text: /*
   * Trimble TSIP support
   * Thanks to Sven Dietrich for providing test hardware
   *
   * Copyright Frank Kardel <kardel <AT> ntp.org>
   * Copyright the NTPsec project contributors
   * SPDX-License-Identifier: BSD-3-Clause
   */
  
  #include "config.h"
  #include "ntp_syslog.h"
  #include "ntp_types.h"
  #include "ntp_fp.h"
  #include "timespecops.h"
  #include "ntp_calendar.h"
  #include "ntp_machine.h"
  #include "ntp_stdlib.h"
  
  #include "parse.h"
  
  #include <stdio.h>
  
  #include "ascii.h"
  #include "binio.h"
  #include "ieee754io.h"
  #include "trimble.h"
  #include "gpstolfp.h"
  
  /*
   * Trimble low level TSIP parser / time converter
   *
   * The receiver uses a serial message protocol called Trimble Standard
   * Interface Protocol (it can support others but this driver only supports
   * TSIP). Messages in this protocol have the following form:
   *
   * <DLE><id> ... <data> ... <DLE><ETX>
   *
   * Any bytes within the <data> portion of value 10 hex (<DLE>) are doubled
   * on transmission and compressed back to one on reception. Otherwise
   * the values of data bytes can be anything. The serial interface is RS-422
   * asynchronous using 9600 baud, 8 data bits with odd party (**note** 9 bits
   * in total!), and 1 stop bit. The protocol supports byte, integer, single,
   * and double datatypes. Integers are two bytes, sent most significant first.
   * Singles are IEEE754 single precision floating point numbers (4 byte) sent
   * sign & exponent first. Doubles are IEEE754 double precision floating point
   * numbers (8 byte) sent sign & exponent first.
   * The receiver supports a large set of messages, only a very small subset of
   * which is used here.
   *
   * From this module the following are recognised:
   *
   *  ID    Description
   *
   *  41    GPS Time
   *  46    Receiver health
   *  4F    UTC correction data (used to get leap second warnings)
   *
   * All others are accepted but ignored for time conversion - they are passed up to higher layers.
   *
   */
  
  static offsets_t trim_offsets = { 0, 1, 2, 3, 4, 5, 6, 7 };
  
  struct trimble
  {
  	uint8_t  t_in_pkt;	/* first DLE received */
  	uint8_t  t_dle;		/* subsequent DLE received */
  	unsigned short t_week;		/* GPS week */
  	unsigned short t_weekleap;	/* GPS week of next/last week */
  	unsigned short t_dayleap;	/* day in week */
  	unsigned short t_gpsutc;	/* GPS - UTC offset */
  	unsigned short t_gpsutcleap;	/* offset at next/last leap */
  	uint8_t  t_operable;	/* receiver feels OK */
  	uint8_t  t_mode;		/* actual operating mode */
  	uint8_t  t_leap;		/* possible leap warning */
          uint8_t  t_utcknown;	/* utc offset known */
  };
  
  #define STATUS_BAD    0		/* BAD or UNINITIALIZED receiver status */
  #define STATUS_UNSAFE 1		/* not enough receivers for full precision */
  #define STATUS_SYNC   2		/* enough information for good operation */
  
  static unsigned long inp_tsip (parse_t *, char, timestamp_t *);
  static unsigned long cvt_trimtsip (unsigned char *, int, struct format *, clocktime_t *, void *);
  
  struct clockformat clock_trimtsip =
  {
  	inp_tsip,		/* Trimble TSIP input handler */
  	cvt_trimtsip,		/* Trimble TSIP conversion */
  	pps_one,		/* easy PPS monitoring */
  	0,			/* no configuration data */
  	"Trimble TSIP",
  	400,			/* input buffer */
  	sizeof(struct trimble)	/* private data */
  };
  
