xntpd 3.3b from UDel

[unix-history] / contrib / xntpd / util / timetrim.c

/*
* timetrim.c,v 3.1 1993/07/06 01:11:06 jbj Exp
* 
* "timetrim" allows setting and adjustment of the system clock frequency
* trim parameter on Silicon Graphics machines.  The trim value native
* units are nanoseconds per second (10**-9), so a trim value of 1 makes
* the system clock step ahead 1 nanosecond more per second than a value
* of zero.  Xntpd currently uses units of 2**-20 secs for its frequency
* offset (drift) values; to convert to a timetrim value, multiply by
* 1E9 / 2**20 (about 954).
* 
* "timetrim" with no arguments just prints out the current kernel value.
* With a numeric argument, the kernel value is set to the supplied value.
* The "-i" flag causes the supplied value to be added to the kernel value.
* The "-n" option causes all input and output to be in xntpd units rather
* than timetrim native units.
*
* Note that there is a limit of +-3000000 (0.3%) on the timetrim value
* which is (silently?) enforced by the kernel.
* 
*/

#include <stdio.h>
#include <ctype.h>
#include <sys/syssgi.h>

#define abs(X) (((X) < 0) ? -(X) : (X))
#define USAGE "usage: timetrim [-n] [[-i] value]\n"
#define SGITONTP(X) ((double)(X) * 1048576.0/1.0e9)
#define NTPTOSGI(X) ((LONG)((X) * 1.0e9/1048576.0))

main(argc, argv)
int argc;
char **argv;
{
       char *rem;
       int c, incremental = 0, ntpunits = 0;
       LONG timetrim;
       double value, strtod();
       
       while (--argc && **++argv == '-' && isalpha(argv[0][1])) {
               switch (argv[0][1]) {
               case 'i':
                       incremental++;
                       break;
               case 'n':
                       ntpunits++;
                       break;
               default:
                       fprintf(stderr, USAGE);
                       exit(1);
               }
       }

       if (syssgi(SGI_GETTIMETRIM, &timetrim) < 0) {
               perror("syssgi");
               exit(2);
       }

       if (argc == 0) {
               if (ntpunits)
                       fprintf(stdout, "%0.5lf\n", SGITONTP(timetrim));
               else
                       fprintf(stdout, "%ld\n", timetrim);
       } else if (argc != 1) {
               fprintf(stderr, USAGE);
               exit(1);
       } else {
               value = strtod(argv[0], &rem);
               if (*rem != '\0') {
                       fprintf(stderr, USAGE);
                       exit(1);
               }
               if (ntpunits)
                       value = NTPTOSGI(value);
               if (incremental)
                       timetrim += value;
               else
                       timetrim = value;
               if (syssgi(SGI_SETTIMETRIM, timetrim) < 0) {
                       perror("syssgi");
                       exit(2);
               }
       }
}