1 /* 2 ** refclock_datum - clock driver for the Datum Programmable Time Server 3 ** 4 ** Important note: This driver assumes that you have termios. If you have 5 ** a system that does not have termios, you will have to modify this driver. 6 ** 7 ** Sorry, I have only tested this driver on SUN and HP platforms. 8 */ 9 10 #ifdef HAVE_CONFIG_H 11 # include <config.h> 12 #endif 13 14 #include "ntp_types.h" 15 16 #if defined(REFCLOCK) && defined(CLOCK_DATUM) 17 18 /* 19 ** Include Files 20 */ 21 22 #include "ntpd.h" 23 #include "ntp_io.h" 24 #include "ntp_tty.h" 25 #include "ntp_refclock.h" 26 #include "timevalops.h" 27 #include "ntp_stdlib.h" 28 29 #include <stdio.h> 30 #include <ctype.h> 31 32 #if defined(STREAM) 33 #include <stropts.h> 34 #endif /* STREAM */ 35 36 #include "ntp_stdlib.h" 37 38 /* 39 ** This driver supports the Datum Programmable Time System (PTS) clock. 40 ** The clock works in very straight forward manner. When it receives a 41 ** time code request (e.g., the ascii string "//k/mn"), it responds with 42 ** a seven byte BCD time code. This clock only responds with a 43 ** time code after it first receives the "//k/mn" message. It does not 44 ** periodically send time codes back at some rate once it is started. 45 ** the returned time code can be broken down into the following fields. 46 ** 47 ** _______________________________ 48 ** Bit Index | 7 | 6 | 5 | 4 | 3 | 2 | 1 | 0 | 49 ** =============================== 50 ** byte 0: | - - - - | H D | 51 ** =============================== 52 ** byte 1: | T D | U D | 53 ** =============================== 54 ** byte 2: | - - | T H | U H | 55 ** =============================== 56 ** byte 3: | - | T M | U M | 57 ** =============================== 58 ** byte 4: | - | T S | U S | 59 ** =============================== 60 ** byte 5: | t S | h S | 61 ** =============================== 62 ** byte 6: | m S | - - - - | 63 ** =============================== 64 ** 65 ** In the table above: 66 ** 67 ** "-" means don't care 68 ** "H D", "T D", and "U D" means Hundreds, Tens, and Units of Days 69 ** "T H", and "UH" means Tens and Units of Hours 70 ** "T M", and "U M" means Tens and Units of Minutes 71 ** "T S", and "U S" means Tens and Units of Seconds 72 ** "t S", "h S", and "m S" means tenths, hundredths, and thousandths 73 ** of seconds 74 ** 75 ** The Datum PTS communicates throught the RS232 port on your machine. 76 ** Right now, it assumes that you have termios. This driver has been tested 77 ** on SUN and HP workstations. The Datum PTS supports various IRIG and 78 ** NASA input codes. This driver assumes that the name of the device is 79 ** /dev/datum. You will need to make a soft link to your RS232 device or 80 ** create a new driver to use this refclock. 81 */ 82 83 /* 84 ** Datum PTS defines 85 */ 86 87 /* 88 ** Note that if GMT is defined, then the Datum PTS must use Greenwich 89 ** time. Otherwise, this driver allows the Datum PTS to use the current 90 ** wall clock for its time. It determines the time zone offset by minimizing 91 ** the error after trying several time zone offsets. If the Datum PTS 92 ** time is Greenwich time and GMT is not defined, everything should still 93 ** work since the time zone will be found to be 0. What this really means 94 ** is that your system time (at least to start with) must be within the 95 ** correct time by less than +- 30 minutes. The default is for GMT to not 96 ** defined. If you really want to force GMT without the funny +- 30 minute 97 ** stuff then you must define (uncomment) GMT below. 