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This is the Verilator Package README file.


This package is Copyright 2003-2013 by Wilson Snyder. (Report bugs to http://www.veripool.org/.)

Verilator is free software; you can redistribute it and/or modify it under the terms of either the GNU Lesser General Public License Version 3 or the Perl Artistic License Version 2.0. (See the documentation for more details.)

This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.


Verilator converts synthesizable (generally not behavioral) Verilog code into C++ or SystemC code. It is not a complete simulator, just a translator.

Verilator is invoked with parameters similar to GCC or Synopsys's VCS. It reads the specified Verilog code, lints it, and optionally adds coverage code. For C++ format, it outputs .cpp and .h files. For SystemC format, it outputs .cpp and .h files using the standard SystemC headers.

The resulting files are then compiled with C++. The user writes a little C++ wrapper file, which instantiates the top level module. This is compiled in C++, and linked with the Verilated files.

The resulting executable will perform the actual simulation.


Verilator is developed and has primary testing on Ubuntu. Versions have also built on Redhat Linux, Macs OS-X, HPUX and Solaris. It should run with minor porting on any Linix-ish platform. Verilator also works on Windows under Cygwin, and Windows under MinGW (gcc -mno-cygwin). Verilated output (not Verilator itself) compiles under MSVC++ 2008 and newer.


For more details see http://www.veripool.org/projects/verilator/wiki/Installing.

If you will be modifying Verilator, you should use the "git" method as it will let you track changes.

  • The latest version is available at http://www.veripool.org/verilator.

    Download the latest package from that site, and decompress.

    tar xvzf verilator_version.tgz
  • If you will be using SystemC (vs straight C++ output), download SystemC from http://www.systemc.org. Follow their installation instructions. You will need to set SYSTEMC_INCLUDE to point to the include directory with systemc.h in it, and SYSTEMC_LIBDIR to points to the directory with libsystemc.a in it. (Older installations may set SYSTEMC and SYSTEMC_ARCH instead.)

  • If you will be using SystemPerl or coverage, download and install System-Perl, http://www.veripool.org/systemperl. Note you'll need to set a SYSTEMPERL environment variable to point to the downloaded kit. Optionally also set SYSTEMPERL_INCLUDE to point to the installed headers.

  • You will need the flex and bison packages installed.

  • cd to the Verilator directory containing this README.

  • You now have to decide how you're going to eventually install the kit.

    Note Verilator builds the current value of VERILATOR_ROOT, SYSTEMC_INCLUDE, SYSTEMC_LIBDIR, SYSTEMPERL, and SYSTEMPERL_INCLUDE as defaults into the executable, so try to have them correct before configuring.

    1. Our personal favorite is to always run Verilator from the kit directory. This allows the easiest experimentation and upgrading. It's also how most EDA tools operate; to run you point to the tarball, no install is needed.

      export VERILATOR_ROOT=`pwd`   # if your shell is bash
      setenv VERILATOR_ROOT `pwd`   # if your shell is csh
    2. To install globally onto a "cad" disk with multiple versions of every tool, and add it to path using Modules/modulecmd:

      unset VERILATOR_ROOT      # if your shell is bash
      unsetenv VERILATOR_ROOT   # if your shell is csh
      # For the tarball, use the version number instead of git describe
      ./configure --prefix /CAD_DISK/verilator/`git describe | sed "s/verilator_//"`
      After installing you'll want a module file like the following:
      set install_root /CAD_DISK/verilator/{version-number-used-above}
      setenv VERILATOR_ROOT $install_root
      prepend-path PATH $install_root/bin
      prepend-path MANPATH $install_root/man
    3. The next option is to install it globally, using the normal system paths:

      unset VERILATOR_ROOT      # if your shell is bash
      unsetenv VERILATOR_ROOT   # if your shell is csh
    4. Alternatively you can configure a prefix that install will populate, as most GNU tools support:

      unset VERILATOR_ROOT      # if your shell is bash
      unsetenv VERILATOR_ROOT   # if your shell is csh
      ./configure --prefix /opt/verilator-VERSION

      Then after installing you will need to add /opt/verilator-VERSION/bin to PATH.

  • Type make to compile Verilator.

    Type make test to check the compilation.

    Configure with --enable-longtests for more complete developer tests. Additional packages may be required for these tests.

    You may get a error about a typedef conflict for uint32_t. Edit verilated.h to change the typedef to work, probably to @samp{typedef unsigned long uint32_t;}.

  • If you used the VERILATOR_ROOT scheme you're done. Programs should set the environment variable VERILATOR_ROOT to point to this distribution, then execute $VERILATOR_ROOT/bin/verilator, which will find the path to all needed files.

    If you used the prefix scheme, now do a make install. To run verilator, have the verilator binary directory in your PATH (this should already be true if using the default configure), and make sure VERILATOR_ROOT is not set.


Detailed documentation and the man page can be seen by running:

bin/verilator --help

or reading verilator.txt in the same directory as this README.


The directories in the kit after de-taring are as follows:

bin/verilator               => Compiler Wrapper invoked to Verilate code
include/                    => Files that should be in your -I compiler path
include/verilated*.cpp      => Global routines to link into your simulator
include/verilated*.h        => Global headers
include/verilated.v         => Stub defines for linting
include/verilated.mk        => Common makefile
src/                        => Translator source code
test_v                      => Example Verilog code for other test dirs
test_c                      => Example Verilog->C++ conversion
test_sc                     => Example Verilog->SystemC conversion
test_sp                     => Example Verilog->SystemPerl conversion
test_vcs                    => Example Verilog->VCS conversion (test the test)
test_verilated              => Internal tests
test_regress                => Internal tests


See verilator.txt (or execute bin/verilator --help) for limitations.