Ubuntu Manpage: svgalib - a low level graphics library for linux

NAME

       svgalib - a low level graphics library for linux

       0. Introduction
       1. Installation
       2. How to use svgalib
       3. Description of svgalib functions
       4. Overview of supported SVGA chipsets and modes
       5. Detailed comments on certain device drivers
       6. Goals
       7. References (location of latest version, apps etc.)
       8. Known bugs

0. INTRODUCTION

This is a low level graphics library for Linux, originally based on VGAlib 1.2 by Tommy Frandsen. VGAlib
supported a number of standard VGA graphics modes, as well as Tseng ET4000 high resolution 256-color
modes. As of now, support for many more chipsets has been added. See section 4 Overview of supported SVGA
chipsets and modes

It supports transparent virtual console switching, that is, you can switch consoles to and from text and
graphics mode consoles using alt-[function key]. Also, svgalib corrects most of VGAlib's textmode
corruption behaviour by catching SIGSEGV, SIGFPE, SIGILL, and other fatal signals and ensuring that a
program is running in the currently visible virtual console before setting a graphics mode.

Note right here that SIGUSR1 and SIGUSR2 are used to manage console switching internally in svgalib. You
can not use them in your programs. If your program needs to use one of those signals, svgalib can be
compiled to use other signals, by editing libvga.h

This version includes code to hunt for a free virtual console on its own in case you are not starting the
program from one (but instead over a network or modem login, from within screen(1) or an xterm(1)).
Provided there is a free console, this succeeds if you are root or if the svgalib calling user own the
current console. This is to avoid people not using the console being able to fiddle with it. On graceful
exit the program returns to the console from which it was started. Otherwise it remains in text mode at
the VC which svgalib allocated to allow you to see any error messages. In any case, any I/O the svgalib
makes in text mode (after calling vga_init(3)) will also take place at this new console.

Alas, some games misuse their suid root privilege and run as full root process. svgalib cannot detect
this and allows Joe Blow User to open a new VC on the console. If this annoys you, ROOT_VC_SHORTCUT in
Makefile.cfg allows you to disable allocating a new VC for root (except when he owns the current console)
when you compile svgalib. This is the default.

When the library is used by a program at run-time, first the chipset is detected and the appropriate
driver is used. This means that a graphics program will work on any card that is supported by svgalib, if
the mode it uses is supported by the chipset driver for that card. The library is upwardly compatible
with VGAlib.

The set of drawing functions provided by svgalib itself is limited (unchanged from VGAlib) and
unoptimized; you can however use vga_setpage(3) and vga_getgraphmem(3) (which points to the 64K VGA
framebuffer) in a program or graphics library. A fast external framebuffer graphics library for linear
and banked 1, 2, 3 and 4 bytes per pixel modes is included (it also indirectly supports planar VGA
modes). It is documented in vgagl(7).

One obvious application of the library is a picture viewer. Several are available, along with animation
viewers. See the 7. References at the end of this document.

I have added a simple VGA textmode font restoration utility (restorefont(1)) which may help if you suffer
from XFree86 textmode font corruption. It can also be used to change the textmode font. It comes with
some other textmode utilities: restoretextmode(1) (which saves/restores textmode registers),
restorepalette(1), and the script textmode(1). If you run the savetextmode(1) script to save textmode
information to /tmp, you'll be able to restore textmode by running the textmode(1) script.

1. INSTALLATION

       Installation is easy in general but there are many options and things  you  should  keep  in  mind.  This
       document however assumes that svgalib is already installed.

       If you need information on installation see 0-INSTALL which comes with the svgalib distribution.

       However,  even  after  installation  of  the  library  you might need to configure svgalib using the file
       /etc/vga/libvga.config.   Checkout  section  4  Overview  of  supported  SVGA  chipsets  and  modes   and
       libvga.config(5) for information.

2. HOW TO USE SVGALIB

       For  basic  svgalib usage (no mouse, no raw keyboard) add #include <vga.h> at the beginning your program.
       Use vga_init(3) as your first svgalib call. This will give up root privileges right after initialization,
       making setuid-root binaries relatively safe.