98 */ 99 100 /* 101 #define GMT 102 #define DEBUG_DATUM_PTC 103 #define LOG_TIME_ERRORS 104 */ 105 106 107 #define PRECISION (-10) /* precision assumed 1/1024 ms */ 108 #define REFID "DATM" /* reference id */ 109 #define DATUM_DISPERSION 0 /* fixed dispersion = 0 ms */ 110 #define DATUM_MAX_ERROR 0.100 /* limits on sigma squared */ 111 #define DATUM_DEV "/dev/datum" /* device name */ 112 113 #define DATUM_MAX_ERROR2 (DATUM_MAX_ERROR*DATUM_MAX_ERROR) 114 115 /* 116 ** The Datum PTS structure 117 */ 118 119 /* 120 ** I don't use a fixed array of MAXUNITS like everyone else just because 121 ** I don't like to program that way. Sorry if this bothers anyone. I assume 122 ** that you can use any id for your unit and I will search for it in a 123 ** dynamic array of units until I find it. I was worried that users might 124 ** enter a bad id in their configuration file (larger than MAXUNITS) and 125 ** besides, it is just cleaner not to have to assume that you have a fixed 126 ** number of anything in a program. 127 */ 128 129 struct datum_pts_unit { 130 struct peer *peer; /* peer used by ntp */ 131 int PTS_fd; /* file descriptor for PTS */ 132 u_int unit; /* id for unit */ 133 u_long timestarted; /* time started */ 134 l_fp lastrec; /* time tag for the receive time (system) */ 135 l_fp lastref; /* reference time (Datum time) */ 136 u_long yearstart; /* the year that this clock started */ 137 int coderecv; /* number of time codes received */ 138 int day; /* day */ 139 int hour; /* hour */ 140 int minute; /* minutes */ 141 int second; /* seconds */ 142 int msec; /* miliseconds */ 143 int usec; /* miliseconds */ 144 u_char leap; /* funny leap character code */ 145 char retbuf[8]; /* returned time from the datum pts */ 146 char nbytes; /* number of bytes received from datum pts */ 147 double sigma2; /* average squared error (roughly) */ 148 int tzoff; /* time zone offest from GMT */ 149 }; 150 151 /* 152 ** PTS static constant variables for internal use 153 */ 154 155 static char TIME_REQUEST[6]; /* request message sent to datum for time */ 156 static int nunits; /* number of active units */ 157 158 /* 159 ** Callback function prototypes that ntpd needs to know about. 160 */ 161 162 static int datum_pts_start (int, struct peer *); 163 static void datum_pts_shutdown (int, struct peer *); 164 static void datum_pts_poll (int, struct peer *); 165 static void datum_pts_control (int, const struct refclockstat *, 166 struct refclockstat *, struct peer *); 167 static void datum_pts_init (void); 168 static void datum_pts_buginfo (int, struct refclockbug *, struct peer *); 169 170 /* 171 ** This is the call back function structure that ntpd actually uses for 172 ** this refclock. 173 */ 174 175 struct refclock refclock_datum = { 176 datum_pts_start, /* start up a new Datum refclock */ 177 datum_pts_shutdown, /* shutdown a Datum refclock */ 178 datum_pts_poll, /* sends out the time request */ 179 datum_pts_control, /* not used */ 180 datum_pts_init, /* initialization (called first) */ 181 datum_pts_buginfo, /* not used */ 182 NOFLAGS /* we are not setting any special flags */ 183 }; 184 185 /* 186 ** The datum_pts_receive callback function is handled differently from the 187 ** rest. It is passed to the ntpd io data structure. Basically, every 188 ** 64 seconds, the datum_pts_poll() routine is called. It sends out the time 189 ** request message to the Datum Programmable Time System. Then, ntpd 190 ** waits on a select() call to receive data back. The