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author | marha <marha@users.sourceforge.net> | 2009-06-28 22:07:26 +0000 |
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committer | marha <marha@users.sourceforge.net> | 2009-06-28 22:07:26 +0000 |
commit | 3562e78743202e43aec8727005182a2558117eca (patch) | |
tree | 8f9113a77d12470c5c851a2a8e4cb02e89df7d43 /xorg-server/hw/xfree86/xf4bpp/NOTES | |
download | vcxsrv-3562e78743202e43aec8727005182a2558117eca.tar.gz vcxsrv-3562e78743202e43aec8727005182a2558117eca.tar.bz2 vcxsrv-3562e78743202e43aec8727005182a2558117eca.zip |
Checked in the following released items:
xkeyboard-config-1.4.tar.gz
ttf-bitstream-vera-1.10.tar.gz
font-alias-1.0.1.tar.gz
font-sun-misc-1.0.0.tar.gz
font-sun-misc-1.0.0.tar.gz
font-sony-misc-1.0.0.tar.gz
font-schumacher-misc-1.0.0.tar.gz
font-mutt-misc-1.0.0.tar.gz
font-misc-misc-1.0.0.tar.gz
font-misc-meltho-1.0.0.tar.gz
font-micro-misc-1.0.0.tar.gz
font-jis-misc-1.0.0.tar.gz
font-isas-misc-1.0.0.tar.gz
font-dec-misc-1.0.0.tar.gz
font-daewoo-misc-1.0.0.tar.gz
font-cursor-misc-1.0.0.tar.gz
font-arabic-misc-1.0.0.tar.gz
font-winitzki-cyrillic-1.0.0.tar.gz
font-misc-cyrillic-1.0.0.tar.gz
font-cronyx-cyrillic-1.0.0.tar.gz
font-screen-cyrillic-1.0.1.tar.gz
font-xfree86-type1-1.0.1.tar.gz
font-adobe-utopia-type1-1.0.1.tar.gz
font-ibm-type1-1.0.0.tar.gz
font-bitstream-type1-1.0.0.tar.gz
font-bitstream-speedo-1.0.0.tar.gz
font-bh-ttf-1.0.0.tar.gz
font-bh-type1-1.0.0.tar.gz
font-bitstream-100dpi-1.0.0.tar.gz
font-bh-lucidatypewriter-100dpi-1.0.0.tar.gz
font-bh-100dpi-1.0.0.tar.gz
font-adobe-utopia-100dpi-1.0.1.tar.gz
font-adobe-100dpi-1.0.0.tar.gz
font-util-1.0.1.tar.gz
font-bitstream-75dpi-1.0.0.tar.gz
font-bh-lucidatypewriter-75dpi-1.0.0.tar.gz
font-adobe-utopia-75dpi-1.0.1.tar.gz
font-bh-75dpi-1.0.0.tar.gz
bdftopcf-1.0.1.tar.gz
font-adobe-75dpi-1.0.0.tar.gz
mkfontscale-1.0.6.tar.gz
openssl-0.9.8k.tar.gz
bigreqsproto-1.0.2.tar.gz
xtrans-1.2.2.tar.gz
resourceproto-1.0.2.tar.gz
inputproto-1.4.4.tar.gz
compositeproto-0.4.tar.gz
damageproto-1.1.0.tar.gz
zlib-1.2.3.tar.gz
xkbcomp-1.0.5.tar.gz
freetype-2.3.9.tar.gz
pthreads-w32-2-8-0-release.tar.gz
pixman-0.12.0.tar.gz
kbproto-1.0.3.tar.gz
evieext-1.0.2.tar.gz
fixesproto-4.0.tar.gz
recordproto-1.13.2.tar.gz
randrproto-1.2.2.tar.gz
scrnsaverproto-1.1.0.tar.gz
renderproto-0.9.3.tar.gz
xcmiscproto-1.1.2.tar.gz
fontsproto-2.0.2.tar.gz
xextproto-7.0.3.tar.gz
xproto-7.0.14.tar.gz
libXdmcp-1.0.2.tar.gz
libxkbfile-1.0.5.tar.gz
libfontenc-1.0.4.tar.gz
libXfont-1.3.4.tar.gz
libX11-1.1.5.tar.gz
libXau-1.0.4.tar.gz
libxcb-1.1.tar.gz
xorg-server-1.5.3.tar.gz
Diffstat (limited to 'xorg-server/hw/xfree86/xf4bpp/NOTES')
-rw-r--r-- | xorg-server/hw/xfree86/xf4bpp/NOTES | 194 |
1 files changed, 194 insertions, 0 deletions
diff --git a/xorg-server/hw/xfree86/xf4bpp/NOTES b/xorg-server/hw/xfree86/xf4bpp/NOTES new file mode 100644 index 000000000..e3b77dcfd --- /dev/null +++ b/xorg-server/hw/xfree86/xf4bpp/NOTES @@ -0,0 +1,194 @@ +This code originally hails from IBM. It was ported to an early XFree86 by +Gertjan Akkerman, whose BUGS file I append here. + +In turn, this is a port of Gertjan's work to the new server design. Among the +changes are: + +- The removal of almost all unreferenced code. +- The removal of this code's own copy of mfb (xf1bpp is used instead). +- The removal of banking support (mibank is used instead). +- External symbols were made static where this was sufficient. +- The remaining external names were renamed to xf4bpp*. +- Several minor cleanups too many to mention here. + +To understate the matter, this code is >UGLY<. This seems inherent in IBM's +corporate culture. Be that as it may, it *does* survive X11R4's xtest +(whatever that means these days...). For now, this is sufficient for 4bpp +support in the new design, but at some point, I'll have to sit down and +rewrite this from scratch. A more technical justification for a rewrite is +that the pixmap format is 8bpp, instead of 4bpp, which is causing me to +pepper the rest of the server with unclean accomodations. + +Marc. + +=============================================================================== +Section 1: From IBM's X11R4 contribution towards XFree86. + +This section describes what I