timetrim.c

网络时间协议NTP 源码 版本v4.2.0b 该源码用于linux平台下

#if defined(sgi) || defined(_UNICOSMP)
/*
 * timetrim.c
 * 
 * "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.
 * 
 */

#ifdef HAVE_CONFIG_H
#include <config.h>
#endif

#include <stdio.h>
#include <ctype.h>
#include <stdlib.h>
#ifdef HAVE_SYS_SYSSGI_H
# include <sys/syssgi.h>
#endif
#ifdef HAVE_SYS_SYSTUNE_H
# include <sys/systune.h>
#endif

#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))

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

#ifdef HAVE_SYS_SYSSGI_H
	if (syssgi(SGI_GETTIMETRIM, &timetrim) < 0) {
		perror("syssgi");
		exit(2);
	}
#endif
#ifdef HAVE_SYS_SYSTUNE_H
	if (systune(SYSTUNE_GET, "timetrim", &timetrim) < 0) {
		perror("systune");
		exit(2);
	}
#endif

	if (argc == 0) {
		if (ntpunits)
		    fprintf(stdout, "%0.5f\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;
#ifdef HAVE_SYS_SYSSGI_H
		if (syssgi(SGI_SETTIMETRIM, timetrim) < 0) {
			perror("syssgi");
			exit(2);
		}
#endif
#ifdef HAVE_SYS_SYSTUNE_H
		if (systune(SYSTUNE_SET, "timer", "timetrim", &timetrim) < 0) {
			perror("systune");
			exit(2);
		}
#endif
	}
	return 0;
}
#endif