picocom/termios2.c

/*
 * termios2.c
 *
 * Use termios2 interface to set custom baud rates to serial ports.
 *
 * by Nick Patavalis (npat@efault.net)
 *
 * ATTENTION: Very linux-specific kludge! 
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License as
 * published by the Free Software Foundation; either version 2 of the
 * License, or (at your option) any later version.
 *
 * This program 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
 * General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307
 * USA 
 */

#ifndef __linux__
#error "Linux specific code!"
#endif /* of __linux__ */

#include <stdio.h>
#include <string.h>
#include <unistd.h>
#include <errno.h>
#include <termios.h>
#include <sys/ioctl.h>

/* Contains the definition of the termios2 structure and some
   associated constants that we should normally include from kernel
   sources. But unfortunatelly, we can't. See comments in
   "termbits2.h" for more. */
#include "termbits2.h"

/* GLIBC termios use an (otherwise unused) bit in c_iflags to
   internally record the fact that ispeed was set to zero (which is
   special behavior and means "same as ospeed". We want to clear this
   bit before passing c_iflags back to the kernel. See: 
  
       <glibc-source>/sysdeps/unix/sysv/linux/speed.c 
*/
#define IBAUD0 020000000000

int
tc2setattr(int fd, int optional_actions, const struct termios *tios)
{
	struct termios2 t2;
	int cmd;

	switch (optional_actions) {
	case TCSANOW:
		cmd = TCSETS2;
		break;
	case TCSADRAIN:
		cmd = TCSETSW2;
		break;
	case TCSAFLUSH:
		cmd = TCSETSF2;
		break;
	default:
		errno = EINVAL;
		return -1;
	}

	t2.c_iflag = tios->c_iflag & ~IBAUD0;
	t2.c_oflag = tios->c_oflag;
	t2.c_cflag = tios->c_cflag;
	t2.c_lflag = tios->c_lflag;
	t2.c_line = tios->c_line;
	t2.c_ispeed = tios->c_ispeed;
	t2.c_ospeed = tios->c_ospeed;
	memcpy(&t2.c_cc[0], &tios->c_cc[0], K_NCCS * sizeof (cc_t));
	
	return ioctl(fd, cmd, &t2);
}

int
tc2getattr(int fd, struct termios *tios)
{
	struct termios2 t2;
	size_t i;
	int r;

	r = ioctl(fd, TCGETS2, &t2);
	if (r < 0) return r;

	tios->c_iflag = t2.c_iflag;
	tios->c_oflag = t2.c_oflag;
	tios->c_cflag = t2.c_cflag;
	tios->c_lflag = t2.c_lflag;
	tios->c_line = t2.c_line;
	tios->c_ispeed = t2.c_ispeed;
	tios->c_ospeed = t2.c_ospeed;
	memcpy(&tios->c_cc[0], &t2.c_cc[0], K_NCCS * sizeof (cc_t));
	
	for (i = K_NCCS; i < NCCS; i++)
		tios->c_cc[i] = _POSIX_VDISABLE;

	return 0;
}

/* The termios2 interface supports separate input and output
   speeds. Old termios supported only one terminal speed. So the
   standard tcsetispeed(3), actually sets the output-speed field, not
   the input-speed field (or does nothing if speed == B0). Use
   tc2setispeed if you want to set a standard input speed (one of the
   Bxxxxx speeds) that may be different from the output speed. Also if
   someone, somehow, has set the input speed to something other than
   B0, then you *must* use c2setispeed() to change it. Using the
   standard cfsetispeed() obviously won't do (since it affects only
   the output-speed field).
*/

int
cf2setispeed(struct termios *tios, speed_t speed)
{
	if ( (speed & ~CBAUD) != 0 
		 && (speed < B57600 || speed > __MAX_BAUD) ) {
		errno = EINVAL;
		return -1;
	}
	tios->c_ispeed = speed;
	tios->c_cflag &= ~((CBAUD | CBAUDEX) << IBSHIFT);
	tios->c_cflag |= (speed << IBSHIFT);

	return 0;
}

speed_t
cf2getispeed(struct termios *tios)
{
	return (tios->c_cflag >> IBSHIFT) & (CBAUD | CBAUDEX);
}

int
cf2setospeed_custom(struct termios *tios, int speed)
{
	if ( speed <= 0 ) {
		errno = EINVAL;
		return -1;
	}		
	tios->c_cflag = (tios->c_cflag & ~CBAUD) | BOTHER;
	tios->c_ospeed = speed;

	return 0;
}

int
cf2setispeed_custom(struct termios *tios, int speed)
{
	if ( speed < 0 ) {
		errno = EINVAL;
		return -1;
	}
	if ( speed == 0 ) {
		/* Special case: ispeed == 0 means "same as ospeed". Kernel
		 * does this if it sees B0 in the "CIBAUD" field (i.e. in
		 * CBAUD << IBSHIFT) */
		tios->c_cflag = 
			(tios->c_cflag & ~(CBAUD << IBSHIFT)) | (B0 << IBSHIFT);
	} else {
		tios->c_cflag = 
			(tios->c_cflag & ~(CBAUD << IBSHIFT)) | (BOTHER << IBSHIFT);
		tios->c_ispeed = speed;
	}

	return 0;
}

/***************************************************************************/

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