Re: [Iverilog-devel] automatically starting in noninteractive mode if standard input is not a terminal

[Lennert B. <bu...@wa...>]

On Fri, Jan 04, 2019 at 06:38:11AM +0100, Niels Möller wrote:

> > I've been using the hack patch below to make Icarus Verilog
> > automatically start in noninteractive mode when standard input is
> > not a terminal.  This is useful when you're piping test data into a
> > testbench and you don't want Ctrl-C to cause your terminal to be
> > flooded with endless output like this:
> 
> To me, it seems you'd may want to distinguish between stop due to the
> SIGINT signal, and $stop in the simulation.
> 
> And just change the SIGINT handling (set up in vvp/schedule.cc, it
> seems) to generate $finish instead of $stop, in the case that stdin
> isn't a tty.

Hello!

I was going along with what is there now, which is that the signal
handler always generates a stop, and that there is a stop_is_finish
flag which converts $stop to $finish which is set by the startup code
if you ask for noninteractive mode (-n) or set by the signal handler
if SIGHUP or SIGTERM are received.  What my patch does is basically
just act if -n is specified if standard input is not a tty.

You'd have to keep the stop_is_finish flag to implement -n, but then
you'd need an additional flag set at init time if stdin is not a tty
and check that flag from the signal handler (as I don't think you can
call isatty() from a signal handler) -- or, just split the signal
handler into two signal handlers, one that sets schedule_stopped_flag
and one that clears schedule_runnable, and then install the right one
in signals_capture() based on what mode we are in -- any preferences?