2 * Copyright (c) 2005 The DragonFly Project. All rights reserved.
4 * This code is derived from software contributed to The DragonFly Project
5 * by Matthew Dillon <dillon@backplane.com>
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions
11 * 1. Redistributions of source code must retain the above copyright
12 * notice, this list of conditions and the following disclaimer.
13 * 2. Redistributions in binary form must reproduce the above copyright
14 * notice, this list of conditions and the following disclaimer in
15 * the documentation and/or other materials provided with the
17 * 3. Neither the name of The DragonFly Project nor the names of its
18 * contributors may be used to endorse or promote products derived
19 * from this software without specific, prior written permission.
21 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
22 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
23 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
24 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
25 * COPYRIGHT HOLDERS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
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27 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
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29 * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
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34 * $DragonFly: src/usr.sbin/dntpd/system.c,v 1.1 2005/04/24 02:36:50 dillon Exp $
38 #include <sys/sysctl.h>
41 sysntp_getbasetime(struct timeval *tvp)
48 error = sysctlbyname("kern.basetime", &ts, &ts_size, NULL, 0);
50 logerr("sysctlbyname(\"kern.basetime\") failed, cannot continue");
57 * The offset error is passed as seconds per second.
59 * The 64 bit delta is calculated as nanoseconds per second. Since we are
60 * passed an offset error we must negate the result to correct the error.
62 * Because offset corrections skew the accuracy of the clock while the
63 * correction is in progress, we do not want to use them once we are
64 * reasonably well synchronized. We can make small offset corrections
65 * by shifting the frequency a bit. XXX
68 sysntp_correct_offset(double offset)
75 if (offset < -0.001 || offset > 0.001) {
77 fprintf(stderr, "issuing offset adjustment: %7.6f\n", -offset);
78 delta = -(int64_t)(offset * 1.0E+9);
79 sysctlbyname("kern.ntp.delta", NULL, 0, &delta, sizeof(delta));
84 * Fine correction - do it by adjusting the frequency.
91 * freq is passed as seconds per second.
93 * The calculated 64 bit correction is nanoseconds per second shifted
96 * Frequency errors greater then 1 second per second will not be corrected.
97 * It doesn't hurt to continue correcting the frequency.
100 sysntp_correct_freq(double freq)
104 if (freq >= -1.0 && freq < 1.0) {
106 fprintf(stderr, "issuing frequency adjustment: %6.3fppm\n",
109 delta = -((int64_t)(freq * 1.0E+9) << 32);
110 sysctlbyname("kern.ntp.permanent", NULL, 0, &delta, sizeof(delta));