rs232_posix.c

/*
 * Copyright (c) 2011 Petr Stetiar <ynezz@true.cz>, Gaben Ltd.
 *
 * Permission is hereby granted, free of charge, to any person
 * obtaining a copy of this software and associated documentation
 * files (the "Software"), to deal in the Software without
 * restriction, including without limitation the rights to use,
 * copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the
 * Software is furnished to do so, subject to the following
 * conditions:
 * 
 * The above copyright notice and this permission notice shall be
 * included in all copies or substantial portions of the Software.
 * 
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
 * OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
 * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
 * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
 * WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
 * OTHER DEALINGS IN THE SOFTWARE.
 *
 */

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <errno.h>
#include <termios.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <sys/time.h>
#include <sys/timeb.h>
#include <sys/ioctl.h>
#include <fcntl.h>
#include <unistd.h>

#include "librs232/rs232.h"

struct rs232_port_t *
rs232_init(void)
{
	struct rs232_port_t *p = NULL;
	p = (struct rs232_port_t *) malloc(sizeof(struct rs232_port_t));
	if (p == NULL)
		return NULL;

	p->pt = (struct rs232_posix_t *) malloc(sizeof(struct rs232_posix_t));
	if (p->pt == NULL)
		return NULL;

	DBG("p=%p p->pt=%p\n", (void *)p, p->pt);

	memset(p->pt, 0, sizeof(struct rs232_posix_t));
	memset(p->dev, 0, RS232_STRLEN_DEVICE+1);
	strncpy(p->dev, RS232_PORT_POSIX, RS232_STRLEN_DEVICE);

	p->baud = RS232_BAUD_115200;
	p->data = RS232_DATA_8;
	p->parity = RS232_PARITY_NONE;
	p->stop = RS232_STOP_1;
	p->flow = RS232_FLOW_OFF;
	p->status = RS232_PORT_CLOSED;
	p->dtr = RS232_DTR_OFF;
	p->rts = RS232_RTS_OFF;

	return p;
}

void
rs232_end(struct rs232_port_t *p)
{
	struct rs232_posix_t *ux = p->pt;

	DBG("p=%p p->pt=%p\n", (void *)p, p->pt);

	if (!rs232_port_open(p)) {
		free(p->pt);
		free(p);
		return;
	}

	rs232_flush(p);

	if (tcsetattr(ux->fd, TCSANOW, &ux->oldterm) < 0) {
		DBG("tcsetattr() %d %s\n", errno, strerror(errno))
		return;
	}

	rs232_close(p);
	free(p->pt);
	free(p);
}

unsigned int
rs232_in_qeue(struct rs232_port_t *p, unsigned int *in_bytes)
{
	fd_set set;
	int ret;
	int b;
	struct timeval tv;
	struct rs232_posix_t *ux = p->pt;

	DBG("p=%p p->pt=%p\n", (void *)p, p->pt);

	if (!rs232_port_open(p))
		return RS232_ERR_PORT_CLOSED;

	FD_ZERO(&set);
	FD_SET(ux->fd, &set);
	/* don't work reliable with 0 */
	tv.tv_usec = 1;
	tv.tv_sec = 0;

	select(ux->fd+1, &set, NULL, NULL, &tv);
	ret = ioctl(ux->fd, FIONREAD, &b);
	if (ret == -1) {
		*in_bytes = 0;
		DBG("%s\n", "RS232_ERR_IOCTL");
		return RS232_ERR_IOCTL;
	}

	*in_bytes = b;
	DBG("in_bytes=%d\n", b);

	return RS232_ERR_NOERROR;
}

/* some USB<->RS232 converters buffer a lot, so this function tries to discard
   this buffer - useful mainly after rs232_open() */
void
rs232_in_qeue_clear(struct rs232_port_t *p)
{
	fd_set set;
	unsigned int ret;
	unsigned int blen;
	unsigned char *buf = NULL;
	struct timeval tv;
	struct rs232_posix_t *ux = p->pt;

	DBG("p=%p p->pt=%p\n", (void *)p, p->pt);

	if (!rs232_port_open(p))
		return;

	rs232_in_qeue(p, &blen);
	if (blen > 0) {
		buf = (unsigned char*) malloc(blen * sizeof(unsigned char*)+1);
		if (buf == NULL)
			return;

