vga_waitevent(3)						Svgalib User Manual						  vga_waitevent(3)

NAME

       vga_waitevent - wait for various I/O events

SYNOPSIS

       #include <sys/time.h>
       #include <sys/types.h>
       #include <unistd.h>
       #include <vga.h>

       int vga_waitevent(int which, fd_set *input, fd_set *output , fd_set *except, struct timeval *timeout)

DESCRIPTION

       This  is  the  only function allowing you to wait for keyboard AND mouse events. It is based on the select(2) library function, so for deep
       understanding of vga_waitevent() look at select(2) as well.

       which can be 0 or logical ored together from VGA_MOUSEEVENT and VGA_KEYEVENT.  If you are interested in waiting for file descriptors having
       input available or being ready for new write data or being in an exceptional condition (urgent data arrived on a TCP stream) set the corre-
       sponding bits in the fd_set structures passed (see select(3)).  If you want vga_waitevent() to return after a timeout value pass  a  struct
       timeval with the desired value. If you are not interested in the corresponding events you may pass NULL for any of the pointers.

       If NULL is passed for timeout vga_waitevent() will not time out but block until any of the other events occurs.	If the integer returned is
       < 0 an error occurred. Check the global variable errno for details. If a value  >=  0  is  returned  it	is  a  bitmask	constructed  using
       VGA_MOUSEEVENT and VGA_KEYEVENT to show which of these events occured.

       If  any of these two occured the appropriate update functions are already called by vga_waitevent().vga_waitevent() operates in raw as well
       as non-raw keyboard mode. In the latter case use vga_getch(3) not vga_getkey(3) to read the newly arrived keys.

       Any of the file related conditions being met will be signalled by setting exactly the bits for files that met the conditions in the  corre-
       sponding fd_set structures. If a non-NULL timeout is passed the remaining time is written into it on return.  If it is 0 a timeout occured.
       (again: cf.  select(2)) Therefore, depending on context, vga_waitkey(3) may return 0 if only special, non svgalib, events occured.

EXAMPLES

       If you want to wait blocking for a keypress OR a mouse event use: vga_waitevent(VGA_MOUSEEVENT | VGA_KEYEVENT, NULL, NULL, NULL, NULL);

       If you want to wait for a keypress OR a mouse event but non-blocking use:

       #include <sys/time.h>
       #include <sys/types.h>
       #include <unistd.h>
       #include <vga.h>

       struct timeval timeout;
       timeout.tv_sec = 0;
       timeout.tv_usec = 0;
       vga_waitevent(VGA_MOUSEEVENT | VGA_KEYEVENT, NULL, NULL, NULL, &timeout);

       You could do a similar thing by just calling

       mouse_update();
       keyboard_update();

       though. There is no such counterpart for the first example.

       Finally, there is a very nice eventtest(6) demo showing most capabilities of vga_waitevent().

BUGS

       This function was introduced in 1.2.10. Unfortunately there was a typo in the first implementation which broke the  case  where	input  was
       NULL.  Though fixed in 1.2.11 for optimal portability pass an empty fd_set instead of NULL as first argument.

       When  not  running  in  background mode, that is, the svgalib applcation is suspended while the VC is switched away, it seems vga_waitevent
       gets stuck and does no longer timeout. It is not clear if this is an svgalib bug, kernel bug or general problem.

SEE ALSO

       svgalib(7), vgagl(7), libvga.config(5),	eventtest(6),  mouse_getposition_6d(3),  mouse_getx(3),  mouse_update(3),  mouse_waitforupdate(3),
       vga_getkey(3), vga_getch(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_waitevent(3)