[Iverilog-devel] periodic updating of vcd file

[Joshua S. <kni...@gm...>]

Dear Sirs:

I am trying to add periodic updates to the vcd file output by icarus during
simulation using vvp.exe.  I want to be able to update the file so I can
read it with another vcd program, but I need to call fclose on the dumpfile
in sys_vcd.c

Sorry but I'm a noob at coding in c++, so any help would be deeply
appreciated.

I am wondering what the best way to get access to this function is.

I tried to add a header called sys_vcd.h to the vpi folder. This just
contained an extern declaration of the function that I wanted access to in
sys_vcd.c. However, i also added a string so that I could make sure it was
working.

extern void reopen_dumpfile(void);
char cake[] = "WHAT IS UP";


I then included the file in vvp/schedule.cc. I found that I could access
the string from schedule.cc but not the function. I assume this is because
I initialized the string in the header, but the actual definition of the
function is contained in sys_vcd.c.

How do I go about giving myself access to this function? As I remember, I
think to get the actual definition, I need access to the object file
sys_vcd.o.

S I thought I could just change the makefile in the vvp folder like so:

V = vpi_modules.o vpi_callback.o vpi_const.o vpi_event.o vpi_iter.o
vpi_mcd.o \
vpi_priv.o vpi_scope.o vpi_real.o vpi_signal.o vpi_tasks.o vpi_time.o \
vpi_vthr_vector.o vpip_bin.o vpip_hex.o vpip_oct.o \
vpip_to_dec.o vpip_format.o vvp_vpi.o ../vpi/sys_vcd.o


but this didn't work. the makefile gives some error message:
mv: cannot move ../vpi/sys_vcd.d to dep/../vpi/sys_vcd.d : no such file or
directory.

I have no idea what this error means. I feel like the object file should
contain the definition of the function I added to the header.

Does anyone know what i'm doing wrong? i feel like it's really obvious, but
I'm stumped.

Also I get the feeling that probably the original intent of the icarus
developers was for me not to access vpi headers from inside the vvp folder.
Should I add a function to the vpi library instead? I know it already
handles commands like $dumpflush, $dumpvars, etc.

Regardless, I just want the ability to regularly flush and close the vcd
file so that it updates with new data periodically or when a pause command
is sent. then I could update the graph with this updated vcd file.


Josh