tcsendbrk.c

用于嵌入式Linux系统的标准C的库函数

/* Copyright (C) 1992, 1996, 1997 Free Software Foundation, Inc.
   This file is part of the GNU C Library.

   The GNU C Library is free software; you can redistribute it and/or
   modify it under the terms of the GNU Lesser General Public
   License as published by the Free Software Foundation; either
   version 2.1 of the License, or (at your option) any later version.

   The GNU C Library is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
   Lesser General Public License for more details.

   You should have received a copy of the GNU Lesser General Public
   License along with the GNU C Library; if not, write to the Free
   Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
   02111-1307 USA.  */

/* Modified for newlib, May 27, 2002, by Jeff Johnston */

#include <errno.h>
#include <stddef.h>
#include <signal.h>
#include <termios.h>
#include <unistd.h>
#include <sys/ioctl.h>

/* Send zero bits on FD.  */
int
tcsendbreak (fd, duration)
     int fd;
     int duration;
{
  /* The break lasts 0.25 to 0.5 seconds if DURATION is zero,
     and an implementation-defined period if DURATION is nonzero.
     We define a positive DURATION to be number of milliseconds to break.  */
  if (duration <= 0)
    return ioctl (fd, TCSBRK, 0);

  /* ioctl can't send a break of any other duration for us.
     This could be changed to use trickery (e.g. lower speed and
     send a '\0') to send the break, but for now just return an error.  */
  errno = (EINVAL);
  return -1;
}