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 # include "platform.h"
25 # define NON_POSIX_SOURCE
29 /* As recommended in the autoconf manual */
30 # ifdef TIME_WITH_SYS_TIME
31 # include <sys/time.h>
34 # ifdef HAVE_SYS_TIME_H
35 # include <sys/time.h>
42 Handling timer events under cygwin32 is not done with signal/setitimer.
43 Instead of the two steps of first registering a signal handler to handle
44 \tr{SIGVTALRM} and then start generating them via @setitimer()@, we use
45 the Multimedia API (MM) and its @timeSetEvent@. (Internally, the MM API
46 creates a separate thread that will notify the main thread of timer
50 #if defined(cygwin32_TARGET_OS)
52 #include <windows.h> /* OK, bring it all in... */
55 vtalrm_handler is assigned and set up in
58 vtalrm_id (defined in main/Signals.lc) holds
59 the system id for the current timer (used to
60 later block/kill the timer)
63 extern TIMECALLBACK *vtalrm_cback;
66 initialize_virtual_timer(ms)
69 /* VTALRM is currently not supported by cygwin32,
70 so we use the Timer support provided by the
71 MultiMedia API that is part of Win32. The
72 parameters to timeSetEvent may require some tweaking.
74 unsigned int delay,vtalrm_id;
76 delay = timeBeginPeriod(1);
77 if (delay == TIMERR_NOCANDO) { /* error of some sort. */
81 timeSetEvent(ms, /* event every `delay' milliseconds. */
82 1, /* precision is within 5 millisecs. */
83 (LPTIMECALLBACK)vtalrm_cback,
92 initialize_virtual_timer(ms)
95 # ifndef HAVE_SETITIMER
96 fprintf(stderr, "No virtual timer on this system\n");
101 it.it_value.tv_sec = ms / 1000;
102 it.it_value.tv_usec = 1000 * (ms - (1000 * it.it_value.tv_sec));
103 it.it_interval = it.it_value;
104 return (setitimer(ITIMER_VIRTUAL, &it, NULL));
108 #endif /* !cygwin32_TARGET_OS */
111 /* This is a potential POSIX version */
113 initialize_virtual_timer(ms)
117 struct itimerspec it;
120 se.sigev_notify = SIGEV_SIGNAL;
121 se.sigev_signo = SIGVTALRM;
122 se.sigev_value.sival_int = SIGVTALRM;
123 if (timer_create(CLOCK_VIRTUAL, &se, &tid)) {
124 fprintf(stderr, "Can't create virtual timer.\n");
127 it.it_value.tv_sec = ms / 1000;
128 it.it_value.tv_nsec = 1000000 * (ms - 1000 * it.it_value.tv_sec);
129 it.it_interval = it.it_value;
130 timer_settime(tid, TIMER_RELTIME, &it, NULL);
134 #endif /* PROFILING || CONCURRENT */