       The  function  vga_getdefaultmode(3)  checks  the environment variable SVGALIB_DEFAULT_MODE for a default
       mode, and returns the corresponding mode number. The environment string can either be a mode number or  a
       mode  name  as in (G640x480x2, G640x480x16, G640x480x256 , G640x480x32K, G640x480x64K, G640x480x16M).  As
       an example, to set the default graphics mode to 640x480, 256 colors, use:

       export SVGALIB_DEFAULT_MODE=G640x480x256

       on the bash(1) command line. If a program needs  just  a  linear  VGA/SVGA  resolution  (as  required  by
       vgagl(7)), only modes where bytesperpixel in the vga_modeinfo structure returned by vga_getmodeinfo(3) is
       greater or equal to 1 should be accepted (this is 0 for tweaked planar 256-color VGA modes).

       Use vga_setmode(graphicsmode) to set a graphics mode. Use vga_setmode(TEXT) to  restore  textmode  before
       program exit.

       Programs  that use svgalib must #include<vga.h>; if they also use the external graphics library vgagl(7),
       you must also #include<vgagl.h>.  Linking must be done with -lvga (and -lvgagl before -lvga, if  vgagl(7)
       is  used).  You  can save binary space by removing the unused chipset drivers in Makefile.cfg if you only
       use specific chipsets. However this reduces the flexibility of svgalib and has a significant effect  only
       when  you  use  the static libraries. You should better use the shared libraries and these will load only
       the really used parts anyway.

       Functions in the vgagl(7) library have the prefix gl_.  Please see vgagl(7) for details.

       There are demos with sources available which will also help to get you started, in recommended  order  of
       interest:  vgatest(6),  keytest(6),  mousetest(6),  eventtest(6), forktest(6), bg_test(6), scrolltest(6),
       speedtest(6), fun(6), spin(6), testlinear(6), lineart(6), testgl(6),  accel(6),  testaccel(6),  plane(6),
       and wrapdemo(6).

       Debugging  your  programs  will  turn out to be rather difficult, because the svgalib application can not
       restore textmode when it returns to the debugger.

       Happy are the users with a serial terminal, X-station, or another  way  to  log  into  the  machine  from
       network. These can use

       textmode </dev/ttyN

       on the console where the program runs and continue.

       However,  the vga_flip(3) function allows you to switch to textmode by entering a call to it blindly into
       your debugger when your program stops in graphics mode.  vga_flip(3) is not very robust though. You shall
       not call it when svgalib is not yet initialized or in textmode.

       Before  continuing  your program, you must then call vga_flip(3) again to return to graphics mode. If the
       program will not make any screen accesses or svgalib calls before it returns to  the  debugger,  you  can
       omit that, of course.

       This will only work if your program and the debugger run in the same virtual linux console.

3. DESCRIPTION OF SVGALIB FUNCTIONS

       Each function has its own section 3 manual page. For a list of vgagl functions see vgagl(7).

   Initialization
       vga_init(3)
              - initialize svgalib library.
       vga_disabledriverreport(3)
              - makes svgalib not emit any startup messages.
       vga_claimvideomemory(3)
              - declare the amount of video memory used.
       vga_safety_fork(3)
              - start a parallel process to restore the console at a crash.
       vga_setchipset(3)
              - force chipset.
       vga_setchipsetandfeatures(3)
              - force chipset and optional parameters.

   Inquire hardware configuration
       vga_getmousetype(3)
              - returns the mouse type configured.
       vga_getcurrentchipset(3)
              - returns the current SVGA chipset.
       vga_getmonitortype(3)
              - returns the monitor type configured.

   Setting video modes
       vga_setmode(3)
              - sets a video mode.
       vga_setdisplaystart(3)
              - set the display start address.
       vga_setlogicalwidth(3)
              - set the logical scanline width.
       vga_setlinearaddressing(3)
              - switch to linear addressing mode.
       vga_setmodeX(3)
              - try to set Mode X-like memory organization .
       vga_ext_set(3)
              - set and query several extended features.
       vga_screenoff(3), vga_screenon(3)
              - turn generation of the video signal on or off.

   Get video mode information
       vga_getxdim(3), vga_getydim(3), vga_getcolors(3)
              - return the current screen resolution.
       vga_white(3)
              - return the color white in the current screen resolution.
       vga_getcurrentmode(3)
              - returns the current video mode.
       vga_hasmode(3)
              - returns if a video mode is supported.
       vga_getmodeinfo(3)
              - returns pointer to mode information structure for a mode.
       vga_getdefaultmode(3)
              - returns the default graphics mode number.
       vga_lastmodenumber(3)
              - returns the last video mode number.
       vga_getmodename(3)
              - return a name for the given video mode.
       vga_getmodenumber(3)
              - return a number for the given video mode.