did to obtain a 16 colour vga server. + +I started with the SYSV, ppc, vga and common directories from IBM's X11R4 +contribution. Those directories have the following function: +1. SYSV implements the mouse and keyboard. +2. ppc is a generic layer implementing ddx in terms of drawing operations + through rectangles. (With spans as a boundary case: height = 1.) +3. vga implements a layer of operations drawing through rectangles. +4. common implements ddx initialization and quitting, and screen saving. + +I eliminated SYSV and common since the functionality provided therein is +already provided in XFree86. Since XFree86 is actively being ported to +new operating systems, while X11R4 is out of date, I preferred the XFree86 +code here above the SYSV and common code. +Whatever functionality was still needed from common (default colormap +initialization -- not much code) was moved into ppc. + +Since XFree86 uses the mi-provided software cursor code, IBM's software +cursor code was deleted from ppc and vga. This is a pity, since it is +expected that it is more efficient than mi's code, but the XFree86 mouse and +keyboard code directly call mi, and I do not want to maintain the XFree86 +mouse and keyboard code. + +Since we cannot support a monolithic multi-screen server using all of the +x11r4 contributed code yet, all multi screen code was deleted. This includes +one header file containing a nasty copyright statement. + +Since glyph handling has changed between X11R4 and X11R5, the code handling +glyphs was replaced by appropriate calls to mi. +I hope it can be modified and put back one day. + +Provisionally, some code was added (viz. file vga/offscreen.c) to intercept +calls to the rectangle drawing code when we are switched out of the VT. +I hope this can be replaced by some window tree invalidation and GC validation +scheme. + + +Section 2: BUGS + +This section describes fixed and still unfixed bugs in this code. +All bugs not labeled otherwise also occur in IBM's X11R4 code, and may be of +interest to anybody using that code. + +1. (Fixed.) +I found (and provisionally fixed) a bug in the IBM bitblit code: +In file ddx/ibm/vga/vgaImages.c a function vgaReadColorImage is defined. +When this function is used to read less than 8 pixels starting on a byte +boundary it will always read precisely 8 pixels. +Thus, when space is allocated for 4 or less pixels, it will write beyond +the allocated space. +Since the code is rather convoluted, this may not be apparent at first sight, +but going through the code with an example shows the error. + +2. (Fixed.) +In ppcPixmapFS.c, function ppcStipplePixmapFS there was a bug +regarding the stipple origin: The horizontal origin is added while +the vertical one is subtracted. The horizontal origin should be subtracted +instead of added here. +This bug gets visible when backing-store is enabled and one uses twm: +the submenu icons get truncated on their left hand side. +(In case you wonder why this bug appears: under those circumstances +twm prepares its menus by drawing into an unmapped window. +The miCopyPlane function uses the ppcStipplePixmap (and many others) +to get the plane copied.) +I also fixed this bug in the other routines (ppcOpStipplePixmapFS, +ppcTilePixmapFS) in this file, although I had no visible clues for this. +I hope this is appropriate. + +3. (Fixed.) +I find it suspect that ppcSetSpans gives different output when one +claims that an actually sorted list of spans is unsorted. +The unsorted code is wrong, and should be made to look more like the sorted +code. I.e., use ( xStart - ppt->x ) instead of ( xStart - pbox->x1 ) + +4. (Fixed.) +There used to be another bug that became visible when using twm and backing +store: popping up a submenu, and moving the cursor upwards til it leaves the +submenu, the submenu would disappears, as it should. +But the submenu icon would not get restored, while it should be. +10b. By replacing the clip-computing code in ppcValidateGC by that in +cfbValidateGC, I *finally* fixed the disappearing twm menu icon problem. + +5. Added mfbRegisterCopyplaneProc call. [Its omission was an error on my + part.] + Fixing a server core dump in XTest. + +6. Fixed not-very-high tile bug in function