select function

[Joel Sherrill]

Mark Mussetter wrote:

> Hello Everyone,
> 
> I'm working on a project that is based on a motorola 5272 running 
> RTEMS.  I'm also using fltk1.1.4, nxlib, and microwindows in the project.

I cc'ed Rosimildo hoping he remembers his solution to this
way back when.  An archive of his site is in the 4.6.0/contrib
directory so you could peek there and see what he did to solve this.


> I'm getting an undefined reference to 'select' error when I build my 
> project.  In a fltk file called Fl_x.cxx, the function fl_wait() 
> references two functions called select() and poll().

RTEMS does not currently upport select() on ttys and does not have
poll() unless someone slipped one in on me.


> The following is a clip from the fl_wait() function:
> 
> <SNIP>
> #  if USE_POLL
>     n = ::poll(pollfds, nfds, int(time_to_wait*1000 + .5));
> #  else
>     timeval t;
>     t.tv_sec = int(time_to_wait);
>     t.tv_usec = int(1000000 * (time_to_wait-t.tv_sec));
>     n = ::select(maxfd+1,&fdt[0],&fdt[1],&fdt[2],&t);
> #  endif
> <END SNIP>
> 
> Here's my question:  Is there an RTEMS equivalent of one of these 
> functions?
> 
> Currently I can get the project to build by adding conditionals that 
> just make the function return, but I doubt that this will be a valid 
> solution.

It won't work. :)

Eric Norum has a long term solution in mind but a shorter term
solution might be just to be able to register a callback
for logical events in the termios code.  Then select could
register for certain events in the various ttys.  This would
have to be integrated with the socket only select RTEMS has
now.

> 
> Any help on this matter would be greatly appreciated.
> 
> Thanks,
> 
> Mark Mussetter
> Link Communications, Inc.
> email: <mailto:mark at link-comm.com>mark at link-comm.com
> 
> 
> The entire fl_wait() function follows:
> <SNIP>
> // This is never called with time_to_wait < 0.0:
> // It should return negative on error, 0 if nothing happens before
> // timeout, and >0 if any callbacks were done.
> int fl_wait(double time_to_wait) {
> 
>   // OpenGL and other broken libraries call XEventsQueued
>   // unnecessarily and thus cause the file descriptor to not be ready,
>   // so we must check for already-read events:
>   if (fl_display && XQLength(fl_display)) {do_queued_events(); return 1;}
> 
> #  if !USE_POLL
>   fd_set fdt[3];
>   fdt[0] = fdsets[0];
>   fdt[1] = fdsets[1];
>   fdt[2] = fdsets[2];
> #  endif
>   int n;
> 
>   fl_unlock_function();
> 
>   if (time_to_wait < 2147483.648) {
> #  if USE_POLL
>     n = ::poll(pollfds, nfds, int(time_to_wait*1000 + .5));
> #  else
>     timeval t;
>     t.tv_sec = int(time_to_wait);
>     t.tv_usec = int(1000000 * (time_to_wait-t.tv_sec));
>     n = ::select(maxfd+1,&fdt[0],&fdt[1],&fdt[2],&t);
> #  endif
>   } else {
> #  if USE_POLL
>     n = ::poll(pollfds, nfds, -1);
> #  else
>     n = ::select(maxfd+1,&fdt[0],&fdt[1],&fdt[2],0);
> #  endif
>   }
> 
>   fl_lock_function();
> 
>   if (n > 0) {
>     for (int i=0; i<nfds; i++) {
> #  if USE_POLL
>       if (pollfds[i].revents) fd[i].cb(pollfds[i].fd, fd[i].arg);
> #  else
>       int f = fd[i].fd;
>       short revents = 0;
>       if (FD_ISSET(f,&fdt[0])) revents |= POLLIN;
>       if (FD_ISSET(f,&fdt[1])) revents |= POLLOUT;
>       if (FD_ISSET(f,&fdt[2])) revents |= POLLERR;
>       if (fd[i].events & revents) fd[i].cb(f, fd[i].arg);
> #  endif
>     }
>   }
>   return n;
> }
> <END SNIP>
>