sysdeps/unix/bsd/tcsendbrk.c

   1 /* Copyright (C) 1991, 1992, 1997 Free Software Foundation, Inc.
   2    This file is part of the GNU C Library.
   3
   4    The GNU C Library is free software; you can redistribute it and/or
   5    modify it under the terms of the GNU Library General Public License as
   6    published by the Free Software Foundation; either version 2 of the
   7    License, or (at your option) any later version.
   8
   9    The GNU C Library is distributed in the hope that it will be useful,
  10    but WITHOUT ANY WARRANTY; without even the implied warranty of
  11    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  12    Library General Public License for more details.
  13
  14    You should have received a copy of the GNU Library General Public
  15    License along with the GNU C Library; see the file COPYING.LIB.  If not,
  16    write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  17    Boston, MA 02111-1307, USA.  */
  18
  19 #include <errno.h>
  20 #include <stddef.h>
  21 #include <signal.h>
  22 #include <termios.h>
  23 #include <unistd.h>
  24 #include "bsdtty.h"
  25 #include <sys/file.h>
  26 #include <sys/time.h>
  27 #include <sys/types.h>
  28
  29 /* Send zero bits on FD.  */
  30 int
  31 tcsendbreak (fd, duration)
  32      int fd;
  33      int duration;
  34 {
  35   struct timeval delay;
  36
  37   /* The break lasts 0.25 to 0.5 seconds if DURATION is zero,
  38      and an implementation-defined period if DURATION is nonzero.
  39      We define a positive DURATION to be number of microseconds to break.  */
  40   if (duration <= 0)
  41     duration = 400000;
  42
  43   delay.tv_sec = 0;
  44   delay.tv_usec = duration;
  45
  46   /* Starting sending break.  */
  47   if (__ioctl (fd, TIOCSBRK, (PTR) NULL) < 0)
  48     return -1;
  49
  50   /* Wait DURATION microseconds.  */
  51   (void) __select (0, (fd_set *) NULL, (fd_set *) NULL, (fd_set *) NULL,
  52                    &delay);
  53
  54   /* Turn off the break.  */
  55   return __ioctl (fd, TIOCCBRK, (PTR) NULL);
  56 }