getty speed switching under Ultrix v1.2

[Chris Torek]

In article <2996 at brl-smoke.ARPA> iglesias at ICS.UCI.EDU (Mike Iglesias) writes:
>I've set up /etc/gettytab on our Microvax II running Ultrix v1.2 to
>switch line speeds on breaks.  However, it doesn't seem to be very
>reliable.  It appears that Ultrix is seeing one break as several, so
>it skips past the correct speed about half the time. ...

Well, if you have source (this is one reason everyone should insist
on source!) you can fix it yourself.  If not, perhaps you can
convince DEC to do it for you.  The `fix' is to use a different
method entirely:  We auto-baud on carriage returns.  The code
below is for 4.3BSD, but should be easy to convert to 4.2 or Ultrix.

Another possible fix is to add a `sleep(2)' (or so) and a line
flush (if necessary) after detecting a break.

==> /usr/src/etc/getty/subr.c
RCS file: RCS/subr.c,v
retrieving revision 1.1
diff -c2 -r1.1 subr.c
*** /tmp/,RCSt1017315	Thu Aug 14 10:14:34 1986
--- subr.c	Sat Oct  5 06:40:21 1985
***************
*** 417,420 ****
--- 417,422 ----
  }
  
+ #ifdef notdef
+ 
  /*
   * This auto-baud speed select mechanism is written for the Micom 600
***************
*** 469,470 ****
--- 471,608 ----
  	return (type);
  }
+ 
+ #else
+ 
+ /*
+  * Try to figure out what speed the terminal is set to based on what
+  * a carriage-return or newline looks like at 2400 baud.  5/18/82 FLB
+  *
+  * N.B.: some of the table entries for \n collide with those for \r.
+  * Only the first one in the table will be matched.
+  */
+ 
+ #include <sys/types.h>
+ #include <sys/time.h>
+ #include <signal.h>
+ #include <setjmp.h>
+ 
+ struct autobaud {
+ 	char *s_speed;
+ 	char *s_string;		/* first byte is length */
+ } a_tab[] = {
+ 	/* carriage-return */
+ 	"110-baud",	"\3\000\000\000",	/* also \n */
+ 	"300-baud",	"\3\200\200\000",	/* collides with 600 \n */
+ 	"300-baud",	"\3\200\000\000",
+ 	"300-baud",	"\3\000\200\000",	/* also \n */
+ 	"600-baud",	"\3\000\376\000",
+ 	"1200-baud",	"\2\346\200",
+ 	"1200-baud",	"\2\346\340",
+ 	"1200-baud",	"\2\367\300",
+ 	"1800-baud",	"\2\000\376",		/* also \n */
+ 	"1800-baud",	"\2\000\377",
+ 	"2400-baud",	"\1\015",
+ 	"2400-baud",	"\1\215",
+ 	"4800-baud",	"\1\361",		/* needed for Gandalf */
+ 	"4800-baud",	"\1\362",
+ 	"4800-baud",	"\1\363",		/* needed for Gandalf */
+ 	"4800-baud",	"\1\371",		/* needed for Gandalf */
+ 	"4800-baud",	"\1\375",		/* needed for Gandalf */
+ 	"4800-baud",	"\1\376",		/* needed for Gandalf;
+ 						   collides with 9600 \n */
+ 	"9600-baud",	"\1\377",		/* needed for Gandalf */
+ 
+ 	/* newline */
+ 	"600-baud",	"\3\200\000\000",	/* collides with 300 \r */
+ 	"1200-baud",	"\2\230\200",
+ 	"2400-baud",	"\1\012",
+ 	"4800-baud",	"\1\370",
+ 	"9600-baud",	"\1\376",		/* collides with 4800 \r */
+ 
+ 	/* The next entry must be the last entry in the table. */
+ 	0,		"\1\0",			/* BREAK: handled specially */
+ 
+ 	0,		0
+ };
+ 
+ char *
+ autobaud()
+ {
+ 	register struct autobaud *tp;
+ 	register int i;
+ 	struct sgttyb ttyb;
+ 	static char buf[10];
+ 
+ 	extern jmp_buf timeout;	/* from main.c */
+ 	extern int dingdong();	/* from main.c */
+ 
+ 	if (TO) {
+ 		if (setjmp(timeout)) {
+ 			/*
+ 			 * Drop DTR for a while.  This is important
+ 			 * for Gandalf lines which must be told to
+ 			 * disconnect.
+ 			 */
+ 			ttyb.sg_ispeed = ttyb.sg_ospeed = 0;
+ 			(void) ioctl(0, TIOCSETP, &ttyb);
+ 			sleep(3);
+ 			exit(1);
+ 		}
+ 		signal(SIGALRM, dingdong);
+ 		alarm(TO);
+ 	}
+ 
+ 	/*
+ 	 * The following hack sets BREAK to sequence to the next
+ 	 * gettytab entry.
+ 	 */
+ 	a_tab[(sizeof (a_tab) / sizeof (a_tab[0])) - 2].s_speed =
+ 	    NX && *NX ? NX : 0;
+ 
+ 	ttyb.sg_ispeed = ttyb.sg_ospeed = B2400;
+ 	ttyb.sg_flags = ANYP|RAW;
+ 
+ 	for (;;) {
+ 		(void) ioctl(0, TIOCSETP, &ttyb);
+ 		input(buf, sizeof buf);
+ 
+ 		for (tp = a_tab; tp->s_speed; tp++) {
+ 			for (i = 0;; i++) {
+ 				if (buf[i] != tp->s_string[i])
+ 					break;
+ 				if (i == buf[0]) {
+ 					alarm(0);
+ 					return (tp->s_speed);
+ 				}
+ 			}
+ 		}
+ 	}
+ 	/*NOTREACHED*/
+ }
+ 
+ input(s, n)
+ 	char *s;
+ 	register int n;
+ {
+ 	register char *cp = s + 1;
+ 	fd_set rfds;
+ 	struct timeval timeout;
+ 
+ 	FD_ZERO(&rfds);
+ 	FD_SET(0, &rfds);
+ 	timeout.tv_sec = 0;	/* .15 seconds */
+ 	timeout.tv_usec = 150000;
+ 	n--;			/* first byte is for length */
+ 	(void) read(0, cp, 1);	/* wait for something */
+ 	n--, cp++;
+ 	while (--n >= 0) {
+ 		if (select(1, &rfds, (fd_set *)0, (fd_set *)0, &timeout) <= 0)
+ 			break;
+ 		if (read(0, cp, 1) != 1)
+ 			break;
+ 		cp++;
+ 	}
+ 	*s = (cp - s) - 1;
+ }
+ 
+ #endif
-- 
In-Real-Life: Chris Torek, Univ of MD Comp Sci Dept (+1 301 454 1516)
UUCP:	seismo!umcp-cs!chris
CSNet:	chris at umcp-cs		ARPA:	chris at mimsy.umd.edu