   Drawing primitives
       vga_clear(3)
              - clear the screen.
       vga_setcolor(3)
              - set the current color.
       vga_setrgbcolor(3)
              - set the current color.
       vga_setegacolor(3)
              - set the current color.
       vga_drawpixel(3)
              - draw a pixel on the screen.
       vga_drawscanline(3)
              - draw a horizontal line of pixels.
       vga_drawscansegment(3)
              - draw a horizontal line of pixels.
       vga_drawline(3)
              - draw a line on the screen.
       vga_getpixel(3)
              - get a pixels value from the screen.
       vga_getscansegment(3)
              - get a list of consecutive pixel values.
       vga_waitretrace(3)
              - wait for vertical retrace.

   Basic (non raw) keyboard I/O
       vga_getch(3)
              - wait for a key.
       vga_getkey(3)
              - read a character from the keyboard without waiting.
       vga_waitevent(3)
              - wait for various I/O events.

   Direct VGA memory access
       vga_setpage(3)
              - set the 64K SVGA page number.
       vga_setreadpage(3)
              - set the 64K SVGA page number.
       vga_setwritepage(3)
              - set the 64K SVGA page number.
       vga_getgraphmem(3)
              - returns the address of the VGA memory.
       vga_copytoplanar256(3)
              - copy linear pixmap into Mode X video memory.
       vga_copytoplanar16(3)
              - copy linear pixmap into VGA 16 color mode video memory.
       vga_copytoplane(3)
              - copy linear pixmap to some planes of VGA 16 color mode video memory.

   Manage color lookup tables
       vga_setpalette(3)
              - set a color in the color lookup table.
       vga_getpalette(3)
              - get a color in the color lookup table.
       vga_setpalvec(3)
              - sets colors in the color lookup table.
       vga_getpalvec(3)
              - gets colors from the color lookup table.

   Mouse handling
       vga_setmousesupport(3)
              - enable mouse support.
       mouse_init(3), mouse_init_return_fd(3)
              - specifically initialize a mouse.
       mouse_close(3)
              - explicitly close a mouse.
       mouse_update(3)
              - updates the mouse state.
       mouse_waitforupdate(3)
              - wait for an mouse update.
       mouse_setscale(3)
              - sets a mouse scale factor.
       mouse_setwrap(3)
              - set what happens at the mouse boundaries.
       mouse_setxrange(3), mouse_setyrange(3)
              - define the boundaries for the mouse cursor.
       mouse_getx(3), mouse_gety(3), mouse_getbutton(3)
              - query the mouse state.
       mouse_setposition(3)
              - set the current mouse position.
       mouse_getposition_6d(3), mouse_setposition_6d(3), mouse_setrange_6d(3)
              - provide an interface to 3d mice.
       mouse_seteventhandler(3), mouse_setdefaulteventhandler(3)
              - set a mouse event handler.

   Raw keyboard handling
       keyboard_init(3), keyboard_init_return_fd(3)
              - initialize the keyboard to raw mode.
       keyboard_close(3)
              - return the keyboard to normal operation from raw mode.
       keyboard_update(3), keyboard_waitforupdate(3)
              - process raw keyboard events.
       keyboard_translatekeys(3)
              - modify scancode mappings in raw keyboard mode.
       keyboard_keypressed(3)
              - check if a key is pressed when in raw keyboard mode.
       keyboard_getstate(3)
              - get a pointer to a buffer holding the state of all keys in raw keyboard mode.
       keyboard_clearstate(3)
              - reset the state of all keys when in raw keyboard mode.
       keyboard_seteventhandler(3), keyboard_setdefaulteventhandler(3)
              - define an event handler for keyboard events in raw mode.

   Joystick handling
       joystick_init(3)
              - initialize and calibrate joysticks.
       joystick_close(3)
              - close a joystick device.
       joystick_update(3)
              - query and process joystick state changes.
       joystick_sethandler(3), joystick_setdefaulthandler(3)
              - define own joystick even handler.
       joystick_getnumaxes(3), joystick_getnumbuttons(3)
              - query the capabilities of a joystick.
       joystick_getaxis(3), joystick_getbutton(3)
              - query the state of a joystick.
       joystick_button1|2|3|4(3), joystick_getb1|2|3|4(3), joystick_x|y|z(3), joystick_getx|y|z(3)
              - convenience macros to query the joystick position.