datum_pts_receive() 191 ** function is called as data comes back. We expect a seven byte time 192 ** code to be returned but the datum_pts_receive() function may only get 193 ** a few bytes passed to it at a time. In other words, this routine may 194 ** get called by the io stuff in ntpd a few times before we get all seven 195 ** bytes. Once the last byte is received, we process it and then pass the 196 ** new time measurement to ntpd for updating the system time. For now, 197 ** there is no 3 state filtering done on the time measurements. The 198 ** jitter may be a little high but at least for its current use, it is not 199 ** a problem. We have tried to keep things as simple as possible. This 200 ** clock should not jitter more than 1 or 2 mseconds at the most once 201 ** things settle down. It is important to get the right drift calibrated 202 ** in the ntpd.drift file as well as getting the right tick set up right 203 ** using tickadj for SUNs. Tickadj is not used for the HP but you need to 204 ** remember to bring up the adjtime daemon because HP does not support 205 ** the adjtime() call. 206 */ 207 208 static void datum_pts_receive (struct recvbuf *); 209 210 /*......................................................................*/ 211 /* datum_pts_start - start up the datum PTS. This means open the */ 212 /* RS232 device and set up the data structure for my unit. */ 213 /*......................................................................*/ 214 215 static int 216 datum_pts_start( 217 int unit, 218 struct peer *peer 219 ) 220 { 221 struct refclockproc *pp; 222 struct datum_pts_unit *datum_pts; 223 int fd; 224 #ifdef HAVE_TERMIOS 225 int rc; 226 struct termios arg; 227 #endif 228 229 #ifdef DEBUG_DATUM_PTC 230 if (debug) 231 printf("Starting Datum PTS unit %d\n", unit); 232 #endif 233 234 /* 235 ** Open the Datum PTS device 236 */ 237 fd = open(DATUM_DEV, O_RDWR); 238 239 if (fd < 0) { 240 msyslog(LOG_ERR, "Datum_PTS: open(\"%s\", O_RDWR) failed: %m", DATUM_DEV); 241 return 0; 242 } 243 244 /* 245 ** Create the memory for the new unit 246 */ 247 datum_pts = emalloc_zero(sizeof(*datum_pts)); 248 datum_pts->unit = unit; /* set my unit id */ 249 datum_pts->yearstart = 0; /* initialize the yearstart to 0 */ 250 datum_pts->sigma2 = 0.0; /* initialize the sigma2 to 0 */ 251 252 datum_pts->PTS_fd = fd; 253 254 if (-1 == fcntl(datum_pts->PTS_fd, F_SETFL, 0)) /* clear the descriptor flags */ 255 msyslog(LOG_ERR, "MSF_ARCRON(%d): fcntl(F_SETFL, 0): %m.", 256 unit); 257 258 #ifdef DEBUG_DATUM_PTC 259 if (debug) 260 printf("Opening RS232 port with file descriptor %d\n", 261 datum_pts->PTS_fd); 262 #endif 263 264 /* 265 ** Set up the RS232 terminal device information. Note that we assume that 266 ** we have termios. This code has only been tested on SUNs and HPs. If your 267 ** machine does not have termios this driver cannot be initialized. You can change this 268 ** if you want by editing this source. Please give the changes back to the 269 ** ntp folks so that it can become part of their regular distribution. 