Using the Verilog Simulator to Generate IRSIM .cmd Files

We will be using the functional models we developed in Verilog to create 
IRSIM .cmd files (recall that .cmd files are batch files of IRSIM commands
that you can run on .sim files created from Magic layouts).  In Verilog,
we have working modules for the datapath as well as the controller,
clock generator, and pattersource generator.  By using a special version
of Verilog to simulate these modules and by using a special "snooper" module,
we can run the same simulation on our extracted Magic layout of the datapath
with the appropriate input assertions automatically generated by the .cmd
file.  The output of the datapath (namely, the bus) from the Verilog simulation
will be compared with the output of the IRSIM simulation of the datapath
generated in Magic, and differences will be noted when running the .cmd file. 

Here is the procedure:

1.  Create the snooper module with the snoopgen program.  The input
    to the snoopgen program must be a file of inputs, outputs, and 
    bidirectional signals.  This file has already been created and is
    called datapath.in.  You will not need to change this file UNLESS 
    your IRSIM names (often the labeled signal name in your Magic layout on
    the top level) are different from the signal names in the Verilog modules.
    Here is an example of how datapath.in needs to be modified:

    i readReg_s1 readregfile
     
    where readReg_s1 is the Verilog name and readregfile is the IRSIM name.
    For vectors, only put the range on the Verilog name.  
 
    i bibus_v1[3:0] irsimbibus

    To create the snooper module, execute the following command:

    snoopgen datapath.in > snooper.v

    snooper.v has already been created for the existing datapath.in and 
    the snoopgen program is in the hw6 directory.

2.  Instantiate the snooper module somewhere.  THIS HAS ALREADY BEEN DONE in
    system.v.  Usually, you will want to instantiate the snooper module within
    the module you are checking (datapath.v) or the next one above it
    (system.v).  In either case, the snooper module must have easy access to
    the nodes it needs, the inputs and outputs of the datapath.

3.  Run rsimverilog.  rsimverilog is a special version of Verilog that we
    need for our purposes here.  Remember that our machine is executing the
    simple set of instructions in input.patterns.  As we are running our
    simulation in rsimverilog, it is creating a file called versim.cmd
    which is the .cmd file we will be using in our IRSIM simulation.  
    Therefore, it may be a good idea to run rsimverilog for a fixed period
    of time using the interactive mode of simulation.  Here is how
    rsimverilog should be called:

    rsimverilog -s *.v

    (you will see messages pass by ...)

    C1> #1000 $stop;
    C2> .

    (simulation will run until time 1000)

4.  Run IRSIM.  Before running versim.cmd on your datapath.sim file, you
    may want to set up the analyzer window and create necessary vectors
    first.  Remember that  @ versim.cmd  is the command for running
    a command file.  The simulation will run and you will see whether
    your datapath design has made any output assertion errors.  If so,
    find out why.


For more detailed information on this procedure, read snoopgen.doc which
is also in this directory.