   Accelerator interface (new style)
       vga_accel(3)
              - calls the graphics accelerator.

   Accelerator interface (old style)
       vga_bitblt(3)
              - copy pixmap on screen using an accelerator.
       vga_fillblt(3)
              - fill rectangular area in video memory with a single color.
       vga_hlinelistblt(3)
              - draw horizontal scan lines.
       vga_imageblt(3)
              - copy a rectangular pixmap from system memory to video memory.
       vga_blitwait(3)
              - wait for any accelerator operation to finish.

   Controlling VC switches
       vga_lockvc(3)
              - disables virtual console switching for safety.
       vga_unlockvc(3)
              - re-enables virtual console switching.
       vga_oktowrite(3)
              - indicates whether the program has direct access to the SVGA.
       vga_runinbackground(3)
              - enable running of the program while there is no VGA access.
       vga_runinbackground_version(3)
              - returns the version of the current background support.

   Debugging aids
       vga_dumpregs(3)
              - dump the contents of the SVGA registers.
       vga_gettextfont(3), vga_puttextfont(3)
              - get/set the font used in text mode.
       vga_gettextmoderegs(3), vga_settextmoderegs(3)
              - get/set the vga state used in text mode.
       vga_flip(3)
              - toggle between text and graphics mode.
       vga_setflipchar(3)
              - set the character causing a vga_flip().

4. OVERVIEW OF SUPPORTED SVGA CHIPSETS AND MODES

VGA and compatibles
320x200x256, and the series of 16-color and non-standard planar 256 color modes supported by VGAlib, as
well as 720x348x2.

ALI2301
Supports 640x480x256, 800x600x256, 1024x768x256 SVGA modes

AT3D (AT25)
Also known as Promotion at25. Popular as the 2D part of a voodoo rush card. As of this writing there are
a few known problems with this driver. Read below.

ARK Logic ARK1000PV/2000PV
Full support, limited RAMDAC support. Only ARK1000PV tested. Supports Clocks and Ramdac lines in config
file.

ATI SVGA (VGA Wonder and friends)
This is no real driver. I do not support any new modes. However it saves additional card setup and thus
allows use of the plain VGA modes even when you are using non standard text modes. It is possible to
enforce use of this driver even on ATI Mach32 but not very useful.

ATI Mach32
The driver by Michael Weller supports all ATI BIOS-defined modes and more... It hits the best out of your
card. Some modes may not have nice default timings but it uses the ATI's EEPROM for custom config or
allows to specify modes in libvga.config(5). Some problems may occur with quite some third party cards
(usually on board) Mach32 based controllers as they do not completely conform to the Mach32 data sheets.
Check out svgalib.mach32(7) (and libvga.config(5)).

ATI Mach64 (rage)
A driver for ATi Mach64 based cards with internal DAC.

Chips and Technologies chipsets 65525, 65535, 65546, 65548, 65550, and 65554 (usually in laptops).
This server was written using the SVGALIB patch from Sergio and Angelo Masci as a starting point. This
version of the code resembled the XFree server code that was used up to XFree 3.1.2. As such it was
incapable of programming the clocks, using linear addressing, Hi-Color, True-Color modes or the hardware
acceleration. All of these features have since been added to the code. The 64200 and 64300 chips are
unsupported, however these chips are very similar to the 6554x chips which are supported.

Cirrus Logic GD542x/3x
All the modes, including 256 color, 32K/64K color, 16M color (3 bytes per pixel) and 32-bit pixel 16M
color modes (5434). Some bitblt functions are supported. The driver doesn't work with mode dumps, but
uses a SVGA abstraction with mode timings like the X drivers.

Genoa(?) GVGA6400 cards.
Supported.

Hercules Stingray 64/Video
Is supported as an ARK2000PV

NV3 driver for the Riva128.
This driver was written by Matan Ziv-Av and is derived from the XFree86 driver by David J. Mckay. It
lacks 24bit modes (can the card do them at all?), acceleration support and pageflipping in threeDKit is
broken.

Oak Technologies OTI-037/67/77/87
Driver by Christopher Wiles; includes 32K color modes for OTI-087.

