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Path: utzoo!mnetor!uunet!lll-winken!csustan!helium!scott
From: scott@helium.UUCP (Scott Hazen Mueller)
Newsgroups: comp.unix.xenix
Subject: uPort V/386 h/w clock
Message-ID: <222@helium.UUCP>
Date: Mon, 19-Oct-87 18:10:44 EDT
Article-I.D.: helium.222
Posted: Mon Oct 19 18:10:44 1987
Date-Received: Tue, 20-Oct-87 23:48:35 EDT
Reply-To: scott@helium.UUCP (Scott Hazen Mueller)
Organization: City of Turlock, CA
Lines: 89
Keywords: program, small, set h/w clock
Summary: a program

For whatever reason, it's not possible to set the AT(-style) hardware clock
on a Microport V/386 system from Unix.  In other words, you've got to boot
the MsDos setup disk in order to reset the h/w clock, and if you're like me,
your built-in clock loses time and your system (software) clock gains time.
Not a pretty situation, nor terribly robust.  Unfortunately for me, the
support person at Microport seems to have been having a bit of difficulty
with the notion of there being two clocks, both of which are wrong.  So, I've
not been able to get them to admit to the existence of a clock setter; given
that, I just decided that I would poke around the /usr/include directory
until I figured out a little about what's going on.  Here's a little hackish
program to throw some settings into the clock, then.

Please note that I'm giving away all rights, such as they are, and have no
intentions of supporting this thing (not as a private citizen, anyway -
anybody wanna hire me? :-) though I'm obviously willing to junk it if it
proves to be a) dangerous or b) superfluous.

Program follows.

         \scott
----- Snip snip -----
/* Set hardware clock.  Input format is on the command line; e.g.

stime <year> <month> <day> <hour> <minute>

with white space separating the arguments (that is, don't concatenate them
into one big schlurg...).  Or, for the perverse the command

stime `date '+ %y %m %d %H %M'`

can be used.  This assumes that your s/w clock is more correct.  Since in
my case, both are usually wrong, I'll keep it simple.

Oh, yeah:  this was written under Microport System V/386, release 1.0.  It
probably won't work under V/AT; it may or may not work on other derivatives
of Interactive's port of System V to the 80386.

                 *****     NO ERROR CHECKING     *****

Scott Hazen Mueller   City of Turlock    901 S. Walnut Rd.  Turlock CA 95380
(209) 668-5590        lll-crg!csustan!helium!scott   uunet!zorch!helium!scott

Disclaimer:  this is *free*; I'm giving it away, hoping to stir someone with
some documentation into writing a real program, with error-checking and all.
I hereby release this program into the public domain and disclaim its fitness
for any purpose whatsoever.  Use at your own risk.

*/

#include <fcntl.h>
#include <sys/rtc.h>

main( argc, argv )
int argc;
char *argv[];
{
char buf[80];				/*	Overkill	*/
int  cd, i;

cd = open( "/dev/rtc", O_RDONLY );

/* This is the way these locations were when I first read them.  They
probably do neat stuff like set daylight savings mode and such.  It'd be
nice if they were documented.	*/

buf[0] = 0x0; buf[1] = buf[3] = buf[5] = 1; buf[6] = 6;

/* This is gross and disgusting.  For some reason, the time values to be
set are hex dates.  That is, if it's October, and you print the month in
decimal, you get '16', but if you use a hex format you get '10'.  What I've
got to do, then, is scan off the args in hex and stuff them into character-
sized locations.  There's probably a better way; what do you expect for
free?	*/

sscanf( argv[1], "%x", &i ); buf[9] |= i;
sscanf( argv[2], "%x", &i ); buf[8] |= i;
sscanf( argv[3], "%x", &i ); buf[7] |= i;
sscanf( argv[4], "%x", &i ); buf[4] |= i;
sscanf( argv[5], "%x", &i ); buf[2] |= i;

/* The year had all of this crud; I dunno why.  Real easy to mask it in,
though.  */

buf[9] |= 0xffffff00;

/* Once you've gotten this far, the actual work is trivially simple.  */

ioctl( cd, RTCSTIME, buf );
close( cd );
}