int dofilter = 0; /* set to 1 when we should run filter algorithm */
int showtimes = 0; /* set to 1 when we should show char arrival times */
int doprocess = 0; /* set to 1 when we do processing analogous to driver */
#ifdef CHULDISC
int usechuldisc = 0; /* set to 1 when CHU line discipline should be used */
#endif
#ifdef STREAM
int usechuldisc = 0; /* set to 1 when CHU line discipline should be used */
#endif
struct timeval lasttv;
struct chucode chudata;
void error(char *fmt, char *s1, char *s2);
void init_chu(void);
int openterm(char *dev);
int process_raw(int s);
int process_ldisc(int s);
void raw_filter(unsigned int c, struct timeval *tv);
void chufilter(struct chucode *chuc, l_fp *rtime);
/*
* main - parse arguments and handle options
*/
int
main(
int argc,
char *argv[]
)
{
int c;
int errflg = 0;
extern int ntp_optind;
progname = argv[0];
while ((c = ntp_getopt(argc, argv, "cdfpt")) != EOF)
switch (c) {
case 'c':
#ifdef STREAM
usechuldisc = 1;
break;
#endif
#ifdef CHULDISC
usechuldisc = 1;
break;
#endif
#ifndef STREAM
#ifndef CHULDISC
(void) fprintf(stderr,
"%s: CHU line discipline not available on this machine\n",
progname);
exit(2);
#endif
#endif
case 'd':
++debug;
break;
case 'f':
dofilter = 1;
break;
case 'p':
doprocess = 1;
case 't':
showtimes = 1;
break;
default:
errflg++;
break;
}
if (errflg || ntp_optind+1 != argc) {
#ifdef STREAM
(void) fprintf(stderr, "usage: %s [-dft] tty_device\n",
progname);
#endif
#ifdef CHULDISC
(void) fprintf(stderr, "usage: %s [-dft] tty_device\n",
progname);
#endif
#ifndef STREAM
#ifndef CHULDISC
(void) fprintf(stderr, "usage: %s [-cdft] tty_device\n",
progname);
#endif
#endif
exit(2);
}
(void) gettimeofday(&lasttv, (struct timezone *)0);
c = openterm(argv[ntp_optind]);
init_chu();
#ifdef STREAM
if (usechuldisc)
process_ldisc(c);
else
#endif
#ifdef CHULDISC
if (usechuldisc)
process_ldisc(c);
else
#endif
process_raw(c);
/*NOTREACHED*/
}
/*
* openterm - open a port to the CHU clock
*/
int
openterm(
char *dev
)
{
int s;
struct sgttyb ttyb;
if (debug)
(void) fprintf(stderr, "Doing open...");
if ((s = open(dev, O_RDONLY, 0777)) < 0)
error("open(%s)", dev, "");
if (debug)
(void) fprintf(stderr, "open okay\n");
if (debug)
(void) fprintf(stderr, "Setting exclusive use...");
if (ioctl(s, TIOCEXCL, (char *)0) < 0)
error("ioctl(TIOCEXCL)", "", "");
if (debug)
(void) fprintf(stderr, "done\n");
ttyb.sg_ispeed = ttyb.sg_ospeed = B300;
ttyb.sg_erase = ttyb.sg_kill = 0;
ttyb.sg_flags = EVENP|ODDP|RAW;
if (debug)
(void) fprintf(stderr, "Setting baud rate et al...");
if (ioctl(s, TIOCSETP, (char *)&ttyb) < 0)
error("ioctl(TIOCSETP, raw)", "", "");
if (debug)
(void) fprintf(stderr, "done\n");
#ifdef CHULDISC
if (usechuldisc) {
int ldisc;
if (debug)
(void) fprintf(stderr, "Switching to CHU ldisc...");
ldisc = CHULDISC;
if (ioctl(s, TIOCSETD, (char *)&ldisc) < 0)
error("ioctl(TIOCSETD, CHULDISC)", "", "");
if (debug)
(void) fprintf(stderr, "okay\n");
}
#endif
#ifdef STREAM
if (usechuldisc) {
if (debug)
(void) fprintf(stderr, "Poping off streams...");
while (ioctl(s, I_POP, 0) >=0) ;
if (debug)
(void) fprintf(stderr, "okay\n");
if (debug)
(void) fprintf(stderr, "Pushing CHU stream...");
if (ioctl(s, I_PUSH, "chu") < 0)
error("ioctl(I_PUSH, \"chu\")", "", "");
if (debug)
(void) fprintf(stderr, "okay\n");
