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RgGen is a code generation tool for ASIC/IP/FPGA/RTL engineers. It will automatically generate source code related to control and status registers (CSR), e.g. SytemVerilog RTL, UVM register model (UVM RAL/uvm_reg), C header file, Wiki documents, from human readable register map specifications.

RgGen has following features:

  • Generate source files related to CSR from register map specifications
    • RTL module
      • SystemVerilog
      • Verilog
      • VHDL
      • Supports standard bus protocols
        • AMBA APB
        • AMBA AXI4-Lite
        • Wishbone
    • UVM register model (UVM RAL/uvm_reg)
    • C header file
    • Register map documents written in Markdown
  • Register map specifications can be written in human readable format
    • Ruby with APIs to describe register map information
    • YAML
    • JSON
    • TOML
    • Spreadsheet (XLSX, ODS, CSV)
    • SiFive DUH
  • Plugin feature
    • Allow you to customize RgGen for your environment
      • Add your own special bit field types
      • Add your own host bus protocol



RgGen is written in the Ruby programing language and its required version is 3.0 or later. You need to install any of these versions of Ruby before installing RgGen tool. To install Ruby, see this page.

Installatin Command

RgGen depends on following sub components and other Ruby libraries.

To install RgGen and the dependencies, use the command below:

$ gem install rggen

RgGen and dependencies will be installed on your system root.

If you want to install them on other location, you need to specify install path and set GEM_PATH and PATH environment variables:

$ gem install --install-dir /path/to/your/install/directory rggen
$ export GEM_PATH=/path/to/your/install/directory
$ export PATH=$GEM_PATH/bin:$PATH

You would get the following error message duaring installation if you have the old RgGen (version < 0.9).

ERROR:  Error installing rggen:
        "rggen" from rggen-core conflicts with installed executable from rggen

To resolve the above error, there are three solutions. See this page

Docker Image

The rggen-docker is a Docker image to simplify installation and use of RgGen. You can also execute RgGen by using this image:

$ docker run -ti --rm -v ${PWD}:/work --user $(id -u):$(id -g) rggendev/rggen-docker:latest -c config.yml -o out block_0.yml

See the rggen-docker repository for further details.


See Wiki documents.


RgGen has plugin feature to allow your cusomization. See this Wiki document for futher detals.

Supported Tools

Following EDA tools can accept the generated source files.

  • Simulation tools
    • Synopsys VCS
    • Cadence Xcelium
    • Xilinx Vivado Simulator
    • Verilator
      • Need -Wno-unoptflat switch for Verilog RTL
    • Icarus Verilog
      • Verilog RTL only
  • Synthesis tools
    • Synopsys Design Compiler
    • Intel Quartus
    • Xilinx Vivado
    • Yosys
      • Verilog RTL


You can get sample configuration file and register map specification from the rggen-sample repository. This register map specification is for a UART IP.

You can try to use RgGen by uisng these example files. Hit command below:

$ rggen -c config.yml -o out uart_csr.yml
  • -c: Specify path to your configuration file
  • -o: Specify path to the directory where generated files will be written to

Then, generated files will be written to the out directory.

If you want to generate Verilog RTL and/or VHDL RTL then you need to instll optional plugins listed below.

$ gem install rggen-verilog
$ gem install rggen-vhdl

In addition, you need to tell RgGen to use these plugins by using the --plugin option switch:

rggen -c config.yml --plugin rggen-verilog --plugin rggen-vhdl uart_csr.yml

RgGen will generate following source files from the uart_csr.yml register map specification:


See Contributing Guide.


Feedbacks, bug reports, questions and etc. are wellcome! You can post them by using following ways:

See Also

Copyright & License

Copyright © 2019-2024 Taichi Ishitani. RgGen is licensed under the MIT License, see LICENSE for futher detils.

Code of Conduct

Everyone interacting in the RgGen project’s codebases, issue trackers, chat rooms and mailing lists is expected to follow the code of conduct.