sv2v: SystemVerilog to Verilog

sv2v converts SystemVerilog (IEEE 1800-2017) to Verilog (IEEE 1364-2005), with an emphasis on supporting synthesizable language constructs.

The primary goal of this project is to create a completely free and open-source tool for converting SystemVerilog to Verilog. While methods for performing this conversion already exist, they generally either rely on commercial tools, or are limited in scope.

This project was originally developed to target Yosys, and so allows for disabling the conversion of (passing through) those SystemVerilog features which Yosys supports.

Dependencies

All of sv2v's dependencies are free and open-source.

• Build Dependencies
  • Haskell Stack - Haskell build system
  • Haskell dependencies are managed in sv2v.cabal
• Test Dependencies
  • Icarus Verilog - for Verilog simulation
  • shUnit2 - test framework

Installation

Pre-built binaries

We plan on releasing pre-built binaries in the future.

Building from source

You must have Stack installed to build sv2v. Then you can:

git clone https://github.com/zachjs/sv2v.git
cd sv2v
make

This creates the executable at ./bin/sv2v. Stack takes care of installing exact (compatible) versions of the compiler and sv2v's build dependencies.

You can install the binary to your local bin path (typically ~/.local/bin) by running stack install, or copy over the executable manually.

Usage

sv2v takes in a list of files and prints the converted Verilog to stdout. Users may specify include search paths, define macros during preprocessing, and exclude some of the conversions.

Below is the current usage printout. This interface is subject to change.

sv2v [OPTIONS] [FILES]

Common flags:
  -e --exclude=CONV         exclude a particular conversion (always,
                            interface, logic)
  -i --incdir=DIR           add directory to include search path
  -d --define=NAME[=VALUE]  define a macro for preprocessing
  -? --help                 Display help message
  -V --version              Print version information
     --numeric-version      Print just the version number

Supported Features

sv2v supports most synthesizable SystemVerilog features. Current notable exceptions include export, interfaces with parameter bindings, and complex (non-identifier) modport expressions. Assertions are also supported, but are simply dropped during conversion.

If you find a bug or have a feature request, please create an issue. Preference will be given to issues which include examples or test cases.

SystemVerilog Front End

This project contains a preprocessor and lexer, a parser, and an abstract syntax tree representation for a subset of the SystemVerilog specification. The parser is not very strict. The AST allows for the representation of syntactically (and semantically) invalid Verilog. The goal is to be more general in the representation to enable more standardized and straightforward conversion procedures. This could be extended into an independent and more fully-featured front end if there is significant interest.

Testing

The current test suite is limited. Tests can be run with make test.

Acknowledgements

This project was originally forked from Tom Hawkin's Verilog parser. While the front end has changed substantially to parse a different language, his project was a great starting point.

Reid Long was invaluable in developing this tool, providing significant tests and advice, and isolating many bugs. His projects can be found here.

Edric Kusuma helped me with the ins and outs of SystemVerilog, with which I had no prior experience, and has also helped with test cases.

License

See the LICENSE file for copyright and licensing information.