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.