  #define ADDSECOND	0x01
  #define DELSECOND	0x02
  
  static unsigned long
  inp_tsip(
  	 parse_t      *parseio,
  	 char         ch,
  	 timestamp_t  *tstamp
  	)
  {
  	struct trimble *t = (struct trimble *)parseio->parse_pdata;
  
  	if (!t)
  		return PARSE_INP_SKIP;		/* local data not allocated - sigh! */
  
  	if (!t->t_in_pkt && ch != DLE) {
  		/* wait for start of packet */
  		return PARSE_INP_SKIP;
  	}
  
  	if ((parseio->parse_index >= (parseio->parse_dsize - 2)) ||
  	    (parseio->parse_dtime.parse_msglen >= (sizeof(parseio->parse_dtime.parse_msg) - 2)))
  	{		/* OVERFLOW - DROP! */
  		t->t_in_pkt = t->t_dle = 0;
  		parseio->parse_index = 0;
  		parseio->parse_dtime.parse_msglen = 0;
  		return PARSE_INP_SKIP;
  	}
  
  	switch (ch) {
  	    case DLE:
  		if (!t->t_in_pkt) {
  			t->t_dle = 0;
  			t->t_in_pkt = 1;
  			parseio->parse_index = 0;
  			parseio->parse_data[parseio->parse_index++] = ch;
  			parseio->parse_dtime.parse_msglen = 0;
  			parseio->parse_dtime.parse_msg[parseio->parse_dtime.parse_msglen++] = (unsigned char)ch;
  			parseio->parse_dtime.parse_stime = *tstamp; /* pick up time stamp at packet start */
  		} else if (t->t_dle) {
  			/* Double DLE -> insert a DLE */
  			t->t_dle = 0;
  			parseio->parse_data[parseio->parse_index++] = DLE;
  			parseio->parse_dtime.parse_msg[parseio->parse_dtime.parse_msglen++] = DLE;
  		} else {
  			t->t_dle = 1;
  		}
  		break;
  
  	    case ETX:
  		if (t->t_dle) {
  			/* DLE,ETX -> end of packet */
  			parseio->parse_data[parseio->parse_index++] = DLE;
  			parseio->parse_data[parseio->parse_index] = ch;
  			parseio->parse_ldsize = (unsigned short) (parseio->parse_index + 1);
  			memcpy(parseio->parse_ldata, parseio->parse_data, parseio->parse_ldsize);
  			parseio->parse_dtime.parse_msg[parseio->parse_dtime.parse_msglen++] = DLE;
  			parseio->parse_dtime.parse_msg[parseio->parse_dtime.parse_msglen++] = (unsigned char)ch;
  			t->t_in_pkt = t->t_dle = 0;
  			return PARSE_INP_TIME|PARSE_INP_DATA;
  		}
  		/*FALLTHROUGH*/
  
  	    default:		/* collect data */
  		t->t_dle = 0;
  		parseio->parse_data[parseio->parse_index++] = ch;
  		parseio->parse_dtime.parse_msg[parseio->parse_dtime.parse_msglen++] = (unsigned char)ch;
  	}
  
  	return PARSE_INP_SKIP;
  }
  
  /*
   * cvt_trimtsip
   *
   * convert TSIP type format
   */
  static unsigned long
  cvt_trimtsip(
  	     unsigned char *buffer,
  	     int            size,
  	     struct format *format,
  	     clocktime_t   *clock_time,
  	     void          *local
  	     )
  {
          struct trimble *t = (struct trimble *)local; /* get local data space */
  #define mb(_X_) (buffer[2+(_X_)]) /* shortcut for buffer access */
  	uint8_t cmd;
  
