clk_rawdcf.c

网络时间协议NTP 源码 版本v4.2.0b 该源码用于linux平台下

/*
 * /src/NTP/ntp4-dev/libparse/clk_rawdcf.c,v 4.15 2005/08/06 19:17:06 kardel RELEASE_20050806_B
 *  
 * clk_rawdcf.c,v 4.15 2005/08/06 19:17:06 kardel RELEASE_20050806_B
 *
 * Raw DCF77 pulse clock support
 *
 * Copyright (c) 1995-2005 by Frank Kardel <kardel <AT> ntp.org>
 * Copyright (c) 1989-1994 by Frank Kardel, Friedrich-Alexander Universit鋞 Erlangen-N黵nberg, 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

#if defined(REFCLOCK) && defined(CLOCK_PARSE) && defined(CLOCK_RAWDCF)

#include "ntp_fp.h"
#include "ntp_unixtime.h"
#include "ntp_calendar.h"

#include "parse.h"
#ifdef PARSESTREAM
# include <sys/parsestreams.h>
#endif

#ifndef PARSEKERNEL
# include "ntp_stdlib.h"
#endif

/*
 * 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     - 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
 */

static u_long pps_rawdcf P((parse_t *, int, timestamp_t *));
static u_long cvt_rawdcf P((unsigned char *, int, struct format *, clocktime_t *, void *));
static u_long inp_rawdcf P((parse_t *, unsigned int, timestamp_t  *));

typedef struct last_tcode {
	time_t tcode;	/* last converted time code */
} last_tcode_t;

#define BUFFER_MAX	61

clockformat_t clock_rawdcf =
{
  inp_rawdcf,			/* DCF77 input handling */
  cvt_rawdcf,			/* raw dcf input conversion */
  pps_rawdcf,			/* examining PPS information */
  0,				/* no private configuration data */
  "RAW DCF77 Timecode",		/* direct decoding / time synthesis */

  BUFFER_MAX,			/* bit buffer */
  sizeof(last_tcode_t)
};

static struct dcfparam
{
	unsigned char *onebits;
	unsigned char *zerobits;
} dcfparameter = 
{
	"###############RADMLS1248124P124812P1248121241248112481248P", /* 'ONE' representation */
	"--------------------s-------p------p----------------------p"  /* 'ZERO' representation */
};

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 }
};

#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

static struct partab
{
	char offset;			/* start bit of parity field */
} partab[] =
{
	{ 21 }, { 29 }, { 36 }, { 59 }
};

#define DCF_P_P1	0
#define DCF_P_P2	1
#define DCF_P_P3	2

#define DCF_Z_MET 0x2
#define DCF_Z_MED 0x1

static u_long
ext_bf(
	unsigned char *buf,
	int   idx,
	unsigned char *zero
	)
{
	u_long sum = 0;
	int i, first;

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

static unsigned
pcheck(
       unsigned char *buf,
       int   idx,
       unsigned char *zero
       )
{
	int i,last;
	unsigned psum = 1;

	last = partab[idx+1].offset;

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

	return psum;
}

static u_long
convert_rawdcf(
	       unsigned char   *buffer,
	       int              size,
	       struct dcfparam *dcfprm,
	       clocktime_t     *clock_time
	       )
{
	unsigned char *s = buffer;
	unsigned char *b = dcfprm->onebits;
	unsigned char *c = dcfprm->zerobits;
	int i;

	parseprintf(DD_RAWDCF,("parse: convert_rawdcf: \"%s\"\n", buffer));

	if (size < 57)
	{
#ifndef PARSEKERNEL
		msyslog(LOG_ERR, "parse: convert_rawdcf: INCOMPLETE DATA - time code only has %d bits\n", size);
#endif
		return CVT_NONE;
	}
  
	for (i = 0; i < size; i++)
	{
		if ((*s != *b) && (*s != *c))
		{
			/*
			 * we only have two types of bytes (ones and zeros)
			 */
#ifndef PARSEKERNEL
			msyslog(LOG_ERR, "parse: convert_rawdcf: BAD DATA - no conversion");
#endif
			return CVT_NONE;
		}
		if (*b) b++;
		if (*c) c++;
		s++;
	}

