xref: /netbsd-src/external/bsd/ntp/dist/parseutil/dcfd.c (revision eabc0478de71e4e011a5b4e0392741e01d491794)

/*	$NetBSD: dcfd.c,v 1.7 2024/08/18 20:47:19 christos Exp $	*/

/*
 * /src/NTP/REPOSITORY/ntp4-dev/parseutil/dcfd.c,v 4.18 2005/10/07 22:08:18 kardel RELEASE_20051008_A
 *
 * dcfd.c,v 4.18 2005/10/07 22:08:18 kardel RELEASE_20051008_A
 *
 * DCF77 100/200ms pulse synchronisation daemon program (via 50Baud serial line)
 *
 * Features:
 *  DCF77 decoding
 *  simple NTP loopfilter logic for local clock
 *  interactive display for debugging
 *
 * Lacks:
 *  Leap second handling (at that level you should switch to NTP Version 4 - really!)
 *
 * Copyright (c) 1995-2015 by Frank Kardel <kardel <AT> ntp.org>
 * Copyright (c) 1989-1994 by Frank Kardel, Friedrich-Alexander Universitaet Erlangen-Nuernberg, Germany
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. Neither the name of the author nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 *
 */

#ifdef HAVE_CONFIG_H
# include <config.h>
#endif

#include <sys/ioctl.h>
#include <unistd.h>
#include <stdio.h>
#include <fcntl.h>
#include <sys/types.h>
#include <sys/time.h>
#include <signal.h>
#include <syslog.h>
#include <time.h>

/*
 * NTP compilation environment
 */
#include "ntp_stdlib.h"
#include "ntpd.h"   /* indirectly include ntp.h to get YEAR_PIVOT   Y2KFixes */

/*
 * select which terminal handling to use (currently only SysV variants)
 */
#if defined(HAVE_TERMIOS_H) || defined(STREAM)
#include <termios.h>
#define TTY_GETATTR(_FD_, _ARG_) tcgetattr((_FD_), (_ARG_))
#define TTY_SETATTR(_FD_, _ARG_) tcsetattr((_FD_), TCSANOW, (_ARG_))
#else  /* not HAVE_TERMIOS_H || STREAM */
# if defined(HAVE_TERMIO_H) || defined(HAVE_SYSV_TTYS)
#  include <termio.h>
#  define TTY_GETATTR(_FD_, _ARG_) ioctl((_FD_), TCGETA, (_ARG_))
#  define TTY_SETATTR(_FD_, _ARG_) ioctl((_FD_), TCSETAW, (_ARG_))
# endif/* HAVE_TERMIO_H || HAVE_SYSV_TTYS */
#endif /* not HAVE_TERMIOS_H || STREAM */


#ifndef TTY_GETATTR
#include "Bletch: MUST DEFINE ONE OF 'HAVE_TERMIOS_H' or 'HAVE_TERMIO_H'"
#endif

#ifndef days_per_year
#define days_per_year(_x_) (((_x_) % 4) ? 365 : (((_x_) % 400) ? 365 : 366))
#endif

#define timernormalize(_a_) \
	if ((_a_)->tv_usec >= 1000000) \
	{ \
		(_a_)->tv_sec  += (_a_)->tv_usec / 1000000; \
		(_a_)->tv_usec  = (_a_)->tv_usec % 1000000; \
	} \
	if ((_a_)->tv_usec < 0) \
	{ \
		(_a_)->tv_sec  -= 1 + (-(_a_)->tv_usec / 1000000); \
		(_a_)->tv_usec = 999999 - (-(_a_)->tv_usec - 1); \
	}

#ifdef timeradd
#undef timeradd
#endif
#define timeradd(_a_, _b_) \
	(_a_)->tv_sec  += (_b_)->tv_sec; \
	(_a_)->tv_usec += (_b_)->tv_usec; \
	timernormalize((_a_))

#ifdef timersub
#undef timersub
#endif
#define timersub(_a_, _b_) \
	(_a_)->tv_sec  -= (_b_)->tv_sec; \
	(_a_)->tv_usec -= (_b_)->tv_usec; \
	timernormalize((_a_))

/*
 * debug macros
 */
#define PRINTF if (interactive) printf
#define LPRINTF if (interactive && loop_filter_debug) printf

#ifdef DEBUG
#define DPRINTF(_x_) LPRINTF _x_
#else
#define DPRINTF(_x_)
#endif

#ifdef DECL_ERRNO
     extern int errno;
#endif

static char *revision = "4.18";

/*
 * display received data (avoids also detaching from tty)
 */
static int interactive = 0;

/*
 * display loopfilter (clock control) variables
 */
static int loop_filter_debug = 0;

/*
 * do not set/adjust system time
 */
static int no_set = 0;

/*
 * time that passes between start of DCF impulse and time stamping (fine
 * adjustment) in microseconds (receiver/OS dependent)
 */
#define DEFAULT_DELAY	230000	/* rough estimate */

/*
 * The two states we can be in - eithe we receive nothing
 * usable or we have the correct time
 */
#define NO_SYNC		0x01
#define SYNC		0x02

static int    sync_state = NO_SYNC;
static time_t last_sync;

static unsigned long ticks = 0;

static char pat[] = "-\\|/";

#define LINES		(24-2)	/* error lines after which the two headlines are repeated */

#define MAX_UNSYNC	(10*60)	/* allow synchronisation loss for 10 minutes */
#define NOTICE_INTERVAL (20*60)	/* mention missing synchronisation every 20 minutes */

/*
 * clock adjustment PLL - see NTP protocol spec (RFC1305) for details
 */

#define USECSCALE	10
#define TIMECONSTANT	2
#define ADJINTERVAL	0
#define FREQ_WEIGHT	18
#define PHASE_WEIGHT	7
#define MAX_DRIFT	0x3FFFFFFF

#define R_SHIFT(_X_, _Y_) (((_X_) < 0) ? -(-(_X_) >> (_Y_)) : ((_X_) >> (_Y_)))

static long max_adj_offset_usec = 128000;

static long clock_adjust = 0;	/* current adjustment value (usec * 2^USECSCALE) */
static long accum_drift   = 0;	/* accumulated drift value  (usec / ADJINTERVAL) */
static long adjustments  = 0;
static char skip_adjust  = 1;	/* discard first adjustment (bad samples) */

/*
 * DCF77 state flags
 */
#define DCFB_ANNOUNCE		0x0001 /* switch time zone warning (DST switch) */
#define DCFB_DST		0x0002 /* DST in effect */
#define DCFB_LEAP		0x0004 /* LEAP warning (1 hour prior to occurrence) */
#define DCFB_CALLBIT		0x0008 /* "call bit" used to signalize irregularities in the control facilities */

struct clocktime		/* clock time broken up from time code */
{
	long wday;		/* Day of week: 1: Monday - 7: Sunday */
	long day;
	long month;
	long year;
	long hour;
	long minute;
	long second;
	long usecond;
	long utcoffset;	/* in minutes */
	long flags;		/* current clock status  (DCF77 state flags) */
};

typedef struct clocktime clocktime_t;

