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  corresponding  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 corresponding 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)