S3
The driver is not complete, but should work on a number of cards/RAMDACs, and 640x480x256 should work on
most card. The best support is for a 801/805 with AT&T20C490-compatible RAMDAC, and S3-864 + SDAC. All
256/32K/64K/16M works for them (within the bounds of video memory & ramdac restrictions).

The supported cards include S3 Virge and S3 Trio64 cards.

None of the acceleration function is supported yet.

The chip level code should work with the 964/868/968, but most likely the card they come on would use an
unsupported ramdac/clock chip. Support for these chips is slowly being added.

Clocks and Ramdac lines in libvga.config(5) supported.

The maximum pixel clock (in MHz) of the ramdac can be set using a Dacspeed line in the config file. A
reasonable default is assumed if the Dacspeed line is omitted. Clocks should be the same as in XFree86.
Supported ramdac IDs: Sierra32K, SC15025, SDAC, GenDAC, ATT20C490, ATT20C498, IBMRGB52x.

Example:
Clocks 25.175 28.3 40 70 50 75 36 44.9 0 118 77 31.5 110 65 72 93.5
Ramdac att20c490
DacSpeed 85

Also supported, at least in combination with the SC15025/26A ramdac, is the ICD 2061A clock chip. Since
it cannot be autodetected you need to define it in the config file using a Clockchip line. As there is no
way to read the current settings out of the 2061, you have the option to specify the frequency used when
switching back to text mode as second argument in the Clockchip line.

This is especially required if your text mode is an 132 column mode, since these modes use a clock from
the clock chip, while 80 column modes use a fixed clock of 25 MHz. The text mode frequency defaults to
40 MHz, if omitted.

Example:
ClockChip icd2061a 40.0

Trident TVGA 8900C/9000 (and possibly also 8800CS/8900A/B) and also TVGA 9440
Derived from tvgalib by Toomas Losin. TVGA 9440 support by ARK <ark@lhq.com, root@ark.dyn.ml.or>.

Supports 640x480x256, 800x600x256, 1024x768x256 (interlaced and non-interlaced) Might be useful to add
16-color modes (for those equipped with a 512K TVGA9000) for the 8900 and 9000 cards.

320x200x{32K, 64K, 16M}, 640x480x{256, 32K, 64K, 16M}, 800x600x{256, 32K, 64K, 16M}, 1024x768x{16, 256},
800x600x{16, 256, 32K, 64K} modes are supported for the TVGA 9440.

Autodetection can be forced with a:

chipset TVGA memory flags

line in the config file.

memory is the amount of VGA memory in KB, flags is composed of three bits:

bit2 = false, bit1 = false
force 8900.

bit2 = false, bit1 = true
force 9440.

bit2 = true, bit1 = false
force 9680.

bit0 = true
force noninterlaced.

bit0 = false
force interlaced which only matters on 8900's with at least 1M since there is no 512K
interlaced mode on the 8900 or any of the other cards.

Tseng ET4000/ET4000W32(i/p)
Derived from VGAlib; not the same register values. ET4000 register values are not compatible; see
svgalib.et4000(7).

Make sure the colors are right in hicolor mode; the vgatest program should draw the same color bars for
256 and hicolor modes (the DAC type is defined at compilation in et4000.regs or the dynamic registers
file). ET4000/W32 based cards usually have an AT&T or Sierra 15025/6 DAC. With recent W32p based cards,
you might have some luck with the AT&T DAC type. If the high resolution modes don't work, you can try
dumping the registers in DOS using the program in the et4000/ directory and putting them in a file
(/etc/vga/libvga.et4000 is parsed at runtime if DYNAMIC is defined in Makefile.cfg at compilation (this
is default)).

Supported modes are 640x480x256, 800x600x256, 1024x768x256, 640x480x32K, 800x600x32K, 640x480x16M, etc.

Reports of ET4000/W32i/p functionality are welcome.

There may be a problem with the way the hicolor DAC register is handled; dumped registers may use one of
two timing methods, with the value written to the register for a particular DAC for a hicolor mode (in
vgahico.c) being correct for just one of the these methods. As a consequence some dumped resolutions may
work while others don't.

Tseng ET6000
Most modes of which the card is capable are supported. The 8 15 16 24 and 32 bit modes are supported.

The ET6000 has a built in DAC and there is no problem coming from that area. The ET6000 is capable of
acceleration, but this as well as sprites are not yet implemented in the driver.