/*
 * (usually) quick constant multiplications
 */
#ifndef TIMES10
#define TIMES10(_X_) (((_X_) << 3) + ((_X_) << 1))	/* *8 + *2 */
#endif
#ifndef TIMES24
#define TIMES24(_X_) (((_X_) << 4) + ((_X_) << 3))      /* *16 + *8 */
#endif
#ifndef TIMES60
#define TIMES60(_X_) ((((_X_) << 4)  - (_X_)) << 2)     /* *(16 - 1) *4 */
#endif

/*
 * generic l_abs() function
 */
#define l_abs(_x_)     (((_x_) < 0) ? -(_x_) : (_x_))

/*
 * conversion related return/error codes
 */
#define CVT_MASK	0x0000000F /* conversion exit code */
#define   CVT_NONE	0x00000001 /* format not applicable */
#define   CVT_FAIL	0x00000002 /* conversion failed - error code returned */
#define   CVT_OK	0x00000004 /* conversion succeeded */
#define CVT_BADFMT	0x00000010 /* general format error - (unparsable) */
#define CVT_BADDATE	0x00000020 /* invalid date */
#define CVT_BADTIME	0x00000040 /* invalid time */

/*
 * DCF77 raw time code
 *
 * From "Zur Zeit", Physikalisch-Technische Bundesanstalt (PTB), Braunschweig
 * und Berlin, Maerz 1989
 *
 * Timecode transmission:
 * AM:
 *	time marks are send every second except for the second before the
 *	next minute mark
 *	time marks consist of a reduction of transmitter power to 25%
 *	of the nominal level
 *	the falling edge is the time indication (on time)
 *	time marks of a 100ms duration constitute a logical 0
 *	time marks of a 200ms duration constitute a logical 1
 * FM:
 *	see the spec. (basically a (non-)inverted psuedo random phase shift)
 *
 * Encoding:
 * Second	Contents
 * 0  - 10	AM: free, FM: 0
 * 11 - 14	free
 * 15		R     - "call bit" used to signalize irregularities in the control facilities
 *		        (until 2003 indicated transmission via alternate antenna)
 * 16		A1    - expect zone change (1 hour before)
 * 17 - 18	Z1,Z2 - time zone
 *		 0  0 illegal
 *		 0  1 MEZ  (MET)
 *		 1  0 MESZ (MED, MET DST)
 *		 1  1 illegal
 * 19		A2    - expect leap insertion/deletion (1 hour before)
 * 20		S     - start of time code (1)
 * 21 - 24	M1    - BCD (lsb first) Minutes
 * 25 - 27	M10   - BCD (lsb first) 10 Minutes
 * 28		P1    - Minute Parity (even)
 * 29 - 32	H1    - BCD (lsb first) Hours
 * 33 - 34      H10   - BCD (lsb first) 10 Hours
 * 35		P2    - Hour Parity (even)
 * 36 - 39	D1    - BCD (lsb first) Days
 * 40 - 41	D10   - BCD (lsb first) 10 Days
 * 42 - 44	DW    - BCD (lsb first) day of week (1: Monday -> 7: Sunday)
 * 45 - 49	MO    - BCD (lsb first) Month
 * 50           MO0   - 10 Months
 * 51 - 53	Y1    - BCD (lsb first) Years
 * 54 - 57	Y10   - BCD (lsb first) 10 Years
 * 58 		P3    - Date Parity (even)
 * 59		      - usually missing (minute indication), except for leap insertion
 */

/*-----------------------------------------------------------------------
 * conversion table to map DCF77 bit stream into data fields.
 * Encoding:
 *   Each field of the DCF77 code is described with two adjacent entries in
 *   this table. The first entry specifies the offset into the DCF77 data stream
 *   while the length is given as the difference between the start index and
 *   the start index of the following field.
 */
static struct rawdcfcode
{
	char offset;			/* start bit */
} rawdcfcode[] =
{
	{  0 }, { 15 }, { 16 }, { 17 }, { 19 }, { 20 }, { 21 }, { 25 }, { 28 }, { 29 },
	{ 33 }, { 35 }, { 36 }, { 40 }, { 42 }, { 45 }, { 49 }, { 50 }, { 54 }, { 58 }, { 59 }
};

/*-----------------------------------------------------------------------
 * symbolic names for the fields of DCF77 describes in "rawdcfcode".
 * see comment above for the structure of the DCF77 data
 */
#define DCF_M	0
#define DCF_R	1
#define DCF_A1	2
#define DCF_Z	3
#define DCF_A2	4
#define DCF_S	5
#define DCF_M1	6
#define DCF_M10	7
#define DCF_P1	8
#define DCF_H1	9
#define DCF_H10	10
#define DCF_P2	11
#define DCF_D1	12
#define DCF_D10	13
#define DCF_DW	14
#define DCF_MO	15
#define DCF_MO0	16
#define DCF_Y1	17
#define DCF_Y10	18
#define DCF_P3	19

/*-----------------------------------------------------------------------
 * parity field table (same encoding as rawdcfcode)
 * This table describes the sections of the DCF77 code that are
 * parity protected
 */
static struct partab
{
	char offset;			/* start bit of parity field */
} partab[] =
{
	{ 21 }, { 29 }, { 36 }, { 59 }
};

/*-----------------------------------------------------------------------
 * offsets for parity field descriptions
 */
#define DCF_P_P1	0
#define DCF_P_P2	1
#define DCF_P_P3	2

/*-----------------------------------------------------------------------
 * legal values for time zone information
 */
#define DCF_Z_MET 0x2
#define DCF_Z_MED 0x1

/*-----------------------------------------------------------------------
 * symbolic representation if the DCF77 data stream
 */
static struct dcfparam
{
	unsigned char onebits[60];
	unsigned char zerobits[60];
} dcfparam =
{
	"###############RADMLS1248124P124812P1248121241248112481248P", /* 'ONE' representation */
	"--------------------s-------p------p----------------------p"  /* 'ZERO' representation */
};

/*-----------------------------------------------------------------------
 * extract a bitfield from DCF77 datastream
 * All numeric fields are LSB first.
 * buf holds a pointer to a DCF77 data buffer in symbolic
 *     representation
 * idx holds the index to the field description in rawdcfcode
 */
static unsigned long
ext_bf(
	register unsigned char *buf,
	register int   idx
	)
{
	register unsigned long sum = 0;
	register int i, first;

	first = rawdcfcode[idx].offset;

	for (i = rawdcfcode[idx+1].offset - 1; i >= first; i--)
	{
		sum <<= 1;
		sum |= (buf[i] != dcfparam.zerobits[i]);
	}
	return sum;
}

