From: "Suraj N. Kurapati" <skurapat@...>
Date: 2006-07-24T05:32:41+09:00
Subject: Re: [ANN] Ruby-VPI 0.7

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Phil Tomson wrote:
> It's great to see more EDA tools based on Ruby and it looks like
>  you've put a lot of work into this.

Thanks for the encouragement. :)

> One nitpick:  The link to RHDL in your user's guide should be 
> updated to point to: http://rhdl.rubyforge.org/
> 
> Also, I'm not sure if RHDL is an 'alternative'.

Fixed.

> In fact I wonder if it might be possible to use RubyVPI and RHDL
> together sort of as a distributed simulator where part of your
> code is simulating in the Verilog simulator and part is
> simulating in RHDL?

Interesting, it should be possible. I see three possible scenarios:

1. RHDL communicates with a Verilog simulator through Ruby-VPI. This
would simply add VPI capabilities to RHDL's verification framework.

2. Ruby-VPI communicates with RHDL (acting as a Verilog simulator).
This would make it necessary for RHDL to implement the vpi_user.h
interface in C/Ruby (probably not what you intended :).

3. Ruby-VPI acts a bridge between two simulations that are running
in parallel: one in RHDL and another in a Verilog simulator. This
could be useful when you need to verify the behavior of an RHDL
module against one implemented in Verilog.

For example, say you have synthesizable RTL source code for an
existing mircoprocessor that implements the SPARC v8 ISA, and you're
writing your own microprocessor in RHDL which also implements the
SPARC v8 ISA.

Now comes the challenge: you'd like to verify that your
microprocessor correctly implements the ISA. One approach is to feed
the same input to your RHDL microprocessor and the Verilog one, and
then verify that they both generate the same output or exhibit the
same behavior.

> BTW: I believe there is some support for VPI in the ghdl vhdl 
> simulator ( http://ghdl.free.fr ) so RubyVPI may be usable with 
> ghdl.

Thanks for the tip. I wouldn't have guessed a VHDL simulator has VPI
capabilities! I should try adding VHPI capabilites for my project,
in the future.
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