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NVC is a GPLv3 VHDL compiler and simulator aiming for IEEE 1076-2002 compliance. See these blog posts for background information. NVC has been successfully used to simulate several real-world designs.

Brief usage example:

$ nvc -a my_design.vhd my_tb.vhd
$ nvc -e my_tb
$ nvc -r my_tb

Or more succinctly, as a single command:

$ nvc -a my_design.vhd my_tb.vhd -e my_tb -r

The full manual can be read after installing NVC using man nvc or online.

Report bugs using the GitHub issue tracker.


NVC is developed on Debian Linux and is regularly tested on OS X and Windows under MSYS2. Ports to other systems are welcome.

NVC has both a release branch and a development master branch. The master branch should be stable enough for day-to-day use and has comprehensive regression tests, but the release branch is more suitable for third party packaging. The latest released version is 1.5. Significant changes since the last release are detailed in

To build from a Git clone:

mkdir build && cd build
make install

Generating the configure script requires autoconf 2.63 and automake 1.11 or later.

To build from a released tarball:

sudo make install

To use a specific version of LLVM add --with-llvm=/path/to/llvm-config to the configure command. LLVM 7, 8, and 9 have all been tested.

NVC also depends GNU Flex to generate the lexical analyser.

If a readline-compatible library is installed it will be used to provide line editing in the interactive mode.

GtkWave can be used to view simulation waveforms. Version 3.3.79 or later is reqiured for the default FST format.

Debian and Ubuntu

On a Debian derivative the following should be sufficient to install all required dependencies:

sudo apt-get install build-essential automake autoconf autoconf-archive flex \
    check llvm-dev pkg-config zlib1g-dev curl

Mac OS X

The easiest way to install NVC on OS X is with Homebrew.

brew install nvc

This will install the latest stable version. The current git master can be installed with

brew install --HEAD nvc

To build from source follow the generic instructions above.


Windows support is via MinGW or Cygwin.

If you do not already have Cygwin it is easiest to build for MinGW using MSYS2. Install the following dependencies using pacman. For 64-bit MSYS2 replace i686 below with x86_64.

pacman -S base-devel mingw-w64-i686-{llvm,ncurses,libffi,check,pkg-config}
export PATH=/mingw32/bin:$PATH     # Or mingw64 for 64-bit
mkdir build && cd build
make install

For Cygwin use setup.exe to install either gcc or clang and the following dependencies: automake, autoconf, pkg-config, llvm, libllvm-devel, flex, libffi-devel, libcurses-devel, curl, and make. Then follow the standard installation instructions above.


Install the dependencies with pkg_add:

pkg_add -r automake-1.15p0 autoconf-2.69p2 libexecinfo llvm check libexecinfo

Use a modern compiler such as Clang to build, as the system GCC does not support many modern language features.

./configure --with-llvm=/usr/local/bin/llvm-config CC=clang CXX=clang++

Then follow the generic instructions above.

IEEE Libraries

The source files for the IEEE standard libraries are included in the repository for convenience but the license forbids distribution of modifications. See lib/ieee/ for details. These files can also be downloaded from the IEEE SA.

To recompile the standard libraries:

make bootstrap

Note this happens automatically when installing.


To run the regression tests:

make check

The unit tests require the check library.


NVC supports a small subset of VHDL-2008 which can be enabled with the --std=2008 option. If you require library functions from the 2008 standard you can use the VHDL-2008 Support Library which provides backwards-compatible implementations for VHDL-1993. Run ./tools/build-2008-support.rb to download and install this.

Vendor Libraries

NVC provides scripts to compile the simulation libraries of common FPGA vendors.

  • For Xilinx ISE use ./tools/build-xilinx-ise.rb
  • For Xilinx Vivado use ./tools/build-xilinx-vivado.rb
  • For Altera Quartus use ./tools/build-altera.rb
  • For Lattice iCEcube2 use ./tools/build-lattice.rb

The libraries will be installed under ~/.nvc/lib.

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