speed.c

来自「一个C源代码分析器」· C语言 代码 · 共 114 行

/* `struct termios' speed frobnication functions.  SunOS 4 version.
Copyright (C) 1991, 1992, 1993 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 Library General Public License as
published by the Free Software Foundation; either version 2 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
Library General Public License for more details.

You should have received a copy of the GNU Library General Public
License along with the GNU C Library; see the file COPYING.LIB.  If
not, write to the Free Software Foundation, Inc., 675 Mass Ave,
Cambridge, MA 02139, USA.  */

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

static CONST speed_t speeds[] =
  {
    0,
    50,
    75,
    110,
    134,
    150,
    200,
    300,
    600,
    1200,
    1800,
    2400,
    4800,
    9600,
    19200,
    38400,
  };


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

/* Return the input baud rate stored in *TERMIOS_P.  */
speed_t
DEFUN(cfgetispeed, (termios_p), CONST struct termios *termios_p)
{
  return (termios_p->c_cflag & CIBAUD) >> IBSHIFT;
}

/* Set the output baud rate stored in *TERMIOS_P to SPEED.  */
int
DEFUN(cfsetospeed, (termios_p, speed),
      struct termios *termios_p AND speed_t speed)
{
  register unsigned int i;

  if (termios_p == NULL)
    {
      errno = EINVAL;
      return -1;
    }

  /* This allows either B1200 or 1200 to work.	XXX
     Do we really want to try to support this, given that
     fetching the speed must return one or the other?  */

  for (i = 0; i < sizeof (speeds) / sizeof (speeds[0]); ++i)
    if (i == speed || speeds[i] == speed)
      {
	termios_p->c_cflag &= ~CBAUD;
	termios_p->c_cflag |= i;
	return 0;
      }

  errno = EINVAL;
  return -1;
}

/* Set the input baud rate stored in *TERMIOS_P to SPEED.  */
int
DEFUN(cfsetispeed, (termios_p, speed),
      struct termios *termios_p AND speed_t speed)
{
  register unsigned int i;

  if (termios_p == NULL)
    {
      errno = EINVAL;
      return -1;
    }

  /* See comment in cfsetospeed (above).  */
  for (i = 0; i < sizeof (speeds) / sizeof (speeds[0]); ++i)
    if (i == speed || speeds[i] == speed)
      {
	termios_p->c_cflag &= ~CIBAUD;
	termios_p->c_cflag |= i << IBSHIFT;
	return 0;
      }

  errno = EINVAL;
  return -1;
}