2 * Copyright 2000, International Business Machines Corporation and others.
5 * This software has been released under the terms of the IBM Public
6 * License. For details, see the LICENSE file in the top-level source
7 * directory or online at http://www.openafs.org/dl/license10.html
10 /* Elapsed time package */
11 /* See rx_clock.h for calling conventions */
13 #include <afsconfig.h>
14 #include "afs/param.h"
17 #include <sys/time_impl.h>
25 # include "afs/sysincludes.h"
26 # include "afsincludes.h"
27 # endif /* !UKERNEL */
29 # include <sys/time.h>
41 #if !defined(AFS_USE_GETTIMEOFDAY)
42 /*use this package only if gettimeofday is much much costlier than getitime */
46 #define STARTVALUE 3600
47 static struct clock startvalue;
48 static struct clock relclock_epoch; /* The elapsed time of the last itimer reset */
50 struct clock clock_now; /* The last elapsed time ready by clock_GetTimer */
52 /* This is set to 1 whenever the time is read, and reset to 0 whenever clock_NewTime is called. This is to allow the caller to control the frequency with which the actual time is re-evaluated (an expensive operation) */
53 int clock_haveCurrentTime;
55 int clock_nUpdates; /* The actual number of clock updates */
56 static int clockInitialized = 0;
61 struct itimerval itimer, otimer;
62 itimer.it_value.tv_sec = STARTVALUE;
63 itimer.it_value.tv_usec = 0;
64 itimer.it_interval.tv_sec = 0;
65 itimer.it_interval.tv_usec = 0;
67 signal(SIGALRM, SIG_IGN);
68 if (setitimer(ITIMER_REAL, &itimer, &otimer) != 0) {
69 osi_Panic("clock: could not set interval timer; aborted(errno=%d)\n",
72 if (relclock_epoch.usec + startvalue.usec >= otimer.it_value.tv_usec) {
73 relclock_epoch.sec = relclock_epoch.sec +
74 startvalue.sec - otimer.it_value.tv_sec;
75 relclock_epoch.usec = relclock_epoch.usec +
76 startvalue.usec - otimer.it_value.tv_usec;
78 relclock_epoch.sec = relclock_epoch.sec +
79 startvalue.sec - 1 - otimer.it_value.tv_sec;
80 relclock_epoch.usec = relclock_epoch.usec +
81 startvalue.usec + 1000000 - otimer.it_value.tv_usec;
83 if (relclock_epoch.usec >= 1000000)
84 relclock_epoch.usec -= 1000000, relclock_epoch.sec++;
85 /* the initial value of the interval timer may not be exactly the same
86 * as the arg passed to setitimer. POSIX allows the implementation to
87 * round it up slightly, and some nonconformant implementations truncate
89 getitimer(ITIMER_REAL, &itimer);
90 startvalue.sec = itimer.it_value.tv_sec;
91 startvalue.usec = itimer.it_value.tv_usec;
94 /* Initialize the clock */
98 if (!clockInitialized) {
99 relclock_epoch.sec = relclock_epoch.usec = 0;
100 startvalue.sec = startvalue.usec = 0;
102 clockInitialized = 1;
108 /* Make clock uninitialized. */
112 clockInitialized = 0;
116 /* Compute the current time. The timer gets the current total elapsed time since startup, expressed in seconds and microseconds. This call is almost 200 usec on an APC RT */
118 clock_UpdateTime(void)
120 struct itimerval itimer;
124 getitimer(ITIMER_REAL, &itimer);
126 if (startvalue.usec >= itimer.it_value.tv_usec) {
127 offset.sec = startvalue.sec - itimer.it_value.tv_sec;
128 offset.usec = startvalue.usec - itimer.it_value.tv_usec;
130 /* The "-1" makes up for adding 1000000 usec, on the next line */
131 offset.sec = startvalue.sec - 1 - itimer.it_value.tv_sec;
132 offset.usec = startvalue.usec + 1000000 - itimer.it_value.tv_usec;
134 new.sec = relclock_epoch.sec + offset.sec;
135 new.usec = relclock_epoch.usec + offset.usec;
136 if (new.usec >= 1000000)
137 new.usec -= 1000000, new.sec++;
138 clock_now.sec = new.sec;
139 clock_now.usec = new.usec;
140 if (itimer.it_value.tv_sec < startvalue.sec / 2)
142 clock_haveCurrentTime = 1;
148 #endif /* AFS_USE_GETTIMEOFDAY */