/*-----------------------------------------------------------------------
 * check even parity integrity for a bitfield
 *
 * buf holds a pointer to a DCF77 data buffer in symbolic
 *     representation
 * idx holds the index to the field description in partab
 */
static unsigned
pcheck(
	register unsigned char *buf,
	register int   idx
	)
{
	register int i,last;
	register unsigned psum = 1;

	last = partab[idx+1].offset;

	for (i = partab[idx].offset; i < last; i++)
	    psum ^= (buf[i] != dcfparam.zerobits[i]);

	return psum;
}

/*-----------------------------------------------------------------------
 * convert a DCF77 data buffer into wall clock time + flags
 *
 * buffer holds a pointer to a DCF77 data buffer in symbolic
 *        representation
 * size   describes the length of DCF77 information in bits (represented
 *        as chars in symbolic notation
 * clock  points to a wall clock time description of the DCF77 data (result)
 */
static unsigned long
convert_rawdcf(
	       unsigned char   *buffer,
	       int              size,
	       clocktime_t     *clock_time
	       )
{
	if (size < 57)
	{
		PRINTF("%-30s", "*** INCOMPLETE");
		return CVT_NONE;
	}

	/*
	 * check Start and Parity bits
	 */
	if ((ext_bf(buffer, DCF_S) == 1) &&
	    pcheck(buffer, DCF_P_P1) &&
	    pcheck(buffer, DCF_P_P2) &&
	    pcheck(buffer, DCF_P_P3))
	{
		/*
		 * buffer OK - extract all fields and build wall clock time from them
		 */

		clock_time->flags  = 0;
		clock_time->usecond= 0;
		clock_time->second = 0;
		clock_time->minute = ext_bf(buffer, DCF_M10);
		clock_time->minute = TIMES10(clock_time->minute) + ext_bf(buffer, DCF_M1);
		clock_time->hour   = ext_bf(buffer, DCF_H10);
		clock_time->hour   = TIMES10(clock_time->hour)   + ext_bf(buffer, DCF_H1);
		clock_time->day    = ext_bf(buffer, DCF_D10);
		clock_time->day    = TIMES10(clock_time->day)    + ext_bf(buffer, DCF_D1);
		clock_time->month  = ext_bf(buffer, DCF_MO0);
		clock_time->month  = TIMES10(clock_time->month)  + ext_bf(buffer, DCF_MO);
		clock_time->year   = ext_bf(buffer, DCF_Y10);
		clock_time->year   = TIMES10(clock_time->year)   + ext_bf(buffer, DCF_Y1);
		clock_time->wday   = ext_bf(buffer, DCF_DW);

		/*
		 * determine offset to UTC by examining the time zone
		 */
		switch (ext_bf(buffer, DCF_Z))
		{
		    case DCF_Z_MET:
			clock_time->utcoffset = -60;
			break;

		    case DCF_Z_MED:
			clock_time->flags     |= DCFB_DST;
			clock_time->utcoffset  = -120;
			break;

		    default:
			PRINTF("%-30s", "*** BAD TIME ZONE");
			return CVT_FAIL|CVT_BADFMT;
		}

		/*
		 * extract various warnings from DCF77
		 */
		if (ext_bf(buffer, DCF_A1))
		    clock_time->flags |= DCFB_ANNOUNCE;

		if (ext_bf(buffer, DCF_A2))
		    clock_time->flags |= DCFB_LEAP;

		if (ext_bf(buffer, DCF_R))
		    clock_time->flags |= DCFB_CALLBIT;

		return CVT_OK;
	}
	else
	{
		/*
		 * bad format - not for us
		 */
		PRINTF("%-30s", "*** BAD FORMAT (invalid/parity)");
		return CVT_FAIL|CVT_BADFMT;
	}
}

/*-----------------------------------------------------------------------
 * raw dcf input routine - fix up 50 baud
 * characters for 1/0 decision
 */
static unsigned long
cvt_rawdcf(
	   unsigned char   *buffer,
	   int              size,
	   clocktime_t     *clock_time
	   )
{
	register unsigned char *s = buffer;
	register unsigned char *e = buffer + size;
	register unsigned char *b = dcfparam.onebits;
	register unsigned char *c = dcfparam.zerobits;
	register unsigned rtc = CVT_NONE;
	register unsigned int i, lowmax, highmax, cutoff, span;
#define BITS 9
	unsigned char     histbuf[BITS];
	/*
	 * the input buffer contains characters with runs of consecutive
	 * bits set. These set bits are an indication of the DCF77 pulse
	 * length. We assume that we receive the pulse at 50 Baud. Thus
	 * a 100ms pulse would generate a 4 bit train (20ms per bit and
	 * start bit)
	 * a 200ms pulse would create all zeroes (and probably a frame error)
	 *
	 * The basic idea is that on corret reception we must have two
	 * maxima in the pulse length distribution histogram. (one for
	 * the zero representing pulses and one for the one representing
	 * pulses)
	 * There will always be ones in the datastream, thus we have to see
	 * two maxima.
	 * The best point to cut for a 1/0 decision is the minimum between those
	 * between the maxima. The following code tries to find this cutoff point.
	 */

	/*
	 * clear histogram buffer
	 */
	for (i = 0; i < BITS; i++)
	{
		histbuf[i] = 0;
	}

	cutoff = 0;
	lowmax = 0;

	/*
	 * convert sequences of set bits into bits counts updating
	 * the histogram alongway
	 */
	while (s < e)
	{
		register unsigned int ch = *s ^ 0xFF;
		/*
		 * check integrity and update histogramm
		 */
		if (!((ch+1) & ch) || !*s)
		{
			/*
			 * character ok
			 */
			for (i = 0; ch; i++)
			{
				ch >>= 1;
			}

			*s = i;
			histbuf[i]++;
			cutoff += i;
			lowmax++;
		}
		else
		{
			/*
			 * invalid character (no consecutive bit sequence)
			 */
			DPRINTF(("parse: cvt_rawdcf: character check for 0x%x@%ld FAILED\n",
				 (u_int)*s, (long)(s - buffer)));
			*s = (unsigned char)~0;
			rtc = CVT_FAIL|CVT_BADFMT;
		}
		s++;
	}

	/*
	 * first cutoff estimate (average bit count - must be between both
	 * maxima)
	 */
	if (lowmax)
	{
		cutoff /= lowmax;
	}
	else
	{
		cutoff = 4;	/* doesn't really matter - it'll fail anyway, but gives error output */
	}

	DPRINTF(("parse: cvt_rawdcf: average bit count: %d\n", cutoff));

	lowmax = 0;  /* weighted sum */
	highmax = 0; /* bitcount */

	/*
	 * collect weighted sum of lower bits (left of initial guess)
	 */
	DPRINTF(("parse: cvt_rawdcf: histogram:"));
	for (i = 0; i <= cutoff; i++)
	{
		lowmax  += histbuf[i] * i;
		highmax += histbuf[i];
		DPRINTF((" %d", histbuf[i]));
	}
	DPRINTF((" <M>"));

	/*
	 * round up
	 */
	lowmax += highmax / 2;

