cfspeed.c

用于嵌入式Linux系统的标准C的库函数

/* `struct termios' speed frobnication functions.  Linux version.
   Copyright (C) 1991, 92, 93, 95, 96, 97, 98, 2000 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 by Jeff Johnston, May 27, 2002 to remove kernel hack
   as we simply ignore a cfisetspeed of 0 instead of treating it specially */

#include <stddef.h>
#include <errno.h>
#include <termios.h>

/* Return the output baud rate stored in *TERMIOS_P.  */
speed_t
cfgetospeed (termios_p)
     const struct termios *termios_p;
{
  return termios_p->c_cflag & (CBAUD | CBAUDEX);
}

/* Return the input baud rate stored in *TERMIOS_P.
   For Linux there is no difference between input and output
   speed. */
speed_t
cfgetispeed (termios_p)
     const struct termios *termios_p;
{
  return termios_p->c_cflag & (CBAUD | CBAUDEX);
}

/* Set the output baud rate stored in *TERMIOS_P to SPEED.  */
int
cfsetospeed  (termios_p, speed)
     struct termios *termios_p;
     speed_t speed;
{
  if ((speed & ~CBAUD) != 0
      && (speed < B57600 || speed > __MAX_BAUD))
    {
      errno = (EINVAL);
      return -1;
    }

  termios_p->c_cflag &= ~(CBAUD | CBAUDEX);
  termios_p->c_cflag |= speed;

  return 0;
}

/* Set the input baud rate stored in *TERMIOS_P to SPEED.
   Although for Linux there is no difference between input and output
   speed, the numerical 0 is a special case for the input baud rate.  It
   should set the input baud rate to the output baud rate so we do
   nothing. */
int
cfsetispeed (termios_p, speed)
     struct termios *termios_p;
     speed_t speed;
{
  if ((speed & ~CBAUD) != 0
      && (speed < B57600 || speed > __MAX_BAUD))
    {
      errno = (EINVAL);
      return -1;
    }

  if (speed != 0)
    {
      termios_p->c_cflag &= ~(CBAUD | CBAUDEX);
      termios_p->c_cflag |= speed;
    }

  return 0;
}