2 % (c) The AQUA Project, Glasgow University, 1995
4 %************************************************************************
6 \section[Itimer.lc]{Interval Timer}
8 %************************************************************************
10 The interval timer is used for profiling and for context switching in the
11 threaded build. Though POSIX 1003.1b includes a standard interface for
12 such things, no one really seems to be implementing them yet. Even
13 Solaris 2.3 only seems to provide support for @CLOCK_REAL@, whereas we're
14 keen on getting access to @CLOCK_VIRTUAL@.
16 Hence, we use the old-fashioned @setitimer@ that just about everyone seems
17 to support. So much for standards.
21 #if defined(PROFILING) || defined(CONCURRENT)
23 /* OLD: # include "platform.h" */
27 # define NON_POSIX_SOURCE
31 /* As recommended in the autoconf manual */
32 # ifdef TIME_WITH_SYS_TIME
33 # include <sys/time.h>
36 # ifdef HAVE_SYS_TIME_H
37 # include <sys/time.h>
44 Handling timer events under cygwin32 is not done with signal/setitimer.
45 Instead of the two steps of first registering a signal handler to handle
46 \tr{SIGVTALRM} and then start generating them via @setitimer()@, we use
47 the Multimedia API (MM) and its @timeSetEvent@. (Internally, the MM API
48 creates a separate thread that will notify the main thread of timer
52 #if defined(cygwin32_TARGET_OS)
54 #include <windows.h> /* OK, bring it all in... */
57 vtalrm_handler is assigned and set up in
60 vtalrm_id (defined in main/Signals.lc) holds
61 the system id for the current timer (used to
62 later block/kill the timer)
65 extern TIMECALLBACK *vtalrm_cback;
68 initialize_virtual_timer(ms)
71 /* VTALRM is currently not supported by cygwin32,
72 so we use the Timer support provided by the
73 MultiMedia API that is part of Win32. The
74 parameters to timeSetEvent may require some tweaking.
76 unsigned int delay,vtalrm_id;
78 delay = timeBeginPeriod(1);
79 if (delay == TIMERR_NOCANDO) { /* error of some sort. */
83 timeSetEvent(ms, /* event every `delay' milliseconds. */
84 1, /* precision is within 5 millisecs. */
85 (LPTIMECALLBACK)vtalrm_cback,
94 initialize_virtual_timer(ms)
97 # ifndef HAVE_SETITIMER
98 fprintf(stderr, "No virtual timer on this system\n");
103 it.it_value.tv_sec = ms / 1000;
104 it.it_value.tv_usec = 1000 * (ms - (1000 * it.it_value.tv_sec));
105 it.it_interval = it.it_value;
106 return (setitimer(ITIMER_VIRTUAL, &it, NULL));
110 #endif /* !cygwin32_TARGET_OS */
113 /* This is a potential POSIX version */
115 initialize_virtual_timer(ms)
119 struct itimerspec it;
122 se.sigev_notify = SIGEV_SIGNAL;
123 se.sigev_signo = SIGVTALRM;
124 se.sigev_value.sival_int = SIGVTALRM;
125 if (timer_create(CLOCK_VIRTUAL, &se, &tid)) {
126 fprintf(stderr, "Can't create virtual timer.\n");
129 it.it_value.tv_sec = ms / 1000;
130 it.it_value.tv_nsec = 1000000 * (ms - 1000 * it.it_value.tv_sec);
131 it.it_interval = it.it_value;
132 timer_settime(tid, TIMER_RELTIME, &it, NULL);
136 #endif /* PROFILING || CONCURRENT */