	/*
	 * calculate lower bit maximum (weighted sum / bit count)
	 *
	 * avoid divide by zero
	 */
	if (highmax)
	{
		lowmax /= highmax;
	}
	else
	{
		lowmax = 0;
	}

	highmax = 0; /* weighted sum of upper bits counts */
	cutoff = 0;  /* bitcount */

	/*
	 * collect weighted sum of lower bits (right of initial guess)
	 */
	for (; i < BITS; i++)
	{
		highmax+=histbuf[i] * i;
		cutoff +=histbuf[i];
		DPRINTF((" %d", histbuf[i]));
	}
	DPRINTF(("\n"));

	/*
	 * determine upper maximum (weighted sum / bit count)
	 */
	if (cutoff)
	{
		highmax /= cutoff;
	}
	else
	{
		highmax = BITS-1;
	}

	/*
	 * following now holds:
	 * lowmax <= cutoff(initial guess) <= highmax
	 * best cutoff is the minimum nearest to higher bits
	 */

	/*
	 * find the minimum between lowmax and highmax (detecting
	 * possibly a minimum span)
	 */
	span = cutoff = lowmax;
	for (i = lowmax; i <= highmax; i++)
	{
		if (histbuf[cutoff] > histbuf[i])
		{
			/*
			 * got a new minimum move beginning of minimum (cutoff) and
			 * end of minimum (span) there
			 */
			cutoff = span = i;
		}
		else
		    if (histbuf[cutoff] == histbuf[i])
		    {
			    /*
			     * minimum not better yet - but it spans more than
			     * one bit value - follow it
			     */
			    span = i;
		    }
	}

	/*
	 * cutoff point for 1/0 decision is the middle of the minimum section
	 * in the histogram
	 */
	cutoff = (cutoff + span) / 2;

	DPRINTF(("parse: cvt_rawdcf: lower maximum %d, higher maximum %d, cutoff %d\n", lowmax, highmax, cutoff));

	/*
	 * convert the bit counts to symbolic 1/0 information for data conversion
	 */
	s = buffer;
	while ((s < e) && *c && *b)
	{
		if (*s == (unsigned char)~0)
		{
			/*
			 * invalid character
			 */
			*s = '?';
		}
		else
		{
			/*
			 * symbolic 1/0 representation
			 */
			*s = (*s >= cutoff) ? *b : *c;
		}
		s++;
		b++;
		c++;
	}

	/*
	 * if everything went well so far return the result of the symbolic
	 * conversion routine else just the accumulated errors
	 */
	if (rtc != CVT_NONE)
	{
		PRINTF("%-30s", "*** BAD DATA");
	}

	return (rtc == CVT_NONE) ? convert_rawdcf(buffer, size, clock_time) : rtc;
}

/*-----------------------------------------------------------------------
 * convert a wall clock time description of DCF77 to a Unix time (seconds
 * since 1.1. 1970 UTC)
 */
static time_t
dcf_to_unixtime(
		clocktime_t   *clock_time,
		unsigned *cvtrtc
		)
{
#define SETRTC(_X_)	{ if (cvtrtc) *cvtrtc = (_X_); }
	static int days_of_month[] =
	{
		0, 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31
	};
	register int i;
	time_t t;

	/*
	 * map 2 digit years to 19xx (DCF77 is a 20th century item)
	 */
	if ( clock_time->year < YEAR_PIVOT ) 	/* in case of	   Y2KFixes [ */
		clock_time->year += 100;	/* *year%100, make tm_year */
						/* *(do we need this?) */
	if ( clock_time->year < YEAR_BREAK )	/* (failsafe if) */
	    clock_time->year += 1900;				/* Y2KFixes ] */

	/*
	 * must have been a really bad year code - drop it
	 */
	if (clock_time->year < (YEAR_PIVOT + 1900) )		/* Y2KFixes */
	{
		SETRTC(CVT_FAIL|CVT_BADDATE);
		return -1;
	}
	/*
	 * sorry, slow section here - but it's not time critical anyway
	 */

	/*
	 * calculate days since 1970 (watching leap years)
	 */
	t = julian0( clock_time->year ) - julian0( 1970 );

  				/* month */
	if (clock_time->month <= 0 || clock_time->month > 12)
	{
		SETRTC(CVT_FAIL|CVT_BADDATE);
		return -1;		/* bad month */
	}
				/* adjust current leap year */
#if 0
	if (clock_time->month < 3 && days_per_year(clock_time->year) == 366)
	    t--;
#endif

	/*
	 * collect days from months excluding the current one
	 */
	for (i = 1; i < clock_time->month; i++)
	{
		t += days_of_month[i];
	}
				/* day */
	if (clock_time->day < 1 || ((clock_time->month == 2 && days_per_year(clock_time->year) == 366) ?
			       clock_time->day > 29 : clock_time->day > days_of_month[clock_time->month]))
	{
		SETRTC(CVT_FAIL|CVT_BADDATE);
		return -1;		/* bad day */
	}

	/*
	 * collect days from date excluding the current one
	 */
	t += clock_time->day - 1;

				/* hour */
	if (clock_time->hour < 0 || clock_time->hour >= 24)
	{
		SETRTC(CVT_FAIL|CVT_BADTIME);
		return -1;		/* bad hour */
	}

	/*
	 * calculate hours from 1. 1. 1970
	 */
	t = TIMES24(t) + clock_time->hour;

  				/* min */
	if (clock_time->minute < 0 || clock_time->minute > 59)
	{
		SETRTC(CVT_FAIL|CVT_BADTIME);
		return -1;		/* bad min */
	}

	/*
	 * calculate minutes from 1. 1. 1970
	 */
	t = TIMES60(t) + clock_time->minute;
				/* sec */

	/*
	 * calculate UTC in minutes
	 */
	t += clock_time->utcoffset;

	if (clock_time->second < 0 || clock_time->second > 60)	/* allow for LEAPs */
	{
		SETRTC(CVT_FAIL|CVT_BADTIME);
		return -1;		/* bad sec */
	}

	/*
	 * calculate UTC in seconds - phew !
	 */
	t  = TIMES60(t) + clock_time->second;
				/* done */
	return t;
}

/*-----------------------------------------------------------------------
 * cheap half baked 1/0 decision - for interactive operation only
 */
static char
type(
     unsigned int c
     )
{
	c ^= 0xFF;
	return (c > 0xF);
}

/*-----------------------------------------------------------------------
 * week day representation
 */
static const char *wday[8] =
{
	"??",
	"Mo",
	"Tu",
	"We",
	"Th",
	"Fr",
	"Sa",
	"Su"
};

/*-----------------------------------------------------------------------
 * generate a string representation for a timeval
 */
static char *
pr_timeval(
	struct timeval *val
	)
{
	static char buf[20];

	if (val->tv_sec == 0)
		snprintf(buf, sizeof(buf), "%c0.%06ld",
			 (val->tv_usec < 0) ? '-' : '+',
			 (long int)l_abs(val->tv_usec));
	else
		snprintf(buf, sizeof(buf), "%ld.%06ld",
			 (long int)val->tv_sec,
			 (long int)l_abs(val->tv_usec));
	return buf;
}

