File: refclock_shm.c

package info (click to toggle)
chrony 3.0-4+deb9u2
  • links: PTS, VCS
  • area: main
  • in suites: stretch
  • size: 2,496 kB
  • sloc: ansic: 23,531; sh: 2,022; yacc: 866; makefile: 195
file content (133 lines) | stat: -rw-r--r-- 3,644 bytes parent folder | download
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
/*
  chronyd/chronyc - Programs for keeping computer clocks accurate.

 **********************************************************************
 * Copyright (C) Miroslav Lichvar  2009
 * 
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of version 2 of the GNU General Public License as
 * published by the Free Software Foundation.
 * 
 * This program is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * General Public License for more details.
 * 
 * You should have received a copy of the GNU General Public License along
 * with this program; if not, write to the Free Software Foundation, Inc.,
 * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
 * 
 **********************************************************************

  =======================================================================

  SHM refclock driver.

  */

#include "config.h"

#include "sysincl.h"

#include "refclock.h"
#include "logging.h"
#include "util.h"

#define SHMKEY 0x4e545030

struct shmTime {
  int    mode; /* 0 - if valid set
                *       use values, 
                *       clear valid
                * 1 - if valid set 
                *       if count before and after read of values is equal,
                *         use values 
                *       clear valid
                */
  volatile int count;
  time_t clockTimeStampSec;
  int    clockTimeStampUSec;
  time_t receiveTimeStampSec;
  int    receiveTimeStampUSec;
  int    leap;
  int    precision;
  int    nsamples;
  volatile int valid;
  int    clockTimeStampNSec;
  int    receiveTimeStampNSec;
  int    dummy[8]; 
};

static int shm_initialise(RCL_Instance instance) {
  int id, param, perm;
  char *s;
  struct shmTime *shm;

  param = atoi(RCL_GetDriverParameter(instance));
  s = RCL_GetDriverOption(instance, "perm");
  perm = s ? strtol(s, NULL, 8) & 0777 : 0600;

  id = shmget(SHMKEY + param, sizeof (struct shmTime), IPC_CREAT | perm);
  if (id == -1) {
    LOG_FATAL(LOGF_Refclock, "shmget() failed");
    return 0;
  }
   
  shm = (struct shmTime *)shmat(id, 0, 0);
  if ((long)shm == -1) {
    LOG_FATAL(LOGF_Refclock, "shmat() failed");
    return 0;
  }

  RCL_SetDriverData(instance, shm);
  return 1;
}

static void shm_finalise(RCL_Instance instance)
{
  shmdt(RCL_GetDriverData(instance));
}

static int shm_poll(RCL_Instance instance)
{
  struct timespec receive_ts, clock_ts;
  struct shmTime t, *shm;
  double offset;

  shm = (struct shmTime *)RCL_GetDriverData(instance);

  t = *shm;
  
  if ((t.mode == 1 && t.count != shm->count) ||
    !(t.mode == 0 || t.mode == 1) || !t.valid) {
    DEBUG_LOG(LOGF_Refclock, "SHM sample ignored mode=%d count=%d valid=%d",
        t.mode, t.count, t.valid);
    return 0;
  }

  shm->valid = 0;

  receive_ts.tv_sec = t.receiveTimeStampSec;
  clock_ts.tv_sec = t.clockTimeStampSec;

  if (t.clockTimeStampNSec / 1000 == t.clockTimeStampUSec &&
      t.receiveTimeStampNSec / 1000 == t.receiveTimeStampUSec) {
    receive_ts.tv_nsec = t.receiveTimeStampNSec;
    clock_ts.tv_nsec = t.clockTimeStampNSec;
  } else {
    receive_ts.tv_nsec = 1000 * t.receiveTimeStampUSec;
    clock_ts.tv_nsec = 1000 * t.clockTimeStampUSec;
  }

  UTI_NormaliseTimespec(&clock_ts);
  UTI_NormaliseTimespec(&receive_ts);
  offset = UTI_DiffTimespecsToDouble(&clock_ts, &receive_ts);

  return RCL_AddSample(instance, &receive_ts, offset, t.leap);
}

RefclockDriver RCL_SHM_driver = {
  shm_initialise,
  shm_finalise,
  shm_poll
};