The driver now uses modelines in libvga.config for user defined modes. It is sometimes useful to add a
modeline for a resolution which does not display well. For example, the G400x600 is too far to the right
of the screen using standard modes. This is corrected by including in libvga.config the line

Modeline "400x600@72" 25.000 400 440 488 520 600 639 644 666

More examples are given below.

This driver was provided by Don Secrest.

VESA
Please read README.vesa and README.lrmi in doc subdirectory of the standard distribution.

Go figure! I turned off autodetection in the release, as a broken bios will be called too, maybe crashing
the machine. Enforce VESA mode by putting a chipset VESA in the end of your libvga.config(5).

Note that it will leave protected mode and call the cards bios opening the door to many hazards.

5. DETAILED COMMENTS ON CERTAIN DEVICE DRIVERS

This section contains detailed information by the authors on certain chipsets.

AT3D (AT25)
Also known as Promotion at25. Popular as the 2D part of a voodoo rush card.

I have written a driver for this chipset, based on the XF86 driver for this chipset.

The programs that work with this driver include all the programs in the demos directory, zgv and dvisvga
(tmview).

I believe it should be easy to make it work on AT24, AT6422.

ATI Mach32
Please see svgalib.mach32(7).

ATI Mach64
The rage.c driver works only on mach64 based cards with internal DAC. The driver might misdetect the
base frequency the card uses, so if when setting any svgalib modes the screen blanks, or complains about
out of bound frequencies, or the display is unsynced, then try adding the option RageDoubleClock to the
config file.

Chips and Technologies chipsets 65525, 65535, 65546, 65548, 65550, and 65554 (usually in laptops).
Please see svgalib.chips(7).

Tseng ET4000/ET4000W32(i/p)
Please see svgalib.et4000(7).

Tseng ET6000
I have only 2 Mbytes of memory on my ET6000 card, so I am not able to get all possible modes running. I
haven't even tried to do all of the modes which I am capable of doing, but I am confident that I can
manage more modes when I have time. I have enough modes working to make the card useful, so I felt it was
worth while to add the driver to svgalib now.

Linear graphics is working on this card, both with and without BACKGROUND enabled, and
vga_runinbackground works.

I decided it was best to quit working on more modes and try to get acceleration and sprites working.

My et6000 card is on a PCI bus. The card will run on a vesa bus, but since I don't have one on my
machine I couldn't develop vesa bus handling. I quit if the bus is a vesa bus.

I check for an et6000 card, which can be unequivocally identified. The et4000 driver does not properly
identify et4000 cards. It thinks the et6000 card is an et4000, but can only run it in vga modes.

I have found the following four modelines to be useful in libvga.config or in ~/.svgalibrc for proper
display of some modes.

Modeline "512x384@79" 25.175 512 560 592 640 384 428 436 494
Modeline "400x300@72" 25.000 400 456 472 520 300 319 332 350 DOUBLESCAN
Modeline "512x480@71" 25.175 512 584 600 656 480 500 510 550
Modeline "400x600@72" 25.000 400 440 488 520 600 639 644 666

Don Secrest <secrest@uiuc.edu> Aug 21, 1999

Oak Technologies OTI-037/67/77/87
First a few comments of me (Michael Weller <eowmob@exp-math.uni-essen.de>):

As of this writing (1.2.8) fixes were made to the oak driver by Frodo Looijaard <frodol@dds.nl> to
reenable OTI-067 support. It is unknown right now if they might have broken OTI-087 support. The author
of the '87 support Christopher Wiles <wileyc@moscow.com> owns no longer an OTI-087 card and can thus no
longer give optimal support to this driver. Thus you might be better off contacting me or Frodo for
questions. If you are a knowledgeable OTI-087 user and experience problems you are welcome to provide
fixes. No user of a OTI-087 is currently known to me, so if you are able to fix problems with the driver
please do so (and contact me) as noone else can.

Michael.

Now back to the original Oak information:

The original OTI driver, which supported the OTI-067/77 at 640x480x256, has been augmented with the
following features:

1) Supported resolutions/colors have been expanded to 640x480x32K, 800x600x256/32K, 1024x768x256, and
1280x1024x16.

2) The OTI-087 (all variants) is now supported. Video memory is correctly recognized.