/*-----------------------------------------------------------------------
 * correct the current time by an offset by setting the time rigorously
 */
static void
set_time(
	 struct timeval *offset
	 )
{
	struct timeval the_time;

	if (no_set)
	    return;

	LPRINTF("set_time: %s ", pr_timeval(offset));
	syslog(LOG_NOTICE, "setting time (offset %s)", pr_timeval(offset));

	if (gettimeofday(&the_time, 0L) == -1)
	{
		perror("gettimeofday()");
	}
	else
	{
		timeradd(&the_time, offset);
		if (settimeofday(&the_time, 0L) == -1)
		{
			perror("settimeofday()");
		}
	}
}

/*-----------------------------------------------------------------------
 * slew the time by a given offset
 */
static void
adj_time(
	 long offset
	 )
{
	struct timeval time_offset;

	if (no_set)
	    return;

	time_offset.tv_sec  = offset / 1000000;
	time_offset.tv_usec = offset % 1000000;

	LPRINTF("adj_time: %ld us ", (long int)offset);
	if (adjtime(&time_offset, 0L) == -1)
	    perror("adjtime()");
}

/*-----------------------------------------------------------------------
 * read in a possibly previously written drift value
 */
static void
read_drift(
	   const char *drift_file
	   )
{
	FILE *df;

	df = fopen(drift_file, "r");
	if (df != NULL)
	{
		int idrift = 0, fdrift = 0;

		if (2 != fscanf(df, "%4d.%03d", &idrift, &fdrift))
			LPRINTF("read_drift: trouble reading drift file");
		fclose(df);
		LPRINTF("read_drift: %d.%03d ppm ", idrift, fdrift);

		accum_drift = idrift << USECSCALE;
		fdrift     = (fdrift << USECSCALE) / 1000;
		accum_drift += fdrift & (1<<USECSCALE);
		LPRINTF("read_drift: drift_comp %ld ", (long int)accum_drift);
	}
}

/*-----------------------------------------------------------------------
 * write out the current drift value
 */
static void
update_drift(
	     const char *drift_file,
	     long offset,
	     time_t reftime
	     )
{
	FILE *df;

	df = fopen(drift_file, "w");
	if (df != NULL)
	{
		int idrift = R_SHIFT(accum_drift, USECSCALE);
		int fdrift = accum_drift & ((1<<USECSCALE)-1);

		LPRINTF("update_drift: drift_comp %ld ", (long int)accum_drift);
		fdrift = (fdrift * 1000) / (1<<USECSCALE);
		fprintf(df, "%4d.%03d %c%ld.%06ld %.24s\n", idrift, fdrift,
			(offset < 0) ? '-' : '+', (long int)(l_abs(offset) / 1000000),
			(long int)(l_abs(offset) % 1000000), asctime(localtime(&reftime)));
		fclose(df);
		LPRINTF("update_drift: %d.%03d ppm ", idrift, fdrift);
	}
}

/*-----------------------------------------------------------------------
 * process adjustments derived from the DCF77 observation
 * (controls clock PLL)
 */
static void
adjust_clock(
	     struct timeval *offset,
	     const char *drift_file,
	     time_t reftime
	     )
{
	struct timeval toffset;
	register long usecoffset;
	int tmp;

	if (no_set)
	    return;

	if (skip_adjust)
	{
		skip_adjust = 0;
		return;
	}

	toffset = *offset;
	toffset.tv_sec  = l_abs(toffset.tv_sec);
	toffset.tv_usec = l_abs(toffset.tv_usec);
	if (toffset.tv_sec ||
	    (!toffset.tv_sec && toffset.tv_usec > max_adj_offset_usec))
	{
		/*
		 * hopeless - set the clock - and clear the timing
		 */
		set_time(offset);
		clock_adjust = 0;
		skip_adjust  = 1;
		return;
	}

	usecoffset   = offset->tv_sec * 1000000 + offset->tv_usec;

	clock_adjust = R_SHIFT(usecoffset, TIMECONSTANT);	/* adjustment to make for next period */

	tmp = 0;
	while (adjustments > (1 << tmp))
	    tmp++;
	adjustments = 0;
	if (tmp > FREQ_WEIGHT)
	    tmp = FREQ_WEIGHT;

	accum_drift  += R_SHIFT(usecoffset << USECSCALE, TIMECONSTANT+TIMECONSTANT+FREQ_WEIGHT-tmp);

	if (accum_drift > MAX_DRIFT)		/* clamp into interval */
	    accum_drift = MAX_DRIFT;
	else
	    if (accum_drift < -MAX_DRIFT)
		accum_drift = -MAX_DRIFT;

	update_drift(drift_file, usecoffset, reftime);
	LPRINTF("clock_adjust: %s, clock_adjust %ld, drift_comp %ld(%ld) ",
		pr_timeval(offset),(long int) R_SHIFT(clock_adjust, USECSCALE),
		(long int)R_SHIFT(accum_drift, USECSCALE), (long int)accum_drift);
}

/*-----------------------------------------------------------------------
 * adjust the clock by a small mount to simulate frequency correction
 */
static void
periodic_adjust(
		void
		)
{
	register long adjustment;

	adjustments++;

	adjustment = R_SHIFT(clock_adjust, PHASE_WEIGHT);

	clock_adjust -= adjustment;

	adjustment += R_SHIFT(accum_drift, USECSCALE+ADJINTERVAL);

	adj_time(adjustment);
}

/*-----------------------------------------------------------------------
 * control synchronisation status (warnings) and do periodic adjusts
 * (frequency control simulation)
 */
static void
tick(
     int signum
     )
{
	static unsigned long last_notice = 0;

#if !defined(HAVE_SIGACTION) && !defined(HAVE_SIGVEC)
	(void)signal(SIGALRM, tick);
#endif

	periodic_adjust();

	ticks += 1<<ADJINTERVAL;

	if ((ticks - last_sync) > MAX_UNSYNC)
	{
		/*
		 * not getting time for a while
		 */
		if (sync_state == SYNC)
		{
			/*
			 * completely lost information
			 */
			sync_state = NO_SYNC;
			syslog(LOG_INFO, "DCF77 reception lost (timeout)");
			last_notice = ticks;
		}
		else
		    /*
		     * in NO_SYNC state - look whether its time to speak up again
		     */
		    if ((ticks - last_notice) > NOTICE_INTERVAL)
		    {
			    syslog(LOG_NOTICE, "still not synchronized to DCF77 - check receiver/signal");
			    last_notice = ticks;
		    }
	}

