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VHDL compiler and simulator

branch: master


NVC is a GPLv3 VHDL compiler and simulator aiming for IEEE 1076-1993 compliance. See these blog posts for background information. NVC should not be considered a production quality tool and language support is lacking in many areas. However it 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

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

Report bugs using the GitHub issue tracker.


NVC is developped on Debian Linux and has been reported to work on OS X and Windows under Cygwin. Ports to other Unix-like systems are welcome.

To build from a Git clone:

mkdir build && cd build
make install

Generating the configure script requires autoconf and automake version 1.12 or later.

To use a specific version of LLVM add --with-llvm=/path/to/llvm-config to the configure command. LLVM 3.0 or later is required.

NVC also depends on GNU Flex and Bison to generate the parser. The Bison version should be at least 2.5.

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

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 flex bison \
    libreadline-dev tcl-dev check llvm-dev

Mac OS X



Windows support is via Cygwin.

TODO: dependencies



IEEE Libraries

