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+package Time::HiRes;
+
+use strict;
+use vars qw($VERSION $XS_VERSION @ISA @EXPORT @EXPORT_OK $AUTOLOAD);
+
+require Exporter;
+use XSLoader;
+
+@ISA = qw(Exporter);
+
+@EXPORT = qw( );
+@EXPORT_OK = qw (usleep sleep ualarm alarm gettimeofday time tv_interval
+ getitimer setitimer ITIMER_REAL ITIMER_VIRTUAL ITIMER_PROF);
+
+$VERSION = '1.20_00';
+$XS_VERSION = $VERSION;
+$VERSION = eval $VERSION;
+
+sub AUTOLOAD {
+ my $constname;
+ ($constname= $AUTOLOAD) =~ s/.*:://;
+ my $val = constant($constname, @_ ? $_[0] : 0);
+ if ($!) {
+ my ($pack,$file,$line) = caller;
+ die "Your vendor has not defined Time::HiRes macro $constname, used at $file line $line.\n";
+ }
+ {
+ no strict 'refs';
+ *$AUTOLOAD = sub { $val };
+ }
+ goto &$AUTOLOAD;
+}
+
+XSLoader::load 'Time::HiRes', $XS_VERSION;
+
+# Preloaded methods go here.
+
+sub tv_interval {
+ # probably could have been done in C
+ my ($a, $b) = @_;
+ $b = [gettimeofday()] unless defined($b);
+ (${$b}[0] - ${$a}[0]) + ((${$b}[1] - ${$a}[1]) / 1_000_000);
+}
+
+# Autoload methods go after =cut, and are processed by the autosplit program.
+
+1;
+__END__
+
+=head1 NAME
+
+Time::HiRes - High resolution alarm, sleep, gettimeofday, interval timers
+
+=head1 SYNOPSIS
+
+ use Time::HiRes qw( usleep ualarm gettimeofday tv_interval );
+
+ usleep ($microseconds);
+
+ ualarm ($microseconds);
+ ualarm ($microseconds, $interval_microseconds);
+
+ $t0 = [gettimeofday];
+ ($seconds, $microseconds) = gettimeofday;
+
+ $elapsed = tv_interval ( $t0, [$seconds, $microseconds]);
+ $elapsed = tv_interval ( $t0, [gettimeofday]);
+ $elapsed = tv_interval ( $t0 );
+
+ use Time::HiRes qw ( time alarm sleep );
+
+ $now_fractions = time;
+ sleep ($floating_seconds);
+ alarm ($floating_seconds);
+ alarm ($floating_seconds, $floating_interval);
+
+ use Time::HiRes qw( setitimer getitimer
+ ITIMER_REAL ITIMER_VIRTUAL ITIMER_PROF );
+
+ setitimer ($which, $floating_seconds, $floating_interval );
+ getitimer ($which);
+
+=head1 DESCRIPTION
+
+The C<Time::HiRes> module implements a Perl interface to the usleep,
+ualarm, gettimeofday, and setitimer/getitimer system calls. See the
+EXAMPLES section below and the test scripts for usage; see your system
+documentation for the description of the underlying usleep, ualarm,
+gettimeofday, and setitimer/getitimer calls.
+
+If your system lacks gettimeofday(2) or an emulation of it you don't
+get gettimeofday() or the one-arg form of tv_interval().
+If you don't have usleep(3) or select(2) you don't get usleep()
+or sleep(). If your system don't have ualarm(3) or setitimer(2) you
+don't get ualarm() or alarm(). If you try to import an unimplemented
+function in the C<use> statement it will fail at compile time.
+
+The following functions can be imported from this module.
+No functions are exported by default.
+
+=over 4
+
+=item gettimeofday ()
+
+In array context returns a 2 element array with the seconds and
+microseconds since the epoch. In scalar context returns floating
+seconds like Time::HiRes::time() (see below).
+
+=item usleep ( $useconds )
+
+Sleeps for the number of microseconds specified. Returns the number
+of microseconds actually slept. Can sleep for more than one second
+unlike the usleep system call. See also Time::HiRes::sleep() below.
+
+=item ualarm ( $useconds [, $interval_useconds ] )
+
+Issues a ualarm call; interval_useconds is optional and will be 0 if
+unspecified, resulting in alarm-like behaviour.
+
+=item tv_interval
+
+C<tv_interval ( $ref_to_gettimeofday [, $ref_to_later_gettimeofday] )>
+
+Returns the floating seconds between the two times, which should have
+been returned by gettimeofday(). If the second argument is omitted,
+then the current time is used.