}
#endif
return s;
}
/*
* process_raw - process characters in raw mode
*/
int
process_raw(
int s
)
{
u_char c;
int n;
struct timeval tv;
struct timeval difftv;
if (n == 0) {
(void) fprintf(stderr, "%s: zero returned on read\n", progname);
exit(1);
} else
error("read()", "", "");
}
/*
* raw_filter - run the line discipline filter over raw data
*/
void
raw_filter(
unsigned int c,
struct timeval *tv
)
{
static struct timeval diffs[10];
struct timeval diff;
l_fp ts;
chudata.codechars[chudata.ncodechars] = c;
chudata.codetimes[chudata.ncodechars] = *tv;
if (chudata.ncodechars > 0)
diffs[chudata.ncodechars] = diff;
if (++chudata.ncodechars == 10) {
if (doprocess) {
TVTOTS(&chudata.codetimes[NCHUCHARS-1], &ts);
ts.l_ui += JAN_1970;
chufilter(&chudata, &chudata.codetimes[NCHUCHARS-1]);
} else {
register int i;
for (i = 0; i < chudata.ncodechars; i++) {
(void) printf("%x%x\t%lu.%06lu\t%lu.%06lu\n",
chudata.codechars[i] & 0xf,
(chudata.codechars[i] >>4 ) & 0xf,
chudata.codetimes[i].tv_sec,
chudata.codetimes[i].tv_usec,
diffs[i].tv_sec, diffs[i].tv_usec);
}
}
chudata.ncodechars = 0;
}
}
/* #ifdef CHULDISC*/
/*
* process_ldisc - process line discipline
*/
int
process_ldisc(
int s
)
{
struct chucode chu;
int n;
register int i;
struct timeval diff;
l_fp ts;
void chufilter();
/*
* Definitions
*/
#define MAXUNITS 4 /* maximum number of CHU units permitted */
#define CHUDEV "/dev/chu%d" /* device we open. %d is unit number */
#define NCHUCODES 9 /* expect 9 CHU codes per minute */
/*
* When CHU is operating optimally we want the primary clock distance
* to come out at 300 ms. Thus, peer.distance in the CHU peer structure
* is set to 290 ms and we compute delays which are at least 10 ms long.
* The following are 290 ms and 10 ms expressed in u_fp format
*/
#define CHUDISTANCE 0x00004a3d
#define CHUBASEDELAY 0x0000028f
/*
* To compute a quality for the estimate (a pseudo delay) we add a
* fixed 10 ms for each missing code in the minute and add to this
* the sum of the differences between the remaining offsets and the
* estimated sample offset.
*/
#define CHUDELAYPENALTY 0x0000028f
/*
* Other constant stuff
*/
#define CHUPRECISION (-9) /* what the heck */
#define CHUREFID "CHU\0"
/*
* Hacks to avoid excercising the multiplier. I have no pride.
*/
#define MULBY10(x) (((x)<<3) + ((x)<<1))
#define MULBY60(x) (((x)<<6) - ((x)<<2)) /* watch overflow */
#define MULBY24(x) (((x)<<4) + ((x)<<3))
/*
* Constants for use when multiplying by 0.1. ZEROPTONE is 0.1
* as an l_fp fraction, NZPOBITS is the number of significant bits
* in ZEROPTONE.
*/
#define ZEROPTONE 0x1999999a
#define NZPOBITS 29
/*
* The CHU table. This gives the expected time of arrival of each
* character after the on-time second and is computed as follows:
* The CHU time code is sent at 300 bps. Your average UART will
* synchronize at the edge of the start bit and will consider the
* character complete at the center of the first stop bit, i.e.
* 0.031667 ms later. Thus the expected time of each interrupt
* is the start bit time plus 0.031667 seconds. These times are
* in chutable[]. To this we add such things as propagation delay
* and delay fudge factor.
*/
#define CHARDELAY 0x081b4e80
/*
* Keep the fudge factors separately so they can be set even
* when no clock is configured.