  	UNUSED_ARG(format);
  
  	clock_time->flags = 0;
  
  	if (!t) {
  		return CVT_NONE;		/* local data not allocated - sigh! */
  	}
  
  	if ((size < 4) ||
  	    (buffer[0]      != DLE) ||
  	    (buffer[size-1] != ETX) ||
  	    (buffer[size-2] != DLE)) {
  		printf("TRIMBLE BAD packet, size %d:\n", size);
  		return CVT_NONE;
  	} else {
  		unsigned char *bp;
  		cmd = buffer[1];
  
  		switch(cmd)
  		{
  		    case CMD_RCURTIME:
  		    {			/* GPS time */
  			    l_fp secs;
  			    int week = getmsb_short(&mb(4));
  			    l_fp utcoffset;
  			    l_fp gpstime;
  
  			    bp = &mb(0);
  			    if (fetch_ieee754(&bp, IEEE_SINGLE, &secs, trim_offsets) != IEEE_OK)
  				    return CVT_FAIL|CVT_BADFMT;
  
  			    if ((lfpsint(secs) <= 0) ||
  				(t->t_utcknown == 0))
  			    {
  				    clock_time->flags = PARSEB_POWERUP;
  				    return CVT_OK;
  			    }
  			    if (week < GPSWRAP) {
  				    week += GPSWEEKS;
  			    }
  
  			    /* time OK */
  
  			    /* fetch UTC offset */
  			    bp = &mb(6);
  			    if (fetch_ieee754(&bp, IEEE_SINGLE, &utcoffset, trim_offsets) != IEEE_OK)
  				    return CVT_FAIL|CVT_BADFMT;
  
  			    secs -= utcoffset; /* adjust GPS time to UTC time */
  
  			    gpstolfp((unsigned short)week, (unsigned short)0,
  				     lfpuint(secs), &gpstime);
  
  			    setlfpfrac(gpstime, lfpfrac(secs));
  
  			    clock_time->utctime = (time_t)(lfpuint(gpstime) - JAN_1970);
  
  			    clock_time->usecond = lfp_intv_to_tspec(gpstime).tv_nsec / 1000;
  
  			    if (t->t_leap == ADDSECOND) {
  				    clock_time->flags |= PARSEB_LEAPADD;
  			    }
  			    if (t->t_leap == DELSECOND) {
  				    clock_time->flags |= PARSEB_LEAPDEL;
  			    }
  				    
  			    switch (t->t_operable) {
  				case STATUS_SYNC:
  				    clock_time->flags &= ~(PARSEB_POWERUP|PARSEB_NOSYNC);
  				    break;
  
  				case STATUS_UNSAFE:
  				    clock_time->flags |= PARSEB_NOSYNC;
  				    break;
  
  				case STATUS_BAD:
  				    clock_time->flags |= PARSEB_NOSYNC|PARSEB_POWERUP;
  				    break;
  				default:
  				    /* huh? */
  				    break;
  			    }
  
  			    if (t->t_mode == 0) {
  				    clock_time->flags |= PARSEB_POSITION;
  			    }
  			    clock_time->flags |= PARSEB_S_LEAP|PARSEB_S_POSITION;
  
  			    return CVT_OK;
  
  		    } /* case 0x41 */
  
  		    case CMD_RRECVHEALTH: 
  		    {
  			    /* TRIMBLE health */
  			    uint8_t status = mb(0);
  
  			    switch (status)
  			    {
  				case 0x00: /* position fixes */
  				    t->t_operable = STATUS_SYNC;
  				    break;
  
  				case 0x09: /* 1 satellite */
  				case 0x0A: /* 2 satellites */
  				case 0x0B: /* 3 satellites */
  				    t->t_operable = STATUS_UNSAFE;
  				    break;
  
  				default:
  				    t->t_operable = STATUS_BAD;
  				    break;
  			    }
  			    t->t_mode = status;
  		    }
  		    break;
  
  		    case CMD_RUTCPARAM:
  		    {
  			    l_fp t0t;
  			    unsigned char *lbp;
  
  			    /* UTC correction data - derive a leap warning */
  			    /* current leap correction (GPS-UTC) */
  			    int tls = t->t_gpsutc = get_msb_ushort(&mb(12));
  
  			    /* new leap correction */
  			    int tlsf = t->t_gpsutcleap = get_msb_ushort(&mb(24));
  
  			    /* week no of leap correction */
  			    t->t_weekleap = get_msb_ushort(&mb(20));
  			    if (t->t_weekleap < GPSWRAP) {
  				    t->t_weekleap = (unsigned short)(t->t_weekleap + GPSWEEKS);
  			    }
  				    
  			    /* day in week of leap correction */
  			    t->t_dayleap = get_msb_ushort(&mb(22));
  			    /* current week no */
  			    t->t_week = get_msb_ushort(&mb(18));
  			    if (t->t_week < GPSWRAP) {
  				    /* coverity[copy_paste_error] */
  				    t->t_week = (unsigned short)(t->t_weekleap + GPSWEEKS);
  			    }
  				    
  			    lbp = (unsigned char *)&mb(14); /* last update time */
  			    if (fetch_ieee754(&lbp, IEEE_SINGLE, &t0t, trim_offsets) != IEEE_OK) {
  				    return CVT_FAIL|CVT_BADFMT;
  			    }
  
  			    t->t_utcknown = lfpuint(t0t) != 0;
  
  			    if ((t->t_utcknown) && /* got UTC information */
  				(tlsf != tls)   && /* something will change */
  				((t->t_weekleap - t->t_week) < 5)) /* and close in the future */
  			    {
  				    /* generate a leap warning */
  				    if (tlsf > tls) {
  					    t->t_leap = ADDSECOND;
  				    } else {
  					    t->t_leap = DELSECOND;
  				    }
  			    } else {
  				    t->t_leap = 0;
  			    }
  		    }
  		    break;
  
  		    default:
  			/* it's validly formed, but we don't care about it! */
  			break;
  		}
  	}
  	return CVT_SKIP;
  }
  
  /*
   * History:
   *
   * clk_trimtsip.c,v
   * Revision 4.19  2009/11/01 10:47:49  kardel
   * de-P()
   *
   * Revision 4.18  2009/11/01 08:46:46  kardel
   * clarify case FALLTHROUGH
   *
   * Revision 4.17  2005/04/16 17:32:10  kardel
   * update copyright
   *
   * Revision 4.16  2004/11/14 15:29:41  kardel
   * support PPSAPI, upgrade Copyright to Berkeley style
   *
   * Revision 4.13  1999/11/28 09:13:51  kardel
   * RECON_4_0_98F
   *
   * Revision 4.12  1999/02/28 13:00:08  kardel
   * *** empty log message ***
   *
   * Revision 4.11  1999/02/28 11:47:54  kardel
   * (struct trimble): new member t_utcknown
   * (cvt_trimtsip): fixed status monitoring, bad receiver states are
   * now recognized
   *
   * Revision 4.10  1999/02/27 15:57:15  kardel
   * use mmemcpy instead of bcopy
   *
   * Revision 4.9  1999/02/21 12:17:42  kardel
   * 4.91f reconciliation
   *
   * Revision 4.8  1998/11/15 20:27:58  kardel
   * Release 4.0.73e13 reconciliation
   *
   * Revision 4.7  1998/08/16 18:49:20  kardel
   * (cvt_trimtsip): initial kernel capable version (no more floats)
   * (clock_trimtsip =): new format name
   *
   * Revision 4.6  1998/08/09 22:26:05  kardel
   * Trimble TSIP support
   *
   * Revision 4.5  1998/08/02 10:37:05  kardel
   * working TSIP parser
   *
   * Revision 4.4  1998/06/28 16:50:40  kardel
   * (getflt): fixed ENDIAN issue
   * (getdbl): fixed ENDIAN issue
   * (getint): use get_msb_short()
   * (cvt_trimtsip): use gpstolfp() for conversion
   *
   * Revision 4.3  1998/06/13 12:07:31  kardel
   * fix SYSV clock name clash
   *
   * Revision 4.2  1998/06/12 15:22:30  kardel
   * fix prototypes
   *
   * Revision 4.1  1998/05/24 09:39:54  kardel
   * implementation of the new IO handling model
   *
   * Revision 4.0  1998/04/10 19:45:32  kardel
   * Start 4.0 release version numbering
   *
   * from V3 1.8 loginfo deleted 1998/04/11 kardel
   */
  