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vga_flip(3) [v7 man page]

vga_flip(3)							Svgalib User Manual						       vga_flip(3)

NAME
vga_flip - toggle between text and graphics mode SYNOPSIS
#include <vga.h> int vga_flip(void); DESCRIPTION
switches between graphics and text mode without destroying the screen contents. This makes it possible for your application to use both text and graphics output. However, This is an old vgalib function. You should really only use it for debugging as it runs extremely unstable because svgalib now does its own virtual console management. If you want to perform a similar action, save the current screen contents with ordinary memory copy operation to the frame buffer or gl_getbox(3), set vga_setmode(TEXT), then call vga_setmode(3) to return to graphics operation and restore the screen contents with memory or gl_putbox(3). One could also use vga_drawscansegment(3) and vga_getscansegment(3) calls. However, avoid any calls to vga_flip() in your applications. The function always returns 0, a fact on which you shouldn't rely. It might be useful if you are debugging one of your svgalib applications though. If your program reaches a breakpoint while in graphics mode, you can switch to text mode with the gdb command print vga_flip() and later restore the graphics screen contents with the same command. It is useful to define the following alias in gdb: define flip <Return> print vga_flip() <Return> end <Return> SEE ALSO
svgalib(7), vgagl(7), libvga.config(5), vga_init(3), vga_setflipchar(3), vga_drawscanline(3), vga_drawscansegment(3), vga_getscanseg- ment(3), gl_getbox(3), gl_putbox(3) AUTHOR
This manual page was edited by Michael Weller <eowmob@exp-math.uni-essen.de>. The exact source of the referenced function as well as of the original documentation is unknown. It is very likely that both are at least to some extent are due to Harm Hanemaayer <H.Hanemaayer@inter.nl.net>. Occasionally this might be wrong. I hereby asked to be excused by the original author and will happily accept any additions or corrections to this first version of the svgalib manual. Svgalib (>;= 1.2.11) 27 July 1997 vga_flip(3)

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vga_safety_fork(3)						Svgalib User Manual						vga_safety_fork(3)

NAME
vga_safety_fork - start a parallel process to restore the console at a crash SYNOPSIS
#include <vga.h> void vga_safety_fork(void (*shutdown_routine)(void)) DESCRIPTION
Calling this at the start of a program results in a better chance of textmode being restored in case of a crash. However it has to raise the iopl level to 3 to work. This is a small security breach as it is inherited to any programs you fork of. However, some SVGA card driv- ers have to use iopl(3) anyway. If you use it call that function as the very first vga_ function. Call it right before vga_init (3). Note that vga_safety_fork() will already enter a graphicsmode. (For font and grafix state saving). Don't overestimate the power of this func- tion. Your application will continue to run in background while a foreground application will restore a usable screen and graphics mode in case of a crash. The forktest(6) demo shows the principal operation. (*shutdown_routine)() is called when the system crashes. However, realize that the call will take in a forked copy of your program, you'll not have access to any globals modified after the vga_safety_fork() call! SEE ALSO
svgalib(7), vgagl(7), libvga.config(5), forktest(6), vga_init(3), AUTHOR
This manual page was edited by Michael Weller <eowmob@exp-math.uni-essen.de>. The exact source of the referenced function as well as of the original documentation is unknown. It is very likely that both are at least to some extent are due to Harm Hanemaayer <H.Hanemaayer@inter.nl.net>. Occasionally this might be wrong. I hereby asked to be excused by the original author and will happily accept any additions or corrections to this first version of the svgalib manual. Svgalib (>;= 1.2.11) 27 July 1997 vga_safety_fork(3)
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