		FD_ZERO(&set);
		FD_SET(ux->fd, &set);
		tv.tv_usec = 1;
		tv.tv_sec = 0;

		ret = select(ux->fd+1, &set, NULL, NULL, &tv);
		DBG("select=%d\n", ret);
		if (ret <= 0) {
			free(buf);
			return;
		}

		ret = read(ux->fd, buf, blen);
		DBG("read=%d\n", ret);
		free(buf);
	}
}

unsigned int
rs232_read(struct rs232_port_t *p, unsigned char *buf, unsigned int buf_len,
	   unsigned int *read_len)
{
	int r;
	struct rs232_posix_t *ux = p->pt;

	DBG("p=%p p->pt=%p buf_len=%d\n", (void *)p, p->pt, buf_len);

	if (!rs232_port_open(p))
		return RS232_ERR_PORT_CLOSED;

	r = read(ux->fd, buf, buf_len);
	if (r == -1) {
		*read_len = 0;
		DBG("errno: %d strerror: %s %s\n",
		    errno, strerror(errno), "RS232_ERR_READ");

		return RS232_ERR_READ;
	}

	*read_len = r;
	DBG("read_len=%d hex='%s' ascii='%s'\n", r, rs232_hex_dump(buf, r),
		rs232_ascii_dump(buf, r));

	return RS232_ERR_NOERROR;
}

static int
duration(struct timeval *t1, struct timeval *t2)
{
	return (t2->tv_sec-t1->tv_sec)*1000 + (t2->tv_usec - t1->tv_usec)/1000;
}

/* this function waits either for timeout or buf_len bytes,
   whatever happens first and doesn't return earlier */
unsigned int
rs232_read_timeout_forced(struct rs232_port_t *p, unsigned char *buf,
		   unsigned int buf_len, unsigned int *read_len,
		   unsigned int timeout)
{
	int b;
	int ret;
	int reti;
	fd_set set;
	int r;
	struct rs232_posix_t *ux = p->pt;
	struct timeval tv;
	struct timeval t1;
	struct timeval t2;

	DBG("p=%p p->pt=%p buf_len=%d timeout=%d\n", (void *)p, p->pt, buf_len,
	    timeout);

	if (!rs232_port_open(p))
		return RS232_ERR_PORT_CLOSED;

	FD_ZERO(&set);
	FD_SET(ux->fd, &set);
	tv.tv_sec = (timeout * 1000) / 1000000;
	tv.tv_usec = (timeout * 1000) % 1000000;

	*read_len = 0;
	gettimeofday(&t1, NULL);

	while (1) {
		ret = select(ux->fd+1, &set, NULL, NULL, &tv);
		gettimeofday(&t2, NULL);

		if (ret == 0) {
			DBG("%s\n", "select timeout");
			break;
		}

		if (ret == -1) {
			DBG("%s\n", "select error");
			break;
		}

		if (duration(&t1, &t2) >= (int) timeout) {
			DBG("%s\n", "timeout");
			break;
		}

		reti = ioctl(ux->fd, FIONREAD, &b);
		if (reti == -1) {
			DBG("%s\n", "ioctl error");
			break;
		}

		if ((unsigned int) b >= buf_len) {
			DBG("fionread=%d\n", b);
			break;
		}
	}

	switch (ret) {
	case 0:
		DBG("%s\n", "RS232_ERR_TIMEOUT");
		return RS232_ERR_TIMEOUT;
	case 1:
		r = read(ux->fd, buf, buf_len);
		if (r == -1) {
			DBG("errno: %d strerror: %s %s\n",
			    errno, strerror(errno), "RS232_ERR_READ");

			return RS232_ERR_READ;
		}

		DBG("read_len=%d hex='%s' ascii='%s'\n", r,
			rs232_hex_dump(buf, r),
			rs232_ascii_dump(buf, r));
		*read_len = r;
		break;
	default:
		DBG("%s\n", "RS232_ERR_SELECT");
		return RS232_ERR_SELECT;
	}

	return RS232_ERR_NOERROR;
}

unsigned int
rs232_read_timeout(struct rs232_port_t *p, unsigned char *buf,
		   unsigned int buf_len, unsigned int *read_len,
		   unsigned int timeout)
{
	int ret;
	fd_set set;
	int r;
	struct timeval tv;
	struct rs232_posix_t *ux = p->pt;

