Re: [Iverilog-devel] The string type and $value$plusargs

[Cary R. <cy...@ya...>]

Hi Niels,
Yes this should work. The problem is the plusargs code was not updated to know that a SystemVerilog string is a variable. Once that was done there is still a problem in that the string is not being updated correctly. I will look at why that is next and post again when I have this working correctly.

Interfaces are not currently supported in Icarus. Once they are I hope that the vlog95 code generator can be enhanced to emit them as normal Verilog. I think it will work, but the internal representation may put constraints on how well that will work.
Cary
 

     On Tuesday, February 10, 2015 6:35 AM, Niels Möller <ni...@ly...> wrote:
   

 I'm now trying to read a memory dump, using a command line argument for
the file name (as hinted at the end of
http://iverilog.wikia.com/wiki/Simulation).

System verilog has a string type, so I tried this program,

  module main;
    reg [64:0] mem [0:100];
    string img;
    initial begin
        if (!$value$plusargs("img=%s", img)) begin
          $display("Specify image file with +img=<image>.");
          $finish_and_return(1);
        end
        $display("Using image: %s", img);
        $readmemh(img, mem);      
        $display("Initial memory word: mem[0] = %x", mem[0]);
        $finish;
    end
  endmodule // main

I compile using

  $ iverilog -g2005-sv main.vl -o main

(with iverilog compiled from git eariler today). Works fine, so far. But
running it fails,

  $ ./main +img=../examples/hello.hex
  ERROR: main.vl:5: $value$plusargs's second argument must be a variable, found a vpiStringVar.

If I change "string img;" to "reg [300:0] img;" it works, and I get the output

  Using image:                  ../examples/hello.hex
  WARNING: main.vl:10: $readmemh(../examples/hello.hex): Not enough words in the file for the requested range [0:100].
  Initial memory word: mem[0] = 07000b4a08408e500

But that doesn't seem like a very good solution, since I have to put an
arbitrary size on the register, and it will fail with filenames which
exceed this size.

If I try the System verilog support in iverilog (primarily, I would like
to use the interface abstraction), I should be able to use the vlog95
target to generate plain verilog code which I could feed to, e.g.,
yosys, right?

Regards,
/Niels

-- 
Niels Möller. PGP-encrypted email is preferred. Keyid C0B98E26.
Internet email is subject to wholesale government surveillance.


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