270 */ 271 272 memset(&arg, 0, sizeof(arg)); 273 274 arg.c_iflag = IGNBRK; 275 arg.c_oflag = 0; 276 arg.c_cflag = B9600 | CS8 | CREAD | PARENB | CLOCAL; 277 arg.c_lflag = 0; 278 arg.c_cc[VMIN] = 0; /* start timeout timer right away (not used) */ 279 arg.c_cc[VTIME] = 30; /* 3 second timout on reads (not used) */ 280 281 rc = tcsetattr(datum_pts->PTS_fd, TCSANOW, &arg); 282 if (rc < 0) { 283 msyslog(LOG_ERR, "Datum_PTS: tcsetattr(\"%s\") failed: %m", DATUM_DEV); 284 close(datum_pts->PTS_fd); 285 free(datum_pts); 286 return 0; 287 } 288 289 /* 290 ** Initialize the ntpd IO structure 291 */ 292 293 datum_pts->peer = peer; 294 pp = peer->procptr; 295 pp->io.clock_recv = datum_pts_receive; 296 pp->io.srcclock = peer; 297 pp->io.datalen = 0; 298 pp->io.fd = datum_pts->PTS_fd; 299 300 if (!io_addclock(&pp->io)) { 301 pp->io.fd = -1; 302 #ifdef DEBUG_DATUM_PTC 303 if (debug) 304 printf("Problem adding clock\n"); 305 #endif 306 307 msyslog(LOG_ERR, "Datum_PTS: Problem adding clock"); 308 close(datum_pts->PTS_fd); 309 free(datum_pts); 310 311 return 0; 312 } 313 peer->procptr->unitptr = datum_pts; 314 315 /* 316 ** Now add one to the number of units and return a successful code 317 */ 318 319 nunits++; 320 return 1; 321 322 } 323 324 325 /*......................................................................*/ 326 /* datum_pts_shutdown - this routine shuts doen the device and */ 327 /* removes the memory for the unit. */ 328 /*......................................................................*/ 329 330 static void 331 datum_pts_shutdown( 332 int unit, 333 struct peer *peer 334 ) 335 { 336 struct refclockproc *pp; 337 struct datum_pts_unit *datum_pts; 338 339 #ifdef DEBUG_DATUM_PTC 340 if (debug) 341 printf("Shutdown Datum PTS\n"); 342 #endif 343 344 msyslog(LOG_ERR, "Datum_PTS: Shutdown Datum PTS"); 345 346 /* 347 ** We found the unit so close the file descriptor and free up the memory used 348 ** by the structure. 349 */ 350 pp = peer->procptr; 351 datum_pts = pp->unitptr; 352 if (NULL != datum_pts) { 353 io_closeclock(&pp->io); 354 free(datum_pts); 355 } 356 } 357 358 359 /*......................................................................*/ 360 /* datum_pts_poll - this routine sends out the time request to the */ 361 /* Datum PTS device. The time will be passed back in the */ 362 /* datum_pts_receive() routine. */ 363 /*......................................................................*/ 364 365 static void 366 datum_pts_poll( 367 int unit, 368 struct peer *peer 369 ) 370 { 371 int error_code; 372 struct datum_pts_unit *datum_pts; 373 374 datum_pts = peer->procptr->unitptr; 375 376 #ifdef DEBUG_DATUM_PTC 377 if (debug) 378 printf("Poll Datum PTS\n"); 379 #endif 380 381 /* 382 ** Find the right unit and send out a time request once it is found. 383 */ 384 error_code = write(datum_pts->PTS_fd, TIME_REQUEST, 6); 385 if (error_code != 6) 386 perror("TIME_REQUEST"); 387 datum_pts->nbytes = 0; 388 } 389 390 391 /*......................................................................*/ 392 /* datum_pts_control - not used */ 393 /*......................................................................*/ 394 395 static void 396 datum_pts_control( 397 int unit, 398 const struct refclockstat *in, 399 struct refclockstat *out, 400 struct peer *peer 401 ) 402 { 403 404 #ifdef DEBUG_DATUM_PTC 405 if (debug) 406 printf("Control Datum PTS\n"); 407 #endif 408 409 } 410 411 412 /*......................................................................*/ 413 /* datum_pts_init - initializes things for all possible Datum */ 414 /* time code generators that might be used. In practice, this is */ 415 /* only called once at the beginning before anything else is */ 416 /* called. */ 417 /*......................................................................*/ 418 419 static void 420 datum_pts_init(void) 421 { 422 423 /* */ 424 /*...... open up the log file if we are debugging ......................