*/
static l_fp propagation_delay;
static l_fp fudgefactor;
static l_fp offset_fudge;
/*
* We keep track of the start of the year, watching for changes.
* We also keep track of whether the year is a leap year or not.
* All because stupid CHU doesn't include the year in the time code.
*/
static u_long yearstart;
/*
* Imported from the timer module
*/
extern u_long current_time;
extern struct event timerqueue[];
void
chufilter(
struct chucode *chuc,
l_fp *rtime
)
{
register int i;
register u_long date_ui;
register u_long tmp;
register u_char *code;
int isneg;
int imin;
int imax;
u_long reftime;
l_fp off[NCHUCHARS];
l_fp ts;
int day, hour, minute, second;
static u_char lastcode[NCHUCHARS];
/*
* We'll skip the checks made in the kernel, but assume they've
* been done. This means that all characters are BCD and
* the intercharacter spacing isn't unreasonable.
*/
/*
* print the code
*/
for (i = 0; i < NCHUCHARS; i++)
printf("%c%c", (chuc->codechars[i] & 0xf) + '0',
((chuc->codechars[i]>>4) & 0xf) + '0');
printf("\n");
/*
* Format check. Make sure the two halves match.
*/
for (i = 0; i < NCHUCHARS/2; i++)
if (chuc->codechars[i] != chuc->codechars[i+(NCHUCHARS/2)]) {
(void) printf("Bad format, halves don't match\n");
return;
}
/*
* Break out the code into the BCD nibbles. Only need to fiddle
* with the first half since both are identical. Note the first
* BCD character is the low order nibble, the second the high order.
*/
code = lastcode;
for (i = 0; i < NCHUCHARS/2; i++) {
*code++ = chuc->codechars[i] & 0xf;
*code++ = (chuc->codechars[i] >> 4) & 0xf;
}
/*
* If the first nibble isn't a 6, we're up the creek
*/
code = lastcode;
if (*code++ != 6) {
(void) printf("Bad format, no 6 at start\n");
return;
}
/*
* Collect the day, the hour, the minute and the second.
*/
day = *code++;
day = MULBY10(day) + *code++;
day = MULBY10(day) + *code++;
hour = *code++;
hour = MULBY10(hour) + *code++;
minute = *code++;
minute = MULBY10(minute) + *code++;
second = *code++;
second = MULBY10(second) + *code++;
/*
* Sanity check the day and time. Note that this
* only occurs on the 31st through the 39th second
* of the minute.
*/
if (day < 1 || day > 366
|| hour > 23 || minute > 59
|| second < 31 || second > 39) {
(void) printf("Failed date sanity check: %d %d %d %d\n",
day, hour, minute, second);
return;
}
/*
* Now the fun begins. We demand that the received time code
* be within CLOCK_WAYTOOBIG of the receive timestamp, but
* there is uncertainty about the year the timestamp is in.
* Use the current year start for the first check, this should
* work most of the time.
*/
date_ui = tmp + yearstart;
#define CLOCK_WAYTOOBIG 1000 /* revived from ancient sources */
if (date_ui < (rtime->l_ui + CLOCK_WAYTOOBIG)
&& date_ui > (rtime->l_ui - CLOCK_WAYTOOBIG))
goto codeokay; /* looks good */
/*
* Trouble. Next check is to see if the year rolled over and, if
* so, try again with the new year's start.
*/
date_ui = calyearstart(rtime->l_ui, NULL);
if (date_ui != yearstart) {
yearstart = date_ui;
date_ui += tmp;
(void) printf("time %u, code %u, difference %d\n",
date_ui, rtime->l_ui, (long)date_ui-(long)rtime->l_ui);
if (date_ui < (rtime->l_ui + CLOCK_WAYTOOBIG)
&& date_ui > (rtime->l_ui - CLOCK_WAYTOOBIG))
goto codeokay; /* okay this time */
}
/*
* Here we know the year start matches the current system
* time. One remaining possibility is that the time code
* is in the year previous to that of the system time. This
* is only worth checking if the receive timestamp is less
* than CLOCK_WAYTOOBIG seconds into the new year.