The driver as it exists now is somewhat schizoid. As the '87 incorporates a completely different set of
extended registers, I found it necessary to split its routines from the others. Further, I did not have
access to either a '67 or a '77 for testing the new resolutions. If using them causes your monitor/video
card to fry, your dog to bite you, and so forth, I warned you. The driver works on my '87, and that's
all I guarantee. Period.

Heh. Now, if someone wants to try them out ... let me know if they work.

New from last release:

32K modes now work for 640x480 and 800x600. I found that the Sierra DAC information in VGADOC3.ZIP is,
well, wrong. But, then again, the information for the '87 was wrong also.

64K modes do not work. I can't even get Oak's BIOS to enter those modes.

I have included a 1280x1024x16 mode, but I haven't tested it. My monitor can't handle that resolution.
According to the documentation, with 2 megs the '87 should be able to do an interlaced 1280x1024x256 ...
again, I couldn't get the BIOS to do the mode. I haven't 2 megs anyway, so there it sits.

I have included routines for entering and leaving linear mode. They should work, but they don't. It
looks like a pointer to the frame buffer is not being passed to SVGALIB. I've been fighting with this
one for a month. If anyone wants to play with this, let me know if it can be make to work. I've got
exams that I need to pass.

Tidbit: I pulled the extended register info out of the video BIOS. When the information thus obtained
failed to work, I procured the OTI-087 data book. It appears that Oak's video BIOS sets various modes
incorrectly (e.g. setting 8-bit color as 4, wrong dot clock frequencies, etc.). Sort of makes me wonder
...

Christopher M. Wiles (a0017097@wsuaix.csc.wsu.edu)
12 September 1994

6. GOALS

I think the ability to use a VGA/SVGA graphics resolution in one virtual console, and being able to
switch to any other virtual console and back makes a fairly useful implementation of graphics modes in
the Linux console.

Programs that use svgalib must be setuid root. I don't know how desirable it is to have this changed;
direct port access can hardly be done without. Root privileges can now be given up right after
initialization. I noticed some unimplemented stuff in the kernel header files that may be useful,
although doing all register I/O via the kernel would incur a significant context-switching overhead. An
alternative might be to have a pseudo /dev/vga device that yields the required permissions when opened,
the device being readable by programs in group vga.

It is important that textmode is restored properly and reliably; it is fairly reliable at the moment, but
fast console switching back and forth between two consoles running graphics can give problems. Wild
virtual console switching also sometimes corrupts the contents of the textmode screen buffer (not the
textmode registers or font). Also if a program crashes it may write into the area where the saved
textmode registers are stored, causing textmode not be restored correctly. It would be a good idea to
somehow store this information in a 'safe' area (say a kernel buffer). Note that the vga_safety_fork(3)
thing has the same idea.

Currently, programs that are in graphics mode are suspended while not in the current virtual console.
Would it be a good idea to let them run in the background, virtualizing framebuffer actions (this should
not be too hard for linear banked SVGA modes)? It would be nice to have, say, a raytracer with a real-
time display run in the background (although just using a separate real-time viewing program is much more
elegant).

Anyone wanting to rewrite it all in a cleaner way (something with loadable kernel modules shouldn't hurt
performance with linear framebuffer/vgagl type applications) is encouraged.

Also, if anyone feels really strongly about a low-resource and truecolor supporting graphical window
environment with cut-and-paste, I believe it would be surprisingly little work to come up with a simple
but very useful client-server system with shmem, the most useful applications being fairly trivial to
write (e.g. shell window, bitmap viewer). And many X apps would port trivially.

This is old information, please be sure to read svgalib.faq(7) if you are interested in further goals.

7. REFERENCES

The latest version of svgalib can be found on sunsite.unc.edu in /pub/Linux/libs/graphics or
tsx-11.mit.edu in /pub/linux/sources/libs as svgalib-X.X.X.tar.gz. As of this writing the latest version
is svgalib-1.4.1.tar.gz. There are countless mirrors of these ftp servers in the world. Certainly a
server close to you will carry it.

The original VGAlib is on tsx-11.mit.edu, pub/linux/sources/libs/vgalib12.tar.Z. tvgalib-1.0.tar.Z is in
the same directory.

SLS has long been distributing an old version of VGAlib. Slackware keeps a fairly up-to-date version of
svgalib, but it may be installed in different directories from what svgalib likes to do by default. The
current svgalib install tries to remove most of this. It also removes /usr/bin/setmclk and
/usr/bin/convfont, which is a security risk if setuid-root. Actually the recent makefiles try to do a
really good job to cleanup the mess which some distributions make.