	/*
	 * check Start and Parity bits
	 */
	if ((ext_bf(buffer, DCF_S, dcfprm->zerobits) == 1) &&
	    pcheck(buffer, DCF_P_P1, dcfprm->zerobits) &&
	    pcheck(buffer, DCF_P_P2, dcfprm->zerobits) &&
	    pcheck(buffer, DCF_P_P3, dcfprm->zerobits))
	{
		/*
		 * buffer OK
		 */
		parseprintf(DD_RAWDCF,("parse: convert_rawdcf: parity check passed\n"));

		clock_time->flags  = PARSEB_S_ANTENNA|PARSEB_S_LEAP;
		clock_time->utctime= 0;
		clock_time->usecond= 0;
		clock_time->second = 0;
		clock_time->minute = ext_bf(buffer, DCF_M10, dcfprm->zerobits);
		clock_time->minute = TIMES10(clock_time->minute) + ext_bf(buffer, DCF_M1, dcfprm->zerobits);
		clock_time->hour   = ext_bf(buffer, DCF_H10, dcfprm->zerobits);
		clock_time->hour   = TIMES10(clock_time->hour) + ext_bf(buffer, DCF_H1, dcfprm->zerobits);
		clock_time->day    = ext_bf(buffer, DCF_D10, dcfprm->zerobits);
		clock_time->day    = TIMES10(clock_time->day) + ext_bf(buffer, DCF_D1, dcfprm->zerobits);
		clock_time->month  = ext_bf(buffer, DCF_MO0, dcfprm->zerobits);
		clock_time->month  = TIMES10(clock_time->month) + ext_bf(buffer, DCF_MO, dcfprm->zerobits);
		clock_time->year   = ext_bf(buffer, DCF_Y10, dcfprm->zerobits);
		clock_time->year   = TIMES10(clock_time->year) + ext_bf(buffer, DCF_Y1, dcfprm->zerobits);

		switch (ext_bf(buffer, DCF_Z, dcfprm->zerobits))
		{
		    case DCF_Z_MET:
			clock_time->utcoffset = -1*60*60;
			break;

		    case DCF_Z_MED:
			clock_time->flags     |= PARSEB_DST;
			clock_time->utcoffset  = -2*60*60;
			break;

		    default:
			parseprintf(DD_RAWDCF,("parse: convert_rawdcf: BAD TIME ZONE\n"));
			return CVT_FAIL|CVT_BADFMT;
		}

		if (ext_bf(buffer, DCF_A1, dcfprm->zerobits))
		    clock_time->flags |= PARSEB_ANNOUNCE;

		if (ext_bf(buffer, DCF_A2, dcfprm->zerobits))
		    clock_time->flags |= PARSEB_LEAPADD; /* default: DCF77 data format deficiency */

		if (ext_bf(buffer, DCF_R, dcfprm->zerobits))
		    clock_time->flags |= PARSEB_ALTERNATE;

		parseprintf(DD_RAWDCF,("parse: convert_rawdcf: TIME CODE OK: %d:%d, %d.%d.%d, flags 0x%lx\n",
				       (int)clock_time->hour, (int)clock_time->minute, (int)clock_time->day, (int)clock_time->month,(int) clock_time->year,
				       (u_long)clock_time->flags));
		return CVT_OK;
	}
	else
	{
		/*
		 * bad format - not for us
		 */
#ifndef PARSEKERNEL
		msyslog(LOG_ERR, "parse: convert_rawdcf: parity check FAILED for \"%s\"\n", buffer);
#endif
		return CVT_FAIL|CVT_BADFMT;