*/ 425 /* */ 426 427 /* 428 ** Open up the log file if we are debugging. For now, send data out to the 429 ** screen (stdout). 430 */ 431 432 #ifdef DEBUG_DATUM_PTC 433 if (debug) 434 printf("Init Datum PTS\n"); 435 #endif 436 437 /* 438 ** Initialize the time request command string. This is the only message 439 ** that we ever have to send to the Datum PTS (although others are defined). 440 */ 441 442 memcpy(TIME_REQUEST, "//k/mn",6); 443 444 /* 445 ** Initialize the number of units to 0 and set the dynamic array of units to 446 ** NULL since there are no units defined yet. 447 */ 448 449 nunits = 0; 450 451 } 452 453 454 /*......................................................................*/ 455 /* datum_pts_buginfo - not used */ 456 /*......................................................................*/ 457 458 static void 459 datum_pts_buginfo( 460 int unit, 461 register struct refclockbug *bug, 462 register struct peer *peer 463 ) 464 { 465 466 #ifdef DEBUG_DATUM_PTC 467 if (debug) 468 printf("Buginfo Datum PTS\n"); 469 #endif 470 471 } 472 473 474 /*......................................................................*/ 475 /* datum_pts_receive - receive the time buffer that was read in */ 476 /* by the ntpd io handling routines. When 7 bytes have been */ 477 /* received (it may take several tries before all 7 bytes are */ 478 /* received), then the time code must be unpacked and sent to */ 479 /* the ntpd clock_receive() routine which causes the systems */ 480 /* clock to be updated (several layers down). */ 481 /*......................................................................*/ 482 483 static void 484 datum_pts_receive( 485 struct recvbuf *rbufp 486 ) 487 { 488 int i; 489 size_t nb; 490 l_fp tstmp; 491 struct peer *p; 492 struct datum_pts_unit *datum_pts; 493 char *dpt; 494 int dpend; 495 int tzoff; 496 int timerr; 497 double ftimerr, abserr; 498 #ifdef DEBUG_DATUM_PTC 499 double dispersion; 500 #endif 501 int goodtime; 502 /*double doffset;*/ 503 504 /* 505 ** Get the time code (maybe partial) message out of the rbufp buffer. 506 */ 507 508 p = rbufp->recv_peer; 509 datum_pts = p->procptr->unitptr; 510 dpt = (char *)&rbufp->recv_space; 511 dpend = rbufp->recv_length; 512 513 #ifdef DEBUG_DATUM_PTC 514 if (debug) 515 printf("Receive Datum PTS: %d bytes\n", dpend); 516 #endif 517 518 /* */ 519 /*...... save the ntp system time when the first byte is received ......*/ 520 /* */ 521 522 /* 523 ** Save the ntp system time when the first byte is received. Note that 524 ** because it may take several calls to this routine before all seven 525 ** bytes of our return message are finally received by the io handlers in 526 ** ntpd, we really do want to use the time tag when the first byte is 527 ** received to reduce the jitter. 528 */ 529 530 nb = datum_pts->nbytes; 531 if (nb == 0) { 532 datum_pts->lastrec = rbufp->recv_time; 533 } 534 535 /* 536 ** Increment our count to the number of bytes received so far. Return if we 537 ** haven't gotten all seven bytes yet. 538 ** [Sec 3388] make sure we do not overrun the buffer. 539 ** TODO: what to do with excessive bytes, if we ever get them? 540 */ 541 for (i=0; (i < dpend) && (nb < sizeof(datum_pts->retbuf)); i++, nb++) { 542 datum_pts->retbuf[nb] = dpt[i]; 543 } 544 datum_pts->nbytes = nb; 545 546 if (nb < 7) { 547 return; 548 } 549 550 /* 551 ** Convert the seven bytes received in our time buffer to day, hour, minute, 552 ** second, and msecond values. The usec value is not used for anything 553 ** currently. It is just the fractional part of the time stored in units 554 ** of microseconds. 