If you want to recompile the a.out shared library, you will need the DLL 'tools' package (found on
tsx-11.mit.edu, GCC dir). To make it work with recent ELF compiler's you actually need to hand patch it.
You should probably not try to compile it. Compiling the ELF library is deadly simple.

And here is a list of other references which is horribly outdated. There are many more svgalib
applications as well as the directories might have changed. However, these will give you a start point
and names to hunt for on CD's or in ftp archives.

Viewers (in /pub/Linux/apps/graphics/viewers on sunsite.unc.edu):
spic Picture viewer; JPG/PPM/GIF; truecolor; scrolling.
zgv Full-featured viewer with nice file selector.
see-jpeg
Shows picture as it is being built up.
mpeg-linux
svgalib port of the Berkeley MPEG decoder (mpeg_play); it also includes an X binary.
flip FLI/FLC player (supports SVGA-resolution).

Games (in /pub/Linux/games on sunsite.unc.edu):
bdash B*lderdash clone with sound.
sasteroids
Very smooth arcade asteroids game.
yatzy Neat mouse controlled dice game.
vga_cardgames
Collection of graphical card games.
vga_gamespack
Connect4, othello and mines.
wt Free state-of-the-art Doom-like engine.
Maelstrom
A very nice asteroids style game port from Mac.
Koules A game. (I've no idea what it looks like)

Docs
In the vga directory of the SIMTEL MSDOS collection, there is a package called vgadoc3 which is a
collection of VGA/SVGA register information.

The XFree86 driver sources distributed with the link-kit may be helpful.

Miscellaneous
There's an alternative RAW-mode keyboard library by Russell Marks for use with svgalib on
sunsite.unc.edu.

LIBGRX, the extensive framebuffer library by Csaba Biegl distributed with DJGPP, has been ported to
Linux. Contact Hartmut Schirmer (phc27@rz.uni-kiel.d400.de, subject prefix "HARTMUT:"). A more up-to-date
port by Daniel Jackson (djackson@icomp.intel.com) is on sunsite.unc.edu.

The vgalib ghostscript device driver sources can be found on sunsite.unc.edu, /pub/Linux/apps/graphics.
Ghostscript patches from Slackware: ftp.cdrom.com, /pub/linux/misc. gnuplot patches are on
sunsite.unc.edu.

Mitch D'Souza has written font functions that work in 16 color modes and can use VGA textmode (codepage
format) fonts; these can be found in his g3fax package in sunsite.unc.edu. These functions may go into a
later version of svgalib.

8. KNOWN BUGS

This section is most probably outdated, none of these problems are no longer reported.

Using a 132 column textmode may cause graphics modes to fail. Try using something like 80x28.

The console switching doesn't preserve some registers that may be used to draw in planar VGA modes.

Wild console switching can cause the text screen to be corrupted, especially when switching between two
graphics consoles.

On ET4000, having run XFree86 may cause high resolution modes to fail (this is more XFree86's fault).

The Trident probing routine in the XFree86 server may cause standard VGA modes to fail after exiting X on
a Cirrus. Try putting a 'Chipset' line in your Xconfig to avoid the Trident probe, or use the link kit to
build a server without the Trident driver. Saving and restoring the textmode registers with
savetextmode/textmode (restoretextmode) should also work. [Note: svgalib now resets the particular
extended register, but only if the Cirrus driver is used (i.e. the chipset is not forced to VGA)] [This
is fixed in XFree86 v2.1]

Some Paradise VGA cards may not work even in standard VGA modes. Can anyone confirm this?

Piping data into a graphics program has problems. I am not sure why. A pity, since zcatting a 5Mb FLC
file into flip on a 4Mb machine would be fun.

The tseng3.exe DOS program include as source in the svgalib distribution doesn't recognize any modes on
some ET4000 cards. Also ET4000 cards with a Acumos/Cirrus DAC may only work correctly in 64K color mode.

FILES

       /etc/vga/libvga.config
       /etc/vga/libvga.et4000

AUTHOR

       There are many authors of svgalib. This page was edited by Michael Weller <eowmob@exp-math.uni-essen.de>.
       The  original  documentation  and most of svgalib was done by Harm Hanemaayer <H.Hanemaayer@inter.nl.net>
       though.