Clock devices which call sim_register_clock_unit or sim_register_clock_unit_tmr
are best behaved if they use sim_activate_after to schedule their tick events.
The RUN command implicitly resets all devices which may have unexpected
consequences for a novice user.
The logic now produces a warning about this side effect when more than one
RUN command is executed in the same simulator session.
An explicit RESET command suppresses this warning for a subsequent RUN
command.
A RUN command with the -Q switch also suppresses this warning.
When the timer subsystem hasn't gotten fully initialized, devices may
attempt to coschedule schedule events before the clock has gotten
far enough along to be fully initialized. When this happens we now
make sure to avoid the potential for a zero delay which will may cause
an infinite scheduling loop.
Asynchronous clocks are now built for all simulators which are built with
SIM_ASYNCH_IO defined. The default behavior has asynchronous clocks
disabled since this is still experimental, but it can be enabled with
SET TIMER ASYNC.
Catchup clock ticks are now available, but since they're experimental,
they aren't enabled by default. Catchup ticks are only available if the
simulators clock device calls sim_rtcn_tick_ack to acknowledge processing
of clock ticks. The VAX simulators have been modified to leverage this.
Catchup clock ticks can be enabled with SET TIMER CATCHUP
Additionally, an idle threshold is provided which can be used to
influence when clock calibration may be suppressed. The default is not
to suppress calibration activities.
The various timer behaviors are visible with the SHOW TIMER command.
The state of the operating timer facilities is visible with: SHOW CLOCK
Timer events which are queued are visible with the SHOW QUEUE command.
Polling is now done at least every 500ms even if the prior input
character hasn't been processed yet. This allows ^E to provide a way
to exit a simulator which otherwise isn't reading from the console port.
clang doesn't like the -R option, it wants the long form -Wl,-R. gcc is ok
with either.
clang on OS X doesn't like that form, but the change is only in a
conditional which is relevant when X11R7 is installed and that isn't the
case for OS X.