+
+=item time ()
+
+Returns a floating seconds since the epoch. This function can be
+imported, resulting in a nice drop-in replacement for the C<time>
+provided with core Perl, see the EXAMPLES below.
+
+B<NOTE 1>: this higher resolution timer can return values either less or
+more than the core time(), depending on whether your platforms rounds
+the higher resolution timer values up, down, or to the nearest to get
+the core time(), but naturally the difference should be never more than
+half a second.
+
+B<NOTE 2>: Since Sunday, September 9th, 2001 at 01:46:40 AM GMT
+(when the time() seconds since epoch rolled over to 1_000_000_000),
+the default floating point format of Perl and the seconds since epoch
+have conspired to produce an apparent bug: if you print the value of
+Time::HiRes::time() you seem to be getting only five decimals, not six
+as promised (microseconds). Not to worry, the microseconds are there
+(assuming your platform supports such granularity). What is going on
+is that the default floating point format of Perl only outputs 15
+digits. In this case that means ten digits before the decimal
+separator and five after. To see the microseconds you can use either
+printf/sprintf with C<%.6f>, or the gettimeofday() function in list
+context, which will give you the seconds and microseconds as two
+separate values.
+
+=item sleep ( $floating_seconds )
+
+Sleeps for the specified amount of seconds. Returns the number of
+seconds actually slept (a floating point value). This function can be
+imported, resulting in a nice drop-in replacement for the C<sleep>
+provided with perl, see the EXAMPLES below.
+
+=item alarm ( $floating_seconds [, $interval_floating_seconds ] )
+
+The SIGALRM signal is sent after the specfified number of seconds.
+Implemented using ualarm(). The $interval_floating_seconds argument
+is optional and will be 0 if unspecified, resulting in alarm()-like
+behaviour. This function can be imported, resulting in a nice drop-in
+replacement for the C<alarm> provided with perl, see the EXAMPLES below.
+
+=item setitimer
+
+C<setitimer ( $which, $floating_seconds [, $interval_floating_seconds ] )>
+
+Start up an interval timer: after a certain time, a signal arrives,
+and more signals may keep arriving at certain intervals. To disable
+a timer, use time of zero. If interval is set to zero (or unspecified),
+the timer is disabled B<after> the next delivered signal.
+
+Use of interval timers may interfere with alarm(), sleep(), and usleep().
+In standard-speak the "interaction is unspecified", which means that
+I<anything> may happen: it may work, it may not.
+
+In scalar context, the remaining time in the timer is returned.
+
+In list context, both the remaining time and the interval are returned.
+
+There are three interval timers: the $which can be ITIMER_REAL,
+ITIMER_VIRTUAL, or ITIMER_PROF.
+
+ITIMER_REAL results in alarm()-like behavior. Time is counted in
+I<real time>, that is, wallclock time. SIGALRM is delivered when
+the timer expires.
+
+ITIMER_VIRTUAL counts time in (process) I<virtual time>, that is, only
+when the process is running. In multiprocessor/user/CPU systems this
+may be more or less than real or wallclock time. (This time is also
+known as the I<user time>.) SIGVTALRM is delivered when the timer expires.
+
+ITIMER_PROF counts time when either the process virtual time or when
+the operating system is running on behalf of the process (such as
+I/O). (This time is also known as the I<system time>.) (Collectively
+these times are also known as the I<CPU time>.) SIGPROF is delivered
+when the timer expires. SIGPROF can interrupt system calls.
+
+The semantics of interval timers for multithreaded programs are
+system-specific, and some systems may support additional interval
+timers. See your setitimer() documentation.
+
+=item getitimer ( $which )
+
+Return the remaining time in the interval timer specified by $which.
+
+In scalar context, the remaining time is returned.
+
+In list context, both the remaining time and the interval are returned.
+The interval is always what you put in using setitimer().