ppcTileRect, file emulTile.c + (I.e., if the tile was higher than the area to be tiled, far too much + was drawn, causing server core dumps in XTest.) + Actually, "savey" ought to be used to determine the height of the tiles in + the top line to be tiled, instead of "pTile->drawable.height". +7. A use of height where width was intended was fixed in ppcTileRect: + "savehcount = w / pTile->drawable.height;" should use "... .width" and + "savehcount = ( x + w - htarget ) / pTile->drawable.height;" too. + +8. Deleted overly clever code in ppcCReduce.c + (All code that tried to pre-compute how alu's could be replaced by + other alu's with inverted colors, etc. was deleted. I think it is + at least wrong for FillSolid.) + +9. Looked at suspicious code in ppcSetSp.c + "tmpx = *pdst;" was never updated during the loop. We took it out of the + initialization position of the for and moved it into the loop. + +10. Add xSrc := GC->patOrg.x + pDrawable.x and ySrc := ... in ppcPixmapFS.c, + functions ppcStipplePixmapFS, ppcOpStipplePixmapFS, and ppcTilePixmapFS. + This because stipple and tile origins are taken relative to the drawable. + Also use a "modulo" function that gets the cases of a negative stipple + or tile offset right. (When the stipple origin is to the right of or + below the origin of the drawable.) + +11. File vgaSolid.c, function vgaFillSolid: + Inverting is XORing with all ones. Not with the color we want to AND/OR + later. So we'll have to set the color to VGA_ALLPLANES + whenever we want to invert existing data, and reset it before the + AND/OR is done. + Also we replaced an outb( 0x3CF, tmp2 ) by the SetVideoGraphicsData( tmp2 ) + it is representing. (Just a cosmetic replacement.) + +12. File vgaImages, function vgaDrawColorImage. + Moved a line "invert_existing_data = TRUE;" two lines down, past a case + label. Now it is also part of the code executed for GXorReverse, as it + should be. + +13. The pixmap FillSpans routines (file ppcPixmapFS.c) got somewhat better + after importing some code from ddx/ibm/vga. (A getbits function that does + wrapping.) + They were wrong for the FillStippled and FillOpaqueStippled modes. + I don't understand the old code. How could it handle stipples of a size not + an exact multiple of 32? (or 8, for that matter.) + +14. In function vgaBitBlt file vgaBitBlt.c, in the shortcuts for + GXSet, GXClear and GXInvert, the source (x0,y0) is accidentally operated + upon by vgaFillSolid, instead of the destination (x1,y1). + +15. Notice that in DoMonoSingle and DoMonoMany in file vgaStipple.c, the left + edge of the square to be stippled is treated wrong. + Correct would be to get the bits with getbits using offset xshift, and + to shift them right (x & 07) places. + [One might wish to use the variable tmp1 at this place, since it had been + set to (x & 07) at this place; but that is already re-used at this point.] + Also note that NeedValX is set wrong: The implicit assumption was that + stipples are more than 8 wide. + This only fixes the problem when miPushPixel is used instead of ppcPushPixel. + I think I should look some more into this. + +16. I took out some code of the CopyArea function, in which a no-op function + was called while a real one was needed. My fix does not completely work, + although it improved the behaviour of GetImage somewhat. + +17. After finding three kinds of errors in this single function, + -- the new kinds being the right side not being always written due to + an incorrect if scope, and the lower end not always being written due + to variables being updated at the wrong place -- + (requiring modifications to be made at at least 10 places, + I decided to REWRITE the body of the ppcTileRect function from scratch. + This version simply computes all relevant margins in advance, and does + not try to reuse temporary variables. I leave that to the compiler. + (This was a maintenance and robustness nightmare anyway.) + +MORE NOTES: + It is funny that there are two files in mi that require compilation + with the proper #defines ( -DXF86VGA16 in my case ): + Besides the obvious mibitblt.c, there is also mipushpxl.c. + + + +$XFree86: xc/programs/Xserver/hw/xfree86/xf4bpp/NOTES,v 1.1.2.2 1998/06/27 15:15:45 dawes Exp $ |