#ifndef ITIMER_REAL
	(void) alarm(1<<ADJINTERVAL);
#endif
}

/*-----------------------------------------------------------------------
 * break association from terminal to avoid catching terminal
 * or process group related signals (-> daemon operation)
 */
static void
detach(
       void
       )
{
#   ifdef HAVE_DAEMON
	if (daemon(0, 0)) {
		fprintf(stderr, "'daemon()' fails: %d(%s)\n",
			errno, strerror(errno));
	}
#   else /* not HAVE_DAEMON */
	if (fork())
	    exit(0);

	{
		u_long s;
		int max_fd;

#if defined(HAVE_SYSCONF) && defined(_SC_OPEN_MAX)
		max_fd = sysconf(_SC_OPEN_MAX);
#else /* HAVE_SYSCONF && _SC_OPEN_MAX */
		max_fd = getdtablesize();
#endif /* HAVE_SYSCONF && _SC_OPEN_MAX */
		for (s = 0; s < max_fd; s++)
		    (void) close((int)s);
		(void) open("/", 0);
		(void) dup2(0, 1);
		(void) dup2(0, 2);
#ifdef SYS_DOMAINOS
		{
			uid_$t puid;
			status_$t st;

			proc2_$who_am_i(&puid);
			proc2_$make_server(&puid, &st);
		}
#endif /* SYS_DOMAINOS */
#if defined(HAVE_SETPGID) || defined(HAVE_SETSID)
# ifdef HAVE_SETSID
		if (setsid() == (pid_t)-1)
		    syslog(LOG_ERR, "dcfd: setsid(): %m");
# else
		if (setpgid(0, 0) == -1)
		    syslog(LOG_ERR, "dcfd: setpgid(): %m");
# endif
#else /* HAVE_SETPGID || HAVE_SETSID */
		{
			int fid;

			fid = open("/dev/tty", 2);
			if (fid >= 0)
			{
				(void) ioctl(fid, (u_long) TIOCNOTTY, (char *) 0);
				(void) close(fid);
			}
# ifdef HAVE_SETPGRP_0
			(void) setpgrp();
# else /* HAVE_SETPGRP_0 */
			(void) setpgrp(0, getpid());
# endif /* HAVE_SETPGRP_0 */
		}
#endif /* HAVE_SETPGID || HAVE_SETSID */
	}
#endif /* not HAVE_DAEMON */
}

/*-----------------------------------------------------------------------
 * list possible arguments and options
 */
static void
usage(
      char *program
      )
{
  fprintf(stderr, "usage: %s [-n] [-f] [-l] [-t] [-i] [-o] [-d <drift_file>] [-D <input delay>] <device>\n", program);
	fprintf(stderr, "\t-n              do not change time\n");
	fprintf(stderr, "\t-i              interactive\n");
	fprintf(stderr, "\t-t              trace (print all datagrams)\n");
	fprintf(stderr, "\t-f              print all databits (includes PTB private data)\n");
	fprintf(stderr, "\t-l              print loop filter debug information\n");
	fprintf(stderr, "\t-o              print offet average for current minute\n");
	fprintf(stderr, "\t-Y              make internal Y2K checks then exit\n");	/* Y2KFixes */
	fprintf(stderr, "\t-d <drift_file> specify alternate drift file\n");
	fprintf(stderr, "\t-D <input delay>specify delay from input edge to processing in micro seconds\n");
}

/*-----------------------------------------------------------------------
 * check_y2k() - internal check of Y2K logic
 *	(a lot of this logic lifted from ../ntpd/check_y2k.c)
 */
static int
check_y2k( void )
{
    int  year;			/* current working year */
    int  year0 = 1900;		/* sarting year for NTP time */
    int  yearend;		/* ending year we test for NTP time.
				    * 32-bit systems: through 2036, the
				      **year in which NTP time overflows.
				    * 64-bit systems: a reasonable upper
				      **limit (well, maybe somewhat beyond
				      **reasonable, but well before the
				      **max time, by which time the earth
				      **will be dead.) */
    time_t Time;
    struct tm LocalTime;

    int Fatals, Warnings;
#define Error(year) if ( (year)>=2036 && LocalTime.tm_year < 110 ) \
	Warnings++; else Fatals++

    Fatals = Warnings = 0;

    Time = time( (time_t *)NULL );
    LocalTime = *localtime( &Time );

    year = ( sizeof( u_long ) > 4 ) 	/* save max span using year as temp */
		? ( 400 * 3 ) 		/* three greater gregorian cycles */
		: ((int)(0x7FFFFFFF / 365.242 / 24/60/60)* 2 ); /*32-bit limit*/
			/* NOTE: will automacially expand test years on
			 * 64 bit machines.... this may cause some of the
			 * existing ntp logic to fail for years beyond
			 * 2036 (the current 32-bit limit). If all checks
			 * fail ONLY beyond year 2036 you may ignore such
			 * errors, at least for a decade or so. */
    yearend = year0 + year;

    year = 1900+YEAR_PIVOT;
    printf( "  starting year %04d\n", (int) year );
    printf( "  ending year   %04d\n", (int) yearend );

    for ( ; year < yearend; year++ )
    {
	clocktime_t  ct;
	time_t	     Observed;
	time_t	     Expected;
	unsigned     Flag;
	unsigned long t;

	ct.day = 1;
	ct.month = 1;
	ct.year = year;
	ct.hour = ct.minute = ct.second = ct.usecond = 0;
	ct.utcoffset = 0;
	ct.flags = 0;

	Flag = 0;
 	Observed = dcf_to_unixtime( &ct, &Flag );
		/* seems to be a clone of parse_to_unixtime() with
		 * *a minor difference to arg2 type */
	if ( ct.year != year )
	{
	    fprintf( stdout,
	       "%04d: dcf_to_unixtime(,%d) CORRUPTED ct.year: was %d\n",
	       (int)year, (int)Flag, (int)ct.year );
	    Error(year);
	    break;
	}
	t = julian0(year) - julian0(1970);	/* Julian day from 1970 */
	Expected = t * 24 * 60 * 60;
	if ( Observed != Expected  ||  Flag )
	{   /* time difference */
	    fprintf( stdout,
	       "%04d: dcf_to_unixtime(,%d) FAILURE: was=%lu s/b=%lu  (%ld)\n",
	       year, (int)Flag,
	       (unsigned long)Observed, (unsigned long)Expected,
	       ((long)Observed - (long)Expected) );
	    Error(year);
	    break;
	}

    }

    return ( Fatals );
}

/*--------------------------------------------------
 * rawdcf_init - set up modem lines for RAWDCF receivers
 */
#if defined(TIOCMSET) && (defined(TIOCM_DTR) || defined(CIOCM_DTR))
static void
rawdcf_init(
	int fd
	)
{
	/*
	 * You can use the RS232 to supply the power for a DCF77 receiver.
	 * Here a voltage between the DTR and the RTS line is used. Unfortunately
	 * the name has changed from CIOCM_DTR to TIOCM_DTR recently.
	 */

