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glibc  2.9
tcsendbrk.c
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00001 /* Send break to terminal.
00002    Copyright (C) 1996, 1997 Free Software Foundation, Inc.
00003    This file is part of the GNU C Library.
00004 
00005    The GNU C Library is free software; you can redistribute it and/or
00006    modify it under the terms of the GNU Lesser General Public
00007    License as published by the Free Software Foundation; either
00008    version 2.1 of the License, or (at your option) any later version.
00009 
00010    The GNU C Library is distributed in the hope that it will be useful,
00011    but WITHOUT ANY WARRANTY; without even the implied warranty of
00012    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
00013    Lesser General Public License for more details.
00014 
00015    You should have received a copy of the GNU Lesser General Public
00016    License along with the GNU C Library; if not, write to the Free
00017    Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
00018    02111-1307 USA.  */
00019 
00020 #include <errno.h>
00021 #include <stddef.h>
00022 #include <termios.h>
00023 #include <sys/ioctl.h>
00024 
00025 /* Send zero bits on FD.  */
00026 int
00027 tcsendbreak (int fd, int duration)
00028 {
00029   /* The break lasts 0.25 to 0.5 seconds if DURATION is zero,
00030      and an implementation-defined period if DURATION is nonzero.
00031      We define a positive DURATION to be number of milliseconds to break.  */
00032   if (duration <= 0)
00033     return __ioctl (fd, TCSBRK, 0);
00034 
00035 #ifdef TCSBRKP
00036   /* Probably Linux-specific: a positive third TCSBRKP ioctl argument is
00037      defined to be the number of 100ms units to break.  */
00038   return __ioctl (fd, TCSBRKP, (duration + 99) / 100);
00039 #else
00040   /* ioctl can't send a break of any other duration for us.
00041      This could be changed to use trickery (e.g. lower speed and
00042      send a '\0') to send the break, but for now just return an error.  */
00043   __set_errno (EINVAL);
00044   return -1;
00045 #endif
00046 }