegmentSD()
	vga256LineSD()
				This function is bank aware. This function
				will check for the PIXMAP to PIXMAP case
				and just call the cfb routine.

vgaply1rct.c
	RROP_NAME(vga256FillPoly1Rect)()
				This function is bank aware.

vgapntwin.c
	vga256PaintWindow()	This function calls other frame buffer
				functions and cals the low level functions.
	vga256FillBoxSolid()	This function is bank aware, and calls
				the enhanced routines for fast fills.
				This function is very different from cfb.
	vga256FillBoxTile32()	This function is bank aware.
				This function is different from cfb.

vgapntwinS.c
	speedupvga256FillBoxSolid()
				This function calls an optimized
				routine for filling.

vgapolypnt.c
	vga256PolyPoint()	This function is bank aware.

vgapush8.c
	vga256PushPixels8()	This function is bank aware.

vgarctstp8.c
	speedupvga2568FillRectOpaqueStippled32()
	vga2568FillRectOpaqueStippled32()
				This function is bank aware.
	speedupvga2568FillRectTransparentStippled32()
	vga2568FillRectTransparentStippled32()
				This function is bank aware.
	vga2568FillRectStippledUnnatural()
				This function is bank aware.
vgascrinit.c
	vga256FinishScreenInit()
				This function is that same as the cfb
				function, except that is passes 
				vga256BSFuncRec to miInitializeBackingStore().
	vga256ScreenInit()	This function overrides some of the Screen
				structure members with local frame buffer
				routines.
vgasetsp.c
	vga256SetScanline()	This function is bank aware.
	vga256SetSpans()	This function is bank aware. This function
				checks for the PIXMAP to PIXMAP case and just
				calls the cfb routine.

vgasolid.c
	speedupvga256FillRectSolidCopy()
	vga256FillRectSolidCopy()
	RROP_NAME(vga256FillRectSolid)()
				This function is very different from cfb.
	RROP_NAME(vga256SolidSpans)
				This function is bank aware.
vgateblt8.c
	speedupvga256TEGlyphBlt8()
	vga256TEGlyphBlt8()
				This function is bank aware.

vgategblt.c
	vga256TEGlyphBlt()
				This function is bank aware.

vgatile32.c
	MROP_NAME(vga256FillRectTile32)
				This function is bank aware.
	MROP_NAME(vga256Tile32FS)()
				This finction is bank aware. This function
				checks for the PIXMPA to PIXMAP case and just
				calls the cfb routine.

vgatileodd.c
	MROP_NAME(vga256FillBoxTileOdd)
				This function is bank aware.
	MROP_NAME(vga256FillSpanTileOdd)
				This function is bank aware.
	MROP_NAME(vga256FillBoxTile32s)
				This function is bank aware and somewhat
				different from the cfb code.
	MROP_NAME(vga256FillSpanTile32s)
				This function is bank aware and slightly
				different from the cfb code.
vgawindow.c
	vga256CopyWindow()	This function calls a low level routine.

vgazerarc.c
	RROP_NAME(vga256ZeroArcSS8)
				This function is bank aware.
	RROP_NAME (vga256ZeroPolyArcSS8)
				This function calls the previous
				function directly.

vga.h
	Definition of the chip driver interface.

vga256.h
	Function prototypes for the vga256 frame buffer code. Also defines
	the low-level interface structure.

vgaAsm.h
	Defines the base of the virtual frame buffer used to reprsent
	banked addresses. This file is suitable for inclusion in assembly
	files.

vgaBank.h
	Defines the banking interface used by the frame buffer code.

vgaFasm.h
	Some inline assembler to speed up some operations.


$XConsortium: Design /main/4 1996/02/21 18:09:34 kaleb $