+
+=back
+
+=head1 EXAMPLES
+
+ use Time::HiRes qw(usleep ualarm gettimeofday tv_interval);
+
+ $microseconds = 750_000;
+ usleep $microseconds;
+
+ # signal alarm in 2.5s & every .1s thereafter
+ ualarm 2_500_000, 100_000;
+
+ # get seconds and microseconds since the epoch
+ ($s, $usec) = gettimeofday;
+
+ # measure elapsed time
+ # (could also do by subtracting 2 gettimeofday return values)
+ $t0 = [gettimeofday];
+ # do bunch of stuff here
+ $t1 = [gettimeofday];
+ # do more stuff here
+ $t0_t1 = tv_interval $t0, $t1;
+
+ $elapsed = tv_interval ($t0, [gettimeofday]);
+ $elapsed = tv_interval ($t0); # equivalent code
+
+ #
+ # replacements for time, alarm and sleep that know about
+ # floating seconds
+ #
+ use Time::HiRes;
+ $now_fractions = Time::HiRes::time;
+ Time::HiRes::sleep (2.5);
+ Time::HiRes::alarm (10.6666666);
+
+ use Time::HiRes qw ( time alarm sleep );
+ $now_fractions = time;
+ sleep (2.5);
+ alarm (10.6666666);
+
+ # Arm an interval timer to go off first at 10 seconds and
+ # after that every 2.5 seconds, in process virtual time
+
+ use Time::HiRes qw ( setitimer ITIMER_VIRTUAL time );
+
+ $SIG{VTLARM} = sub { print time, "\n" };
+ setitimer(ITIMER_VIRTUAL, 10, 2.5);
+
+=head1 C API
+
+In addition to the perl API described above, a C API is available for
+extension writers. The following C functions are available in the
+modglobal hash:
+
+ name C prototype
+ --------------- ----------------------
+ Time::NVtime double (*)()
+ Time::U2time void (*)(UV ret[2])
+
+Both functions return equivalent information (like C<gettimeofday>)
+but with different representations. The names C<NVtime> and C<U2time>
+were selected mainly because they are operating system independent.
+(C<gettimeofday> is Un*x-centric.)
+
+Here is an example of using NVtime from C:
+
+ double (*myNVtime)();
+ SV **svp = hv_fetch(PL_modglobal, "Time::NVtime", 12, 0);
+ if (!svp) croak("Time::HiRes is required");
+ if (!SvIOK(*svp)) croak("Time::NVtime isn't a function pointer");
+ myNVtime = INT2PTR(double(*)(), SvIV(*svp));
+ printf("The current time is: %f\n", (*myNVtime)());
+
+=head1 CAVEATS
+
+Notice that the core time() maybe rounding rather than truncating.
+What this means that the core time() may be giving time one second
+later than gettimeofday(), also known as Time::HiRes::time().
+
+=head1 AUTHORS
+
+D. Wegscheid <wegscd@whirlpool.com>
+R. Schertler <roderick@argon.org>
+J. Hietaniemi <jhi@iki.fi>
+G. Aas <gisle@aas.no>
+
+=head1 REVISION
+
+$Id: HiRes.pm,v 1.20 1999/03/16 02:26:13 wegscd Exp $
+
+$Log: HiRes.pm,v $
+Revision 1.20 1999/03/16 02:26:13 wegscd
+Add documentation for NVTime and U2Time.
+
+Revision 1.19 1998/09/30 02:34:42 wegscd
+No changes, bump version.
+
+Revision 1.18 1998/07/07 02:41:35 wegscd
+No changes, bump version.
+
+Revision 1.17 1998/07/02 01:45:13 wegscd
+Bump version to 1.17
+
+Revision 1.16 1997/11/13 02:06:36 wegscd
+version bump to accomodate HiRes.xs fix.
+
+Revision 1.15 1997/11/11 02:17:59 wegscd
+POD editing, courtesy of Gisle Aas.
+
+Revision 1.14 1997/11/06 03:14:35 wegscd
+Update version # for Makefile.PL and HiRes.xs changes.
+
+Revision 1.13 1997/11/05 05:36:25 wegscd
+change version # for Makefile.pl and HiRes.xs changes.
+
+Revision 1.12 1997/10/13 20:55:33 wegscd
+Force a new version for Makefile.PL changes.
+
+Revision 1.11 1997/09/05 19:59:33 wegscd
+New version to bump version for README and Makefile.PL fixes.
+Fix bad RCS log.
+
+Revision 1.10 1997/05/23 01:11:38 wegscd
+Conditional compilation; EXPORT_FAIL fixes.
+
+Revision 1.2 1996/12/30 13:28:40 wegscd
+Update documentation for what to do when missing ualarm() and friends.
+
+Revision 1.1 1996/10/17 20:53:31 wegscd
+Fix =head1 being next to __END__ so pod2man works
+
+Revision 1.0 1996/09/03 18:25:15 wegscd
+Initial revision
+
+=head1 COPYRIGHT
+
+Copyright (c) 1996-1997 Douglas E. Wegscheid.
+All rights reserved. This program is free software; you can
+redistribute it and/or modify it under the same terms as Perl itself.
+
+=cut