sysdeps/unix/sysv/linux/speed.c

   1 /* `struct termios' speed frobnication functions.  Linux version.
   2    Copyright (C) 1991,1992,1993,1995,1996,1997,1998,2000,2002,2003
   3         Free Software Foundation, Inc.
   4    This file is part of the GNU C Library.
   5
   6    The GNU C Library is free software; you can redistribute it and/or
   7    modify it under the terms of the GNU Lesser General Public
   8    License as published by the Free Software Foundation; either
   9    version 2.1 of the License, or (at your option) any later version.
  10
  11    The GNU C Library is distributed in the hope that it will be useful,
  12    but WITHOUT ANY WARRANTY; without even the implied warranty of
  13    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14    Lesser General Public License for more details.
  15
  16    You should have received a copy of the GNU Lesser General Public
  17    License along with the GNU C Library; if not, write to the Free
  18    Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
  19    02111-1307 USA.  */
  20
  21 #include <stddef.h>
  22 #include <errno.h>
  23 #include <termios.h>
  24
  25
  26 /* This is a gross hack around a kernel bug.  If the cfsetispeed functions
  27    is called with the SPEED argument set to zero this means use the same
  28    speed as for output.  But we don't have independent input and output
  29    speeds and therefore cannot record this.
  30
  31    We use an unused bit in the `c_iflag' field to keep track of this
  32    use of `cfsetispeed'.  The value here must correspond to the one used
  33    in `tcsetattr.c'.  */
  34 #define IBAUD0  020000000000
  35
  36
  37 /* Return the output baud rate stored in *TERMIOS_P.  */
  38 speed_t
  39 cfgetospeed (termios_p)
  40      const struct termios *termios_p;
  41 {
  42   return termios_p->c_cflag & (CBAUD | CBAUDEX);
  43 }
  44
  45 /* Return the input baud rate stored in *TERMIOS_P.
  46    Although for Linux there is no difference between input and output
  47    speed, the numerical 0 is a special case for the input baud rate. It
  48    should set the input baud rate to the output baud rate. */
  49 speed_t
  50 cfgetispeed (termios_p)
  51      const struct termios *termios_p;
  52 {
  53   return ((termios_p->c_iflag & IBAUD0)
  54           ? 0 : termios_p->c_cflag & (CBAUD | CBAUDEX));
  55 }
  56
  57 /* Set the output baud rate stored in *TERMIOS_P to SPEED.  */
  58 int
  59 cfsetospeed  (termios_p, speed)
  60      struct termios *termios_p;
  61      speed_t speed;
  62 {
  63   if ((speed & ~CBAUD) != 0
  64       && (speed < B57600 || speed > __MAX_BAUD))
  65     {
  66       __set_errno (EINVAL);
  67       return -1;
  68     }
  69
  70 #ifdef _HAVE_STRUCT_TERMIOS_C_OSPEED
  71   termios_p->c_ospeed = speed;
  72 #endif
  73   termios_p->c_cflag &= ~(CBAUD | CBAUDEX);
  74   termios_p->c_cflag |= speed;
  75
  76   return 0;
  77 }
  78 libc_hidden_def (cfsetospeed)
  79
  80
  81 /* Set the input baud rate stored in *TERMIOS_P to SPEED.
  82    Although for Linux there is no difference between input and output
  83    speed, the numerical 0 is a special case for the input baud rate.  It
  84    should set the input baud rate to the output baud rate.  */
  85 int
  86 cfsetispeed (termios_p, speed)
  87      struct termios *termios_p;
  88      speed_t speed;
  89 {
  90   if ((speed & ~CBAUD) != 0
  91       && (speed < B57600 || speed > __MAX_BAUD))
  92     {
  93       __set_errno (EINVAL);
  94       return -1;
  95     }
  96
  97 #ifdef _HAVE_STRUCT_TERMIOS_C_ISPEED
  98   termios_p->c_ispeed = speed;
  99 #endif
 100   if (speed == 0)
 101     termios_p->c_iflag |= IBAUD0;
 102   else
 103     {
 104       termios_p->c_iflag &= ~IBAUD0;
 105       termios_p->c_cflag &= ~(CBAUD | CBAUDEX);
 106       termios_p->c_cflag |= speed;
 107     }
 108
 109   return 0;
 110 }
 111 libc_hidden_def (cfsetispeed)