#ifdef TIOCM_DTR
	int sl232 = TIOCM_DTR;	/* turn on DTR for power supply */
#else
	int sl232 = CIOCM_DTR;	/* turn on DTR for power supply */
#endif

	if (ioctl(fd, TIOCMSET, (caddr_t)&sl232) == -1)
	{
		syslog(LOG_NOTICE, "rawdcf_init: WARNING: ioctl(fd, TIOCMSET, [C|T]IOCM_DTR): %m");
	}
}
#else
static void
rawdcf_init(
	    int fd
	)
{
	syslog(LOG_NOTICE, "rawdcf_init: WARNING: OS interface incapable of setting DTR to power DCF modules");
}
#endif  /* DTR initialisation type */

/*-----------------------------------------------------------------------
 * main loop - argument interpreter / setup / main loop
 */
int
main(
     int argc,
     char **argv
     )
{
	unsigned char c;
	char **a = argv;
	int  ac = argc;
	char *file = NULL;
	const char *drift_file = "/etc/dcfd.drift";
	int fd;
	int offset = 15;
	int offsets = 0;
	int delay = DEFAULT_DELAY;	/* average delay from input edge to time stamping */
	int trace = 0;
	int errs = 0;

	/*
	 * process arguments
	 */
	while (--ac)
	{
		char *arg = *++a;
		if (*arg == '-')
		    while ((c = *++arg))
			switch (c)
			{
			    case 't':
				trace = 1;
				interactive = 1;
				break;

			    case 'f':
				offset = 0;
				interactive = 1;
				break;

			    case 'l':
				loop_filter_debug = 1;
				offsets = 1;
				interactive = 1;
				break;

			    case 'n':
				no_set = 1;
				break;

			    case 'o':
				offsets = 1;
				interactive = 1;
				break;

			    case 'i':
				interactive = 1;
				break;

			    case 'D':
				if (ac > 1)
				{
					delay = atoi(*++a);
					ac--;
				}
				else
				{
					fprintf(stderr, "%s: -D requires integer argument\n", argv[0]);
					errs=1;
				}
				break;

			    case 'd':
				if (ac > 1)
				{
					drift_file = *++a;
					ac--;
				}
				else
				{
					fprintf(stderr, "%s: -d requires file name argument\n", argv[0]);
					errs=1;
				}
				break;

			    case 'Y':
				errs=check_y2k();
				exit( errs ? 1 : 0 );

			    default:
				fprintf(stderr, "%s: unknown option -%c\n", argv[0], c);
				errs=1;
				break;
			}
		else
		    if (file == NULL)
			file = arg;
		    else
		    {
			    fprintf(stderr, "%s: device specified twice\n", argv[0]);
			    errs=1;
		    }
	}

	if (errs)
	{
		usage(argv[0]);
		exit(1);
	}
	else
	    if (file == NULL)
	    {
		    fprintf(stderr, "%s: device not specified\n", argv[0]);
		    usage(argv[0]);
		    exit(1);
	    }

	errs = LINES+1;

	/*
	 * get access to DCF77 tty port
	 */
	fd = open(file, O_RDONLY);
	if (fd == -1)
	{
		perror(file);
		exit(1);
	}
	else
	{
		int i, rrc;
		struct timeval t, tt, tlast;
		struct timeval timeout;
		struct timeval phase;
		struct timeval time_offset;
		char pbuf[61];		/* printable version */
		char buf[61];		/* raw data */
		clocktime_t clock_time;	/* wall clock time */
		time_t utc_time = 0;
		time_t last_utc_time = 0;
		long usecerror = 0;
		long lasterror = 0;
#if defined(HAVE_TERMIOS_H) || defined(STREAM)
		struct termios term;
#else  /* not HAVE_TERMIOS_H || STREAM */
# if defined(HAVE_TERMIO_H) || defined(HAVE_SYSV_TTYS)
		struct termio term;
# endif/* HAVE_TERMIO_H || HAVE_SYSV_TTYS */
#endif /* not HAVE_TERMIOS_H || STREAM */
		unsigned int rtc = CVT_NONE;

		rawdcf_init(fd);

		timeout.tv_sec  = 1;
		timeout.tv_usec = 500000;

		phase.tv_sec    = 0;
		phase.tv_usec   = delay;

		/*
		 * setup TTY (50 Baud, Read, 8Bit, No Hangup, 1 character IO)
		 */
		if (TTY_GETATTR(fd,  &term) == -1)
		{
			perror("tcgetattr");
			exit(1);
		}

		memset(term.c_cc, 0, sizeof(term.c_cc));
		term.c_cc[VMIN] = 1;
#ifdef NO_PARENB_IGNPAR
		term.c_cflag = CS8|CREAD|CLOCAL;
#else
		term.c_cflag = CS8|CREAD|CLOCAL|PARENB;
#endif
		term.c_iflag = IGNPAR;
		term.c_oflag = 0;
		term.c_lflag = 0;

		cfsetispeed(&term, B50);
		cfsetospeed(&term, B50);

		if (TTY_SETATTR(fd, &term) == -1)
		{
			perror("tcsetattr");
			exit(1);
		}

		/*
		 * lose terminal if in daemon operation
		 */
		if (!interactive)
		    detach();

		/*
		 * get syslog() initialized
		 */
#ifdef LOG_DAEMON
		openlog("dcfd", LOG_PID, LOG_DAEMON);
#else
		openlog("dcfd", LOG_PID);
#endif

		/*
		 * setup periodic operations (state control / frequency control)
		 */
#ifdef HAVE_SIGACTION
		{
			struct sigaction act;

# ifdef HAVE_SA_SIGACTION_IN_STRUCT_SIGACTION
			act.sa_sigaction = (void (*) (int, siginfo_t *, void *))0;
# endif /* HAVE_SA_SIGACTION_IN_STRUCT_SIGACTION */
			act.sa_handler   = tick;
			sigemptyset(&act.sa_mask);
			act.sa_flags     = 0;

			if (sigaction(SIGALRM, &act, (struct sigaction *)0) == -1)
			{
				syslog(LOG_ERR, "sigaction(SIGALRM): %m");
				exit(1);
			}
		}
#else
#ifdef HAVE_SIGVEC
		{
			struct sigvec vec;

			vec.sv_handler   = tick;
			vec.sv_mask      = 0;
			vec.sv_flags     = 0;

			if (sigvec(SIGALRM, &vec, (struct sigvec *)0) == -1)
			{
				syslog(LOG_ERR, "sigvec(SIGALRM): %m");
				exit(1);
			}
		}
#else
		(void) signal(SIGALRM, tick);
#endif
#endif

#ifdef ITIMER_REAL
		{
			struct itimerval it;

			it.it_interval.tv_sec  = 1<<ADJINTERVAL;
			it.it_interval.tv_usec = 0;
			it.it_value.tv_sec     = 1<<ADJINTERVAL;
			it.it_value.tv_usec    = 0;

			if (setitimer(ITIMER_REAL, &it, (struct itimerval *)0) == -1)
			{
				syslog(LOG_ERR, "setitimer: %m");
				exit(1);
			}
		}
#else
		(void) alarm(1<<ADJINTERVAL);
#endif