555 */ 556 557 datum_pts->day = 100*(datum_pts->retbuf[0] & 0x0f) + 558 10*((datum_pts->retbuf[1] & 0xf0)>>4) + 559 (datum_pts->retbuf[1] & 0x0f); 560 561 datum_pts->hour = 10*((datum_pts->retbuf[2] & 0x30)>>4) + 562 (datum_pts->retbuf[2] & 0x0f); 563 564 datum_pts->minute = 10*((datum_pts->retbuf[3] & 0x70)>>4) + 565 (datum_pts->retbuf[3] & 0x0f); 566 567 datum_pts->second = 10*((datum_pts->retbuf[4] & 0x70)>>4) + 568 (datum_pts->retbuf[4] & 0x0f); 569 570 datum_pts->msec = 100*((datum_pts->retbuf[5] & 0xf0) >> 4) + 571 10*(datum_pts->retbuf[5] & 0x0f) + 572 ((datum_pts->retbuf[6] & 0xf0)>>4); 573 574 datum_pts->usec = 1000*datum_pts->msec; 575 576 #ifdef DEBUG_DATUM_PTC 577 if (debug) 578 printf("day %d, hour %d, minute %d, second %d, msec %d\n", 579 datum_pts->day, 580 datum_pts->hour, 581 datum_pts->minute, 582 datum_pts->second, 583 datum_pts->msec); 584 #endif 585 586 /* 587 ** Get the GMT time zone offset. Note that GMT should be zero if the Datum 588 ** reference time is using GMT as its time base. Otherwise we have to 589 ** determine the offset if the Datum PTS is using time of day as its time 590 ** base. 591 */ 592 593 goodtime = 0; /* We are not sure about the time and offset yet */ 594 595 #ifdef GMT 596 597 /* 598 ** This is the case where the Datum PTS is using GMT so there is no time 599 ** zone offset. 600 */ 601 602 tzoff = 0; /* set time zone offset to 0 */ 603 604 #else 605 606 /* 607 ** This is the case where the Datum PTS is using regular time of day for its 608 ** time so we must compute the time zone offset. The way we do it is kind of 609 ** funny but it works. We loop through different time zones (0 to 24) and 610 ** pick the one that gives the smallest error (+- one half hour). The time 611 ** zone offset is stored in the datum_pts structure for future use. Normally, 612 ** the clocktime() routine is only called once (unless the time zone offset 613 ** changes due to daylight savings) since the goodtime flag is set when a 614 ** good time is found (with a good offset). Note that even if the Datum 615 ** PTS is using GMT, this mechanism will still work since it should come up 616 ** with a value for tzoff = 0 (assuming that your system clock is within 617 ** a half hour of the Datum time (even with time zone differences). 618 */ 619 620 for (tzoff=0; tzoff<24; tzoff++) { 621 if (clocktime( datum_pts->day, 622 datum_pts->hour, 623 datum_pts->minute, 624 datum_pts->second, 625 (tzoff + datum_pts->tzoff) % 24, 626 datum_pts->lastrec.l_ui, 627 &datum_pts->yearstart, 628 &datum_pts->lastref.l_ui) ) { 629 630 datum_pts->lastref.l_uf = 0; 631 error = datum_pts->lastref.l_ui - datum_pts->lastrec.l_ui; 632 633 #ifdef DEBUG_DATUM_PTC 634 printf("Time Zone (clocktime method) = %d, error = %d\n", tzoff, error); 635 #endif 636 637 if ((error < 1799) && (error > -1799)) { 638 tzoff = (tzoff + datum_pts->tzoff) % 24; 639 datum_pts->tzoff = tzoff; 640 goodtime = 1; 641 642 #ifdef DEBUG_DATUM_PTC 643 printf("Time Zone found (clocktime method) = %d\n",tzoff); 644 #endif 645 646 break; 647 } 648 649 } 650 } 651 652 #endif 653 654 /* 655 ** Make sure that we have a good time from the Datum PTS. Clocktime() also 656 ** sets yearstart and lastref.l_ui. We will have to set astref.l_uf (i.e., 657 ** the fraction of a second) stuff later. 658 */ 659 660 if (!goodtime) { 661 662 if (!clocktime( datum_pts->day, 663 datum_pts->hour, 664 datum_pts->minute, 665 datum_pts->second, 666 tzoff, 667 datum_pts->lastrec.l_ui, 668 &datum_pts->yearstart, 669 &datum_pts->lastref.l_ui) ) { 670 671 #ifdef DEBUG_DATUM_PTC 672 if (debug) 673 { 674 printf("Error: bad clocktime\n"); 675 printf("GMT %d, lastrec %d, yearstart %d, lastref %d\n", 676 tzoff, 677 datum_pts->lastrec.l_ui, 678 datum_pts->yearstart, 679 datum_pts->lastref.l_ui); 680 } 681 #endif 682 683 msyslog(LOG_ERR, "Datum_PTS: Bad clocktime"); 684 685 return; 686 687 }else{ 688 689 #ifdef DEBUG_DATUM_PTC 690 if (debug) 691 printf("Good clocktime\n"); 692 #endif 693 694 } 695 696 } 697 698 /* 699 ** We have datum_pts->lastref.l_ui set (which is the integer part of the 700 ** time. Now set the microseconds field. 701 */ 702 703 TVUTOTSF(datum_pts->usec, datum_pts->lastref.l_uf); 704 705 /* 706 ** Compute the time correction as the difference between the reference 707 ** time (i.e., the Datum time) minus the receive time (system time). 708 */ 709 710 tstmp = datum_pts->lastref; /* tstmp is the datum ntp time */ 711 L_SUB(&tstmp, &datum_pts->lastrec); /* tstmp is now the correction */ 712 datum_pts->coderecv++; /* increment a counter */ 713 714 #ifdef DEBUG_DATUM_PTC 715 dispersion = DATUM_DISPERSION; /* set the dispersion to 0 */ 716 ftimerr = dispersion; 717 ftimerr /= (1024.0 * 64.0); 718 if (debug) 719 printf("dispersion = %d, %f\n", dispersion, ftimerr); 720 #endif 721 722 /* 723 ** Pass the new time to ntpd through the refclock_receive function. Note 724 ** that we are not trying to make any corrections due to the time it takes 725 ** for the Datum PTS to send the message back. I am (erroneously) assuming 726 ** that the time for the Datum PTS to send the time back to us is negligable. 727 ** I suspect that this time delay may be as much as 15 ms or so (but probably 728 ** less). For our needs at JPL, this kind of error is ok so it is not 729 ** necessary to use fudge factors in the ntp.conf file. Maybe later we will. 730 */ 731 /*LFPTOD(&tstmp, doffset);*/ 732 datum_pts->lastref = datum_pts->lastrec; 733 refclock_receive(datum_pts->peer); 734 735 /* 736 ** Compute sigma squared (not used currently). Maybe later, this could be 737 ** used for the dispersion estimate. The problem is that ntpd does not link 738 ** in the math library so sqrt() is not available. Anyway, this is useful 739 ** for debugging. Maybe later I will just use absolute values for the time 740 ** error to come up with my dispersion estimate. Anyway, for now my dispersion 741 ** is set to 0. 742 */ 743 744 timerr = tstmp.l_ui<<20; 745 timerr |= (tstmp.l_uf>>12) & 0x000fffff; 746 ftimerr = timerr; 747 ftimerr /= 1024*1024; 748 abserr = ftimerr; 749 if (ftimerr < 0.0) abserr = -ftimerr; 750 751 if (datum_pts->sigma2 == 0.0) { 752 if (abserr < DATUM_MAX_ERROR) { 753 datum_pts->sigma2 = abserr*abserr; 754 }else{ 755 datum_pts->sigma2 = DATUM_MAX_ERROR2; 756 } 757 }else{ 758 if (abserr < DATUM_MAX_ERROR) { 759 datum_pts->sigma2 = 0.95*datum_pts->sigma2 + 0.05*abserr*abserr; 760 }else{ 761 datum_pts->sigma2 = 0.95*datum_pts->sigma2 + 0.05*DATUM_MAX_ERROR2; 762 } 763 } 764 765 #ifdef DEBUG_DATUM_PTC 766 if (debug) 767 printf("Time error = %f seconds\n", ftimerr); 768 #endif 769 770 #if defined(DEBUG_DATUM_PTC) || defined(LOG_TIME_ERRORS) 771 if (debug) 772 printf("PTS: day %d, hour %d, minute %d, second %d, msec %d, Time Error %f\n", 773 datum_pts->day, 774 datum_pts->hour, 775 datum_pts->minute, 776 datum_pts->second, 777 datum_pts->msec, 778 ftimerr); 779 #endif 780 781 } 782 #else 783 NONEMPTY_TRANSLATION_UNIT 784 #endif /* REFCLOCK */ 785