	DBG("p=%p p->pt=%p buf_len=%d timeout=%d\n", (void *)p, p->pt,
		buf_len, timeout);

	if (!rs232_port_open(p))
		return RS232_ERR_PORT_CLOSED;

	FD_ZERO(&set);
	FD_SET(ux->fd, &set);
	tv.tv_sec = (timeout * 1000) / 1000000;
	tv.tv_usec = (timeout * 1000) % 1000000;
	*read_len = 0;

	ret = select(ux->fd+1, &set, NULL, NULL, &tv);
	switch (ret) {
	case 0:
		DBG("%s\n", "RS232_ERR_TIMEOUT");
		return RS232_ERR_TIMEOUT;
	case 1:
		r = read(ux->fd, buf, buf_len);
		if (r == -1) {
			DBG("errno: %d strerror: %s %s\n",
			    errno, strerror(errno), "RS232_ERR_READ");
			return RS232_ERR_READ;
		}

		DBG("read_len=%d hex='%s' ascii='%s'\n", r,
			rs232_hex_dump(buf, r),
			rs232_ascii_dump(buf, r));
		*read_len = r;
		break;
	default:
		DBG("%s\n", "RS232_ERR_SELECT");
		return RS232_ERR_SELECT;
	}

	return RS232_ERR_NOERROR;
}

unsigned int
rs232_write(struct rs232_port_t *p, const unsigned char *buf, unsigned int buf_len,
		unsigned int *write_len)
{
	int w;
	struct rs232_posix_t *ux = p->pt;

	DBG("p=%p p->pt=%p hex='%s' ascii='%s' buf_len=%d\n", 
	    (void *)p, p->pt, rs232_hex_dump(buf, buf_len), 
	    rs232_ascii_dump(buf, buf_len), buf_len);

	if (!rs232_port_open(p))
		return RS232_ERR_PORT_CLOSED;

	w = write(ux->fd, buf, buf_len);
	if (w == -1) {
		DBG("errno: %d strerror: %s %s\n",
		    errno, strerror(errno), "RS232_ERR_WRITE");

		*write_len = 0;
		return RS232_ERR_WRITE;
	}

	*write_len = w;
	DBG("write_len=%d hex='%s' ascii='%s'\n", w, rs232_hex_dump(buf, w),
		rs232_ascii_dump(buf, w));

	return RS232_ERR_NOERROR;
}

unsigned int
rs232_write_timeout(struct rs232_port_t *p, const unsigned char *buf,
			unsigned int buf_len, unsigned int *write_len,
			unsigned int timeout)
{
	int ret;
	fd_set set;
	int w;
	struct rs232_posix_t *ux = p->pt;
	struct timeval tv;

	DBG("p=%p p->pt=%p timeout=%d\n", (void *)p, p->pt, timeout);

	if (!rs232_port_open(p))
		return RS232_ERR_PORT_CLOSED;

	FD_ZERO(&set);
	FD_SET(ux->fd, &set);
	tv.tv_sec = (timeout * 1000) / 1000000;
	tv.tv_usec = (timeout * 1000) % 1000000;
	*write_len = 0;

	ret = select(ux->fd+1, NULL, &set, NULL, &tv);
	switch (ret) {
	case 0:
		DBG("%s\n", "RS232_ERR_TIMEOUT");
		return RS232_ERR_TIMEOUT;
	case 1:
		w = write(ux->fd, buf, buf_len);
		if (w == -1) {
			DBG("errno: %d strerror: %s %s\n",
			    errno, strerror(errno), "RS232_ERR_WRITE");

			return RS232_ERR_WRITE;
		}

		*write_len = w;
		DBG("write_len=%d hex='%s' ascii='%s'\n", w,
			rs232_hex_dump(buf, w),
			rs232_ascii_dump(buf, w));
		break;
	default:
		DBG("%s\n", "RS232_ERR_SELECT");
		return RS232_ERR_SELECT;
	}

	return RS232_ERR_NOERROR;
}

unsigned int
rs232_open(struct rs232_port_t *p)
{
	int flags;
	struct termios term;
	struct rs232_posix_t *ux = p->pt;

	DBG("p=%p p->pt=%p\n", (void *)p, p->pt);

	ux->fd = open(p->dev, O_RDWR | O_NOCTTY | O_NDELAY);
	if (ux->fd < 0) {
		DBG("open() %d %s\n", errno, strerror(errno))
		return RS232_ERR_OPEN;
	}

	/* 
	 * On OSX (and maybe on more systems), we need to open() the port with
	 * O_NDELAY, because otherwise it would block forever waiting for DCD
	 * signal, so here we restore back to blocking operations.
	 */
	flags = fcntl(ux->fd, F_GETFL);
	flags &= ~O_NDELAY;
	fcntl(ux->fd, F_SETFL, flags);

	if (tcflush(ux->fd, TCIOFLUSH) < 0) {
		DBG("tcflush() %d %s\n", errno, strerror(errno))
		return RS232_ERR_CONFIG;
	}

	GET_PORT_STATE(ux->fd, &term)
	GET_PORT_STATE(ux->fd, &ux->oldterm)

	term.c_cflag |= (CREAD | CLOCAL);
	term.c_iflag = IGNPAR;
	term.c_oflag = 0;
	term.c_lflag = 0;
	term.c_cc[VINTR]  = _POSIX_VDISABLE;
	term.c_cc[VQUIT]  = _POSIX_VDISABLE;
	term.c_cc[VSTART] = _POSIX_VDISABLE;
	term.c_cc[VSTOP]  = _POSIX_VDISABLE;
	term.c_cc[VSUSP]  = _POSIX_VDISABLE;
	term.c_cc[VEOF]   = _POSIX_VDISABLE;
	term.c_cc[VEOL]   = _POSIX_VDISABLE;
	term.c_cc[VERASE] = _POSIX_VDISABLE;
	term.c_cc[VKILL]  = _POSIX_VDISABLE;

	SET_PORT_STATE(ux->fd, &term)

	rs232_set_baud(p, p->baud);
	rs232_set_data(p, p->data);
	rs232_set_parity(p, p->parity);
	rs232_set_stop(p, p->stop);
	rs232_set_flow(p, p->flow);
	p->status = RS232_PORT_OPEN;

	return RS232_ERR_NOERROR;
}

void
rs232_set_device(struct rs232_port_t *p, const char *device)
{
	DBG("p=%p old=%s new=%s\n", (void *)p, p->dev, device);
	strncpy(p->dev, device, RS232_STRLEN_DEVICE);
	return;
}

unsigned int
rs232_set_baud(struct rs232_port_t *p, enum rs232_baud_e baud)
{
	struct termios term;
	struct rs232_posix_t *ux = p->pt;

	DBG("p=%p p->pt=%p baud=%d (%s bauds)\n",
	    (void *)p, p->pt, baud, rs232_strbaud(baud));

	if (!rs232_port_open(p))
		return RS232_ERR_PORT_CLOSED;

	GET_PORT_STATE(ux->fd, &term)

	switch (baud) {
	case RS232_BAUD_300:
		cfsetispeed(&term, B300);
		cfsetospeed(&term, B300);
		break;
	case RS232_BAUD_2400:
		cfsetispeed(&term, B2400);
		cfsetospeed(&term, B2400);
		break;
	case RS232_BAUD_4800:
		cfsetispeed(&term, B4800);
		cfsetospeed(&term, B4800);
		break;
	case RS232_BAUD_9600:
		cfsetispeed(&term, B9600);
		cfsetospeed(&term, B9600);
		break;
	case RS232_BAUD_19200:
		cfsetispeed(&term, B19200);
		cfsetospeed(&term, B19200);
		break;
	case RS232_BAUD_38400:
		cfsetispeed(&term, B38400);
		cfsetospeed(&term, B38400);
		break;
	case RS232_BAUD_57600:
		cfsetispeed(&term, B57600);
		cfsetospeed(&term, B57600);
		break;
	case RS232_BAUD_115200:
		cfsetispeed(&term, B115200);
		cfsetospeed(&term, B115200);
		break;
	case RS232_BAUD_460800:
		cfsetispeed(&term, B460800);
		cfsetospeed(&term, B460800);
		break;
	default:
		return RS232_ERR_UNKNOWN;
	}

	SET_PORT_STATE(ux->fd, &term)
	p->baud = baud;

	return RS232_ERR_NOERROR;
}

unsigned int
rs232_set_dtr(struct rs232_port_t *p, enum rs232_dtr_e state)
{
	int ret;
	int set;
	struct rs232_posix_t *ux = p->pt;

	DBG("p=%p p->pt=%p dtr=%d (dtr control %s)\n",
	    (void *)p, p->pt, state, rs232_strdtr(state));

	if (!rs232_port_open(p))
		return RS232_ERR_PORT_CLOSED;

	ret = ioctl(ux->fd, TIOCMGET, &set);
	if (ret == -1) {
		DBG("%s\n", "TIOCMGET RS232_ERR_IOCTL");
		return RS232_ERR_IOCTL;
	}

	switch (state) {
	case RS232_DTR_OFF:
		set &= ~TIOCM_DTR;
		break;
	case RS232_DTR_ON:
		set |= TIOCM_DTR;
		break;
	default:
		return RS232_ERR_UNKNOWN;
	}

	ret = ioctl(ux->fd, TIOCMSET, &set);
	if (ret == -1) {
		DBG("%s\n", "TIOCMSET RS232_ERR_IOCTL");
		return RS232_ERR_IOCTL;
	}
	
	p->dtr = state;

	return RS232_ERR_NOERROR;
}

unsigned int
rs232_set_rts(struct rs232_port_t *p, enum rs232_rts_e state)
{
	int ret;
	int set;
	struct rs232_posix_t *ux = p->pt;

	DBG("p=%p p->pt=%p rts=%d (rts control %s)\n",
	    (void *)p, p->pt, state, rs232_strrts(state));

	if (!rs232_port_open(p))
		return RS232_ERR_PORT_CLOSED;

	ret = ioctl(ux->fd, TIOCMGET, &set);
	if (ret == -1) {
		DBG("%s\n", "TIOCMGET RS232_ERR_IOCTL");
		return RS232_ERR_IOCTL;
	}

	switch (state) {
	case RS232_RTS_OFF:
		set &= ~TIOCM_RTS;
		break;
	case RS232_RTS_ON:
		set |= TIOCM_RTS;
		break;
	default:
		return RS232_ERR_UNKNOWN;
	}

	ret = ioctl(ux->fd, TIOCMSET, &set);
	if (ret == -1) {
		DBG("%s\n", "TIOCMSET RS232_ERR_IOCTL");
		return RS232_ERR_IOCTL;
	}
	
	p->rts = state;

	return RS232_ERR_NOERROR;
}

unsigned int
rs232_set_parity(struct rs232_port_t *p, enum rs232_parity_e parity)
{
	struct termios term;
	struct rs232_posix_t *ux = p->pt;

	DBG("p=%p p->pt=%p parity=%d (parity %s)\n",
	    (void *)p, p->pt, parity, rs232_strparity(parity));

	if (!rs232_port_open(p))
		return RS232_ERR_PORT_CLOSED;

	GET_PORT_STATE(ux->fd, &term)

	switch (parity) {
	case RS232_PARITY_NONE:
		term.c_cflag &= ~PARENB;
		break;
	case RS232_PARITY_ODD:
		term.c_cflag |= (PARENB | PARODD);
		break;
	case RS232_PARITY_EVEN:
		term.c_cflag &= ~PARODD;
		term.c_cflag |= PARENB;
		break;
	default:
		return RS232_ERR_UNKNOWN;
	}

	SET_PORT_STATE(ux->fd, &term)
	p->parity = parity;

	return RS232_ERR_NOERROR;
}

unsigned int
rs232_set_stop(struct rs232_port_t *p, enum rs232_stop_e stop)
{
	struct termios term;
	struct rs232_posix_t *ux = p->pt;

	DBG("p=%p p->pt=%p stop=%d (%s stop bits)\n",
	    (void *)p, p->pt, stop, rs232_strstop(stop));

	if (!rs232_port_open(p))
		return RS232_ERR_PORT_CLOSED;

	GET_PORT_STATE(ux->fd, &term)
	term.c_cflag &= ~CSTOPB;

	switch (stop) {
	case RS232_STOP_1:
		break;
	case RS232_STOP_2:
		term.c_cflag |= CSTOPB;
		break;
	default:
		return RS232_ERR_UNKNOWN;
	}

	SET_PORT_STATE(ux->fd, &term)
	p->stop = stop;

	return RS232_ERR_NOERROR;
}

unsigned int
rs232_set_data(struct rs232_port_t *p, enum rs232_data_e data)
{
	struct termios term;
	struct rs232_posix_t *ux = p->pt;

	DBG("p=%p p->pt=%p data=%d (%s data bits)\n",
	    (void *)p, p->pt, data, rs232_strdata(data));

	if (!rs232_port_open(p))
		return RS232_ERR_PORT_CLOSED;

	GET_PORT_STATE(ux->fd, &term)
	term.c_cflag &= ~CSIZE;

	switch (data) {
	case RS232_DATA_5:
		term.c_cflag |= CS5;
		break;
	case RS232_DATA_6:
		term.c_cflag |= CS6;
		break;
	case RS232_DATA_7:
		term.c_cflag |= CS7;
		break;
	case RS232_DATA_8:
		term.c_cflag |= CS8;
		break;
	default:
		return RS232_ERR_UNKNOWN;
	}

	SET_PORT_STATE(ux->fd, &term)
	p->data = data;

	return RS232_ERR_NOERROR;
}

unsigned int
rs232_set_flow(struct rs232_port_t *p, enum rs232_flow_e flow)
{
	struct termios term;
	struct rs232_posix_t *ux = p->pt;

	DBG("p=%p p->pt=%p flow=%d (flow control %s)\n",
	    (void *)p, p->pt, flow, rs232_strflow(flow));

	if (!rs232_port_open(p))
		return RS232_ERR_PORT_CLOSED;

	GET_PORT_STATE(ux->fd, &term)

	switch (flow) {
	case RS232_FLOW_OFF:
		term.c_cflag &= ~CRTSCTS;
		term.c_iflag &= ~(IXON | IXOFF | IXANY);
		break;
	case RS232_FLOW_HW:
		term.c_cflag |= CRTSCTS;
		term.c_iflag &= ~(IXON | IXOFF | IXANY);
		break;
	case RS232_FLOW_XON_XOFF:
		term.c_cflag &= ~CRTSCTS;
		term.c_iflag |= (IXON | IXOFF | IXANY);
		break;
	default:
		return RS232_ERR_UNKNOWN;
	}

	SET_PORT_STATE(ux->fd, &term)
	p->flow = flow;

	return RS232_ERR_NOERROR;
}

unsigned int
rs232_flush(struct rs232_port_t *p)
{
	int ret;
	struct rs232_posix_t *ux = p->pt;

	DBG("p=%p p->pt=%p\n", (void *)p, p->pt);

	if (!rs232_port_open(p))
		return RS232_ERR_PORT_CLOSED;

	ret = tcflush(ux->fd, TCIOFLUSH);
	if (ret == -1)
		return RS232_ERR_FLUSH;

	return RS232_ERR_NOERROR;
}

unsigned int
rs232_close(struct rs232_port_t *p)
{
	int ret;
	struct rs232_posix_t *ux = p->pt;

	DBG("p=%p p->pt=%p\n", (void *)p, p->pt);

	if (!rs232_port_open(p))
		return RS232_ERR_PORT_CLOSED;

	ret = close(ux->fd);
	if (ret == -1)
		return RS232_ERR_CLOSE;

	p->status = RS232_PORT_CLOSED;
	return RS232_ERR_NOERROR;
}

unsigned int
rs232_fd(struct rs232_port_t *p)
{
	struct rs232_posix_t *ux = p->pt;

	DBG("p=%p p->pt=%p ux->fd=%d\n", (void *)p, p->pt, ux->fd);

	return (unsigned int) ux->fd;
}