		PRINTF("  DCF77 monitor %s - Copyright (C) 1993-2005 by Frank Kardel\n\n", revision);

		pbuf[60] = '\0';
		for ( i = 0; i < 60; i++)
		    pbuf[i] = '.';

		read_drift(drift_file);

		/*
		 * what time is it now (for interval measurement)
		 */
		gettimeofday(&tlast, 0L);
		i = 0;
		/*
		 * loop until input trouble ...
		 */
		do
		{
			/*
			 * get an impulse
			 */
			while ((rrc = read(fd, &c, 1)) == 1)
			{
				gettimeofday(&t, 0L);
				tt = t;
				timersub(&t, &tlast);

				if (errs > LINES)
				{
					PRINTF("  %s", &"PTB private....RADMLSMin....PHour..PMDay..DayMonthYear....P\n"[offset]);
					PRINTF("  %s", &"---------------RADMLS1248124P124812P1248121241248112481248P\n"[offset]);
					errs = 0;
				}

				/*
				 * timeout -> possible minute mark -> interpretation
				 */
				if (timercmp(&t, &timeout, >))
				{
					PRINTF("%c %.*s ", pat[i % (sizeof(pat)-1)], 59 - offset, &pbuf[offset]);

					if ((rtc = cvt_rawdcf((unsigned char *)buf, i, &clock_time)) != CVT_OK)
					{
						/*
						 * this data was bad - well - forget synchronisation for now
						 */
						PRINTF("\n");
						if (sync_state == SYNC)
						{
							sync_state = NO_SYNC;
							syslog(LOG_INFO, "DCF77 reception lost (bad data)");
						}
						errs++;
					}
					else
					    if (trace)
					    {
						    PRINTF("\r  %.*s ", 59 - offset, &buf[offset]);
					    }


					buf[0] = c;

					/*
					 * collect first character
					 */
					if (((c^0xFF)+1) & (c^0xFF))
					    pbuf[0] = '?';
					else
					    pbuf[0] = type(c) ? '#' : '-';

					for ( i = 1; i < 60; i++)
					    pbuf[i] = '.';

					i = 0;
				}
				else
				{
					/*
					 * collect character
					 */
					buf[i] = c;

					/*
					 * initial guess (usually correct)
					 */
					if (((c^0xFF)+1) & (c^0xFF))
					    pbuf[i] = '?';
					else
					    pbuf[i] = type(c) ? '#' : '-';

					PRINTF("%c %.*s ", pat[i % (sizeof(pat)-1)], 59 - offset, &pbuf[offset]);
				}

				if (i == 0 && rtc == CVT_OK)
				{
					/*
					 * we got a good time code here - try to convert it to
					 * UTC
					 */
					if ((utc_time = dcf_to_unixtime(&clock_time, &rtc)) == -1)
					{
						PRINTF("*** BAD CONVERSION\n");
					}

					if (utc_time != (last_utc_time + 60))
					{
						/*
						 * well, two successive sucessful telegrams are not 60 seconds
						 * apart
						 */
						PRINTF("*** NO MINUTE INC\n");
						if (sync_state == SYNC)
						{
							sync_state = NO_SYNC;
							syslog(LOG_INFO, "DCF77 reception lost (data mismatch)");
						}
						errs++;
						rtc = CVT_FAIL|CVT_BADTIME|CVT_BADDATE;
					}
					else
					    usecerror = 0;

					last_utc_time = utc_time;
				}

				if (rtc == CVT_OK)
				{
					if (i == 0)
					{
						/*
						 * valid time code - determine offset and
						 * note regained reception
						 */
						last_sync = ticks;
						if (sync_state == NO_SYNC)
						{
							syslog(LOG_INFO, "receiving DCF77");
						}
						else
						{
							/*
							 * we had at least one minute SYNC - thus
							 * last error is valid
							 */
							time_offset.tv_sec  = lasterror / 1000000;
							time_offset.tv_usec = lasterror % 1000000;
							adjust_clock(&time_offset, drift_file, utc_time);
						}
						sync_state = SYNC;
					}

					time_offset.tv_sec  = utc_time + i;
					time_offset.tv_usec = 0;

					timeradd(&time_offset, &phase);

					usecerror += (time_offset.tv_sec - tt.tv_sec) * 1000000 + time_offset.tv_usec
						-tt.tv_usec;

					/*
					 * output interpreted DCF77 data
					 */
					PRINTF(offsets ? "%s, %2ld:%02ld:%02d, %ld.%02ld.%02ld, <%s%s%s%s> (%c%ld.%06lds)" :
					       "%s, %2ld:%02ld:%02d, %ld.%02ld.%02ld, <%s%s%s%s>",
					       wday[clock_time.wday],
					       clock_time.hour, clock_time.minute, i, clock_time.day, clock_time.month,
					       clock_time.year,
					       (clock_time.flags & DCFB_CALLBIT) ? "R" : "_",
					       (clock_time.flags & DCFB_ANNOUNCE) ? "A" : "_",
					       (clock_time.flags & DCFB_DST) ? "D" : "_",
					       (clock_time.flags & DCFB_LEAP) ? "L" : "_",
					       (lasterror < 0) ? '-' : '+', l_abs(lasterror) / 1000000, l_abs(lasterror) % 1000000
					       );

					if (trace && (i == 0))
					{
						PRINTF("\n");
						errs++;
					}
					lasterror = usecerror / (i+1);
				}
				else
				{
					lasterror = 0; /* we cannot calculate phase errors on bad reception */
				}

				PRINTF("\r");

				if (i < 60)
				{
					i++;
				}

				tlast = tt;

				if (interactive)
				    fflush(stdout);
			}
		} while ((rrc == -1) && (errno == EINTR));

		/*
		 * lost IO - sorry guys
		 */
		syslog(LOG_ERR, "TERMINATING - cannot read from device %s (%m)", file);

		(void)close(fd);
	}

	closelog();

	return 0;
}

/*
 * History:
 *
 * dcfd.c,v
 * Revision 4.18  2005/10/07 22:08:18  kardel
 * make dcfd.c compile on NetBSD 3.99.9 again (configure/sigvec compatibility fix)
 *
 * Revision 4.17.2.1  2005/10/03 19:15:16  kardel
 * work around configure not detecting a missing sigvec compatibility
 * interface on NetBSD 3.99.9 and above
 *
 * Revision 4.17  2005/08/10 10:09:44  kardel
 * output revision information
 *
 * Revision 4.16  2005/08/10 06:33:25  kardel
 * cleanup warnings
 *
 * Revision 4.15  2005/08/10 06:28:45  kardel
 * fix setting of baud rate
 *
 * Revision 4.14  2005/04/16 17:32:10  kardel
 * update copyright
 *
 * Revision 4.13  2004/11/14 15:29:41  kardel
 * support PPSAPI, upgrade Copyright to Berkeley style
 *
 */