*/
if ((rtime->l_ui - yearstart) < CLOCK_WAYTOOBIG) {
date_ui = tmp;
date_ui += calyearstart(yearstart - CLOCK_WAYTOOBIG,
NULL);
if ((rtime->l_ui - date_ui) < CLOCK_WAYTOOBIG)
goto codeokay;
}
/*
* One last possibility is that the time stamp is in the year
* following the year the system is in. Try this one before
* giving up.
*/
date_ui = tmp;
date_ui += calyearstart(yearstart + (400 * SECSPERDAY),
NULL);
if ((date_ui - rtime->l_ui) >= CLOCK_WAYTOOBIG) {
printf("Date hopelessly off\n");
return; /* hopeless, let it sync to other peers */
}
codeokay:
reftime = date_ui;
/*
* We've now got the integral seconds part of the time code (we hope).
* The fractional part comes from the table. We next compute
* the offsets for each character.
*/
for (i = 0; i < NCHUCHARS; i++) {
register u_long tmp2;
/*
* Here is a *big* problem. What one would normally
* do here on a machine with lots of clock bits (say
* a Vax or the gizmo board) is pick the most positive
* offset and the estimate, since this is the one that
* is most likely suffered the smallest interrupt delay.
* The trouble is that the low order clock bit on an IBM
* RT, which is the machine I had in mind when doing this,
* ticks at just under the millisecond mark. This isn't
* precise enough. What we can do to improve this is to
* average all 10 samples and rely on the second level
* filtering to pick the least delayed estimate. Trouble
* is, this means we have to divide a 64 bit fixed point
* number by 10, a procedure which really sucks. Oh, well.
* First compute the sum.
*/
date_ui = 0;
tmp = 0;
for (i = 0; i < NCHUCHARS; i++)
M_ADD(date_ui, tmp, off[i].l_ui, off[i].l_uf);
if (M_ISNEG(date_ui, tmp))
isneg = 1;
else
isneg = 0;
/*
* Here is a multiply-by-0.1 optimization that should apply
* just about everywhere. If the magnitude of the sum
* is less than 9 we don't have to worry about overflow
* out of a 64 bit product, even after rounding.
*/
if (date_ui < 9 || date_ui > 0xfffffff7) {
register u_long prod_ui;
register u_long prod_uf;
prod_ui = prod_uf = 0;
/*
* This code knows the low order bit in 0.1 is zero
*/
for (i = 1; i < NZPOBITS; i++) {
M_LSHIFT(date_ui, tmp);
if (ZEROPTONE & (1<<i))
M_ADD(prod_ui, prod_uf, date_ui, tmp);
}
/*
* Done, round it correctly. Prod_ui contains the
* fraction.
*/
if (prod_uf & 0x80000000)
prod_ui++;
if (isneg)
date_ui = 0xffffffff;
else
date_ui = 0;
tmp = prod_ui;
/*
* date_ui is integral part, tmp is fraction.
*/
} else {
register u_long prod_ovr;
register u_long prod_ui;
register u_long prod_uf;
register u_long highbits;
prod_ovr = prod_ui = prod_uf = 0;
if (isneg)
highbits = 0xffffffff; /* sign extend */
else
highbits = 0;
/*
* This code knows the low order bit in 0.1 is zero
*/
for (i = 1; i < NZPOBITS; i++) {
M_LSHIFT3(highbits, date_ui, tmp);
if (ZEROPTONE & (1<<i))
M_ADD3(prod_ovr, prod_uf, prod_ui,
highbits, date_ui, tmp);
}
/*
* At this point we have the mean offset, with the integral
* part in date_ui and the fractional part in tmp. Store
* it in the structure.
*/
/*
* Add in fudge factor.
*/
M_ADD(date_ui, tmp, offset_fudge.l_ui, offset_fudge.l_uf);
/*
* Find the minimun and maximum offset
*/
imin = imax = 0;
for (i = 1; i < NCHUCHARS; i++) {
if (L_ISGEQ(&off[i], &off[imax])) {
imax = i;
} else if (L_ISGEQ(&off[imin], &off[i])) {
imin = i;
}
}
L_ADD(&off[imin], &offset_fudge);
if (imin != imax)
L_ADD(&off[imax], &offset_fudge);
(void) printf("mean %s, min %s, max %s\n",
mfptoa(date_ui, tmp, 8), lfptoa(&off[imin], 8),
lfptoa(&off[imax], 8));
}
