/* $NetBSD: refclock_hpgps.c,v 1.6 2024/08/18 20:47:18 christos Exp $ */

/* $NetBSD: refclock_hpgps.c,v 1.6 2024/08/18 20:47:18 christos Exp $ */

/*
* refclock_hpgps - clock driver for HP 58503A GPS receiver
*/

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

#if defined(REFCLOCK) && defined(CLOCK_HPGPS)

#include "ntpd.h"
#include "ntp_io.h"
#include "ntp_refclock.h"
#include "ntp_stdlib.h"

#include <stdio.h>
#include <ctype.h>

/* Version 0.1 April 1, 1995
* 0.2 April 25, 1995
* tolerant of missing timecode response prompt and sends
* clear status if prompt indicates error;
* can use either local time or UTC from receiver;
* can get receiver status screen via flag4
*
* WARNING!: This driver is UNDER CONSTRUCTION
* Everything in here should be treated with suspicion.
* If it looks wrong, it probably is.
*
* Comments and/or questions to: Dave Vitanye
* Hewlett Packard Company
* [email protected]
* (408) 553-2856
*
* Thanks to the author of the PST driver, which was the starting point for
* this one.
*
* This driver supports the HP 58503A Time and Frequency Reference Receiver.
* This receiver uses HP SmartClock (TM) to implement an Enhanced GPS receiver.
* The receiver accuracy when locked to GPS in normal operation is better
* than 1 usec. The accuracy when operating in holdover is typically better
* than 10 usec. per day.
*
* The same driver also handles the HP Z3801A which is available surplus
* from the cell phone industry. It's popular with hams.
* It needs a different line setup: 19200 baud, 7 data bits, odd parity
* That is selected by adding "mode 1" to the server line in ntp.conf
* HP Z3801A code from Jeff Mock added by Hal Murray, Sep 2005
*
*
* The receiver should be operated with factory default settings.
* Initial driver operation: expects the receiver to be already locked
* to GPS, configured and able to output timecode format 2 messages.
*
* The driver uses the poll sequence :PTIME:TCODE? to get a response from
* the receiver. The receiver responds with a timecode string of ASCII
* printing characters, followed by a <cr><lf>, followed by a prompt string
* issued by the receiver, in the following format:
* T#yyyymmddhhmmssMFLRVcc<cr><lf>scpi >
*
* The driver processes the response at the <cr> and <lf>, so what the
* driver sees is the prompt from the previous poll, followed by this
* timecode. The prompt from the current poll is (usually) left unread until
* the next poll. So (except on the very first poll) the driver sees this:
*
* scpi > T#yyyymmddhhmmssMFLRVcc<cr><lf>
*
* The T is the on-time character, at 980 msec. before the next 1PPS edge.
* The # is the timecode format type. We look for format 2.
* Without any of the CLK or PPS stuff, then, the receiver buffer timestamp
* at the <cr> is 24 characters later, which is about 25 msec. at 9600 bps,
* so the first approximation for fudge time1 is nominally -0.955 seconds.
* This number probably needs adjusting for each machine / OS type, so far:
* -0.955000 on an HP 9000 Model 712/80 HP-UX 9.05
* -0.953175 on an HP 9000 Model 370 HP-UX 9.10
*
* This receiver also provides a 1PPS signal, but I haven't figured out
* how to deal with any of the CLK or PPS stuff yet. Stay tuned.
*
*/

/*
* Fudge Factors
*
* Fudge time1 is used to accomodate the timecode serial interface adjustment.
* Fudge flag4 can be set to request a receiver status screen summary, which
* is recorded in the clockstats file.
*/

/*
* Interface definitions
*/
#define DEVICE "/dev/hpgps%d" /* device name and unit */
#define SPEED232 B9600 /* uart speed (9600 baud) */
#define SPEED232Z B19200 /* uart speed (19200 baud) */
#define PRECISION (-10) /* precision assumed (about 1 ms) */
#define REFID "GPS\0" /* reference ID */
#define DESCRIPTION "HP 58503A GPS Time and Frequency Reference Receiver"

#define SMAX 23*80+1 /* for :SYSTEM:PRINT? status screen response */

#define MTZONE 2 /* number of fields in timezone reply */
#define MTCODET2 12 /* number of fields in timecode format T2 */
#define NTCODET2 21 /* number of chars to checksum in format T2 */

/*
* Tables to compute the day of year from yyyymmdd timecode.
* Viva la leap.
*/
static int day1tab[] = {31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31};
static int day2tab[] = {31, 29, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31};

/*
* Unit control structure
*/
struct hpgpsunit {
int pollcnt; /* poll message counter */
int tzhour; /* timezone offset, hours */
int tzminute; /* timezone offset, minutes */
int linecnt; /* set for expected multiple line responses */
char *lastptr; /* pointer to receiver response data */
char statscrn[SMAX]; /* receiver status screen buffer */
};

/*
* Function prototypes
*/
static int hpgps_start (int, struct peer *);
static void hpgps_shutdown (int, struct peer *);
static void hpgps_receive (struct recvbuf *);
static void hpgps_poll (int, struct peer *);

/*
* Transfer vector
*/
struct refclock refclock_hpgps = {
hpgps_start, /* start up driver */
hpgps_shutdown, /* shut down driver */
hpgps_poll, /* transmit poll message */
noentry, /* not used (old hpgps_control) */
noentry, /* initialize driver */
noentry, /* not used (old hpgps_buginfo) */
NOFLAGS /* not used */
};

/*
* hpgps_start - open the devices and initialize data for processing
*/
static int
hpgps_start(
int unit,
struct peer *peer
)
{
register struct hpgpsunit *up;
struct refclockproc *pp;
int fd;
int speed, ldisc;
char device[20];

/*
* Open serial port. Use CLK line discipline, if available.
* Default is HP 58503A, mode arg selects HP Z3801A
*/
snprintf(device, sizeof(device), DEVICE, unit);
ldisc = LDISC_CLK;
speed = SPEED232;
/* mode parameter to server config line shares ttl slot */
if (1 == peer->ttl) {
ldisc |= LDISC_7O1;
speed = SPEED232Z;
}
fd = refclock_open(&peer->srcadr, device, speed, ldisc);
if (fd <= 0)
return (0);
/*
* Allocate and initialize unit structure
*/
up = emalloc_zero(sizeof(*up));
pp = peer->procptr;
pp->io.clock_recv = hpgps_receive;
pp->io.srcclock = peer;
pp->io.datalen = 0;
pp->io.fd = fd;
if (!io_addclock(&pp->io)) {
close(fd);
pp->io.fd = -1;
free(up);
return (0);
}
pp->unitptr = up;

/*
* Initialize miscellaneous variables
*/
peer->precision = PRECISION;
pp->clockdesc = DESCRIPTION;
memcpy((char *)&pp->refid, REFID, 4);
up->tzhour = 0;
up->tzminute = 0;

*up->statscrn = '\0';
up->lastptr = up->statscrn;
up->pollcnt = 2;

/*
* Get the identifier string, which is logged but otherwise ignored,
* and get the local timezone information
*/
up->linecnt = 1;
if (refclock_write(peer, "*IDN?\r:PTIME:TZONE?\r", 20, NULL) != 20)
refclock_report(peer, CEVNT_FAULT);

return (1);
}

/*
* hpgps_shutdown - shut down the clock
*/
static void
hpgps_shutdown(
int unit,
struct peer *peer
)
{
register struct hpgpsunit *up;
struct refclockproc *pp;

pp = peer->procptr;
up = pp->unitptr;
if (-1 != pp->io.fd)
io_closeclock(&pp->io);
if (NULL != up)
free(up);
}

/*
* hpgps_receive - receive data from the serial interface
*/
static void
hpgps_receive(
struct recvbuf *rbufp
)
{
register struct hpgpsunit *up;
struct refclockproc *pp;
struct peer *peer;
l_fp trtmp;
char tcodechar1; /* identifies timecode format */
char tcodechar2; /* identifies timecode format */
char timequal; /* time figure of merit: 0-9 */
char freqqual; /* frequency figure of merit: 0-3 */
char leapchar; /* leapsecond: + or 0 or - */
char servchar; /* request for service: 0 = no, 1 = yes */
char syncchar; /* time info is invalid: 0 = no, 1 = yes */
short expectedsm; /* expected timecode byte checksum */
short tcodechksm; /* computed timecode byte checksum */
int i,m,n;
int month, day, lastday;
char *tcp; /* timecode pointer (skips over the prompt) */
char prompt[BMAX]; /* prompt in response from receiver */

/*
* Initialize pointers and read the receiver response
*/
peer = rbufp->recv_peer;
pp = peer->procptr;
up = pp->unitptr;
*pp->a_lastcode = '\0';
pp->lencode = refclock_gtlin(rbufp, pp->a_lastcode, BMAX, &trtmp);

#ifdef DEBUG
if (debug)
printf("hpgps: lencode: %d timecode:%s\n",
pp->lencode, pp->a_lastcode);
#endif

/*
* If there's no characters in the reply, we can quit now
*/
if (pp->lencode == 0)
return;

/*
* If linecnt is greater than zero, we are getting information only,
* such as the receiver identification string or the receiver status
* screen, so put the receiver response at the end of the status
* screen buffer. When we have the last line, write the buffer to
* the clockstats file and return without further processing.
*
* If linecnt is zero, we are expecting either the timezone
* or a timecode. At this point, also write the response
* to the clockstats file, and go on to process the prompt (if any),
* timezone, or timecode and timestamp.
*/

if (up->linecnt-- > 0) {
if ((int)(pp->lencode + 2) <= (SMAX - (up->lastptr - up->statscrn))) {
*up->lastptr++ = '\n';
memcpy(up->lastptr, pp->a_lastcode, pp->lencode);
up->lastptr += pp->lencode;
}
if (up->linecnt == 0)
record_clock_stats(&peer->srcadr, up->statscrn);

return;
}

record_clock_stats(&peer->srcadr, pp->a_lastcode);
pp->lastrec = trtmp;

up->lastptr = up->statscrn;
*up->lastptr = '\0';
up->pollcnt = 2;

/*
* We get down to business: get a prompt if one is there, issue
* a clear status command if it contains an error indication.
* Next, check for either the timezone reply or the timecode reply
* and decode it. If we don't recognize the reply, or don't get the
* proper number of decoded fields, or get an out of range timezone,
* or if the timecode checksum is bad, then we declare bad format
* and exit.
*
* Timezone format (including nominal prompt):
* scpi > -H,-M<cr><lf>
*
* Timecode format (including nominal prompt):
* scpi > T2yyyymmddhhmmssMFLRVcc<cr><lf>
*
*/

strlcpy(prompt, pp->a_lastcode, sizeof(prompt));
tcp = strrchr(pp->a_lastcode,'>');
if (tcp == NULL)
tcp = pp->a_lastcode;
else
tcp++;
prompt[tcp - pp->a_lastcode] = '\0';
while ((*tcp == ' ') || (*tcp == '\t')) tcp++;

/*
* deal with an error indication in the prompt here
*/
if (strrchr(prompt,'E') > strrchr(prompt,'s')){
#ifdef DEBUG
if (debug)
printf("hpgps: error indicated in prompt: %s\n", prompt);
#endif
if (refclock_write(peer, "*CLS\r\r", 6, NULL) != 6)
refclock_report(peer, CEVNT_FAULT);
}

/*
* make sure we got a timezone or timecode format and
* then process accordingly
*/
m = sscanf(tcp,"%c%c", &tcodechar1, &tcodechar2);

if (m != 2){
#ifdef DEBUG
if (debug)
printf("hpgps: no format indicator\n");
#endif
refclock_report(peer, CEVNT_BADREPLY);
return;
}

switch (tcodechar1) {

case '+':
case '-':
m = sscanf(tcp,"%d,%d", &up->tzhour, &up->tzminute);
if (m != MTZONE) {
#ifdef DEBUG
if (debug)
printf("hpgps: only %d fields recognized in timezone\n", m);
#endif
refclock_report(peer, CEVNT_BADREPLY);
return;
}
if ((up->tzhour < -12) || (up->tzhour > 13) ||
(up->tzminute < -59) || (up->tzminute > 59)){
#ifdef DEBUG
if (debug)
printf("hpgps: timezone %d, %d out of range\n",
up->tzhour, up->tzminute);
#endif
refclock_report(peer, CEVNT_BADREPLY);
return;
}
return;

case 'T':
break;

default:
#ifdef DEBUG
if (debug)
printf("hpgps: unrecognized reply format %c%c\n",
tcodechar1, tcodechar2);
#endif
refclock_report(peer, CEVNT_BADREPLY);
return;
} /* end of tcodechar1 switch */

switch (tcodechar2) {

case '2':
m = sscanf(tcp,"%*c%*c%4d%2d%2d%2d%2d%2d%c%c%c%c%c%2hx",
&pp->year, &month, &day, &pp->hour, &pp->minute, &pp->second,
&timequal, &freqqual, &leapchar, &servchar, &syncchar,
&expectedsm);
n = NTCODET2;

if (m != MTCODET2){
#ifdef DEBUG
if (debug)
printf("hpgps: only %d fields recognized in timecode\n", m);
#endif
refclock_report(peer, CEVNT_BADREPLY);
return;
}
break;

default:
#ifdef DEBUG
if (debug)
printf("hpgps: unrecognized timecode format %c%c\n",
tcodechar1, tcodechar2);
#endif
refclock_report(peer, CEVNT_BADREPLY);
return;
} /* end of tcodechar2 format switch */

/*
* Compute and verify the checksum.
* Characters are summed starting at tcodechar1, ending at just
* before the expected checksum. Bail out if incorrect.
*/
tcodechksm = 0;
while (n-- > 0) tcodechksm += *tcp++;
tcodechksm &= 0x00ff;

if (tcodechksm != expectedsm) {
#ifdef DEBUG
if (debug)
printf("hpgps: checksum %2hX doesn't match %2hX expected\n",
tcodechksm, expectedsm);
#endif
refclock_report(peer, CEVNT_BADREPLY);
return;
}

/*
* Compute the day of year from the yyyymmdd format.
*/
if (month < 1 || month > 12 || day < 1) {
refclock_report(peer, CEVNT_BADTIME);
return;
}

if ( ! isleap_4(pp->year) ) { /* Y2KFixes */
/* not a leap year */
if (day > day1tab[month - 1]) {
refclock_report(peer, CEVNT_BADTIME);
return;
}
for (i = 0; i < month - 1; i++) day += day1tab[i];
lastday = 365;
} else {
/* a leap year */
if (day > day2tab[month - 1]) {
refclock_report(peer, CEVNT_BADTIME);
return;
}
for (i = 0; i < month - 1; i++) day += day2tab[i];
lastday = 366;
}

/*
* Deal with the timezone offset here. The receiver timecode is in
* local time = UTC + :PTIME:TZONE, so SUBTRACT the timezone values.
* For example, Pacific Standard Time is -8 hours , 0 minutes.
* Deal with the underflows and overflows.
*/
pp->minute -= up->tzminute;
pp->hour -= up->tzhour;

if (pp->minute < 0) {
pp->minute += 60;
pp->hour--;
}
if (pp->minute > 59) {
pp->minute -= 60;
pp->hour++;
}
if (pp->hour < 0) {
pp->hour += 24;
day--;
if (day < 1) {
pp->year--;
if ( isleap_4(pp->year) ) /* Y2KFixes */
day = 366;
else
day = 365;
}
}

if (pp->hour > 23) {
pp->hour -= 24;
day++;
if (day > lastday) {
pp->year++;
day = 1;
}
}

pp->day = day;

/*
* Decode the MFLRV indicators.
* NEED TO FIGURE OUT how to deal with the request for service,
* time quality, and frequency quality indicators some day.
*/
if (syncchar != '0') {
pp->leap = LEAP_NOTINSYNC;
}
else {
pp->leap = LEAP_NOWARNING;
switch (leapchar) {

case '0':
break;

/* See http://bugs.ntp.org/1090
* Ignore leap announcements unless June or December.
* Better would be to use :GPSTime? to find the month,
* but that seems too likely to introduce other bugs.
*/
case '+':
if ((month==6) || (month==12))
pp->leap = LEAP_ADDSECOND;
break;

case '-':
if ((month==6) || (month==12))
pp->leap = LEAP_DELSECOND;
break;

default:
#ifdef DEBUG
if (debug)
printf("hpgps: unrecognized leap indicator: %c\n",
leapchar);
#endif
refclock_report(peer, CEVNT_BADTIME);
return;
} /* end of leapchar switch */
}

/*
* Process the new sample in the median filter and determine the
* reference clock offset and dispersion. We use lastrec as both
* the reference time and receive time in order to avoid being
* cute, like setting the reference time later than the receive
* time, which may cause a paranoid protocol module to chuck out
* the data.
*/
if (!refclock_process(pp)) {
refclock_report(peer, CEVNT_BADTIME);
return;
}
pp->lastref = pp->lastrec;
refclock_receive(peer);

/*
* If CLK_FLAG4 is set, ask for the status screen response.
*/
if (pp->sloppyclockflag & CLK_FLAG4){
up->linecnt = 22;
if (refclock_write(peer, ":SYSTEM:PRINT?\r", 15, NULL) != 15)
refclock_report(peer, CEVNT_FAULT);
}
}

/*
* hpgps_poll - called by the transmit procedure
*/
static void
hpgps_poll(
int unit,
struct peer *peer
)
{
register struct hpgpsunit *up;
struct refclockproc *pp;

/*
* Time to poll the clock. The HP 58503A responds to a
* ":PTIME:TCODE?" by returning a timecode in the format specified
* above. If nothing is heard from the clock for two polls,
* declare a timeout and keep going.
*/
pp = peer->procptr;
up = pp->unitptr;
if (up->pollcnt == 0)
refclock_report(peer, CEVNT_TIMEOUT);
else
up->pollcnt--;
if (refclock_write(peer, ":PTIME:TCODE?\r", 14, NULL) != 14) {
refclock_report(peer, CEVNT_FAULT);
}
else
pp->polls++;
}

#else
NONEMPTY_TRANSLATION_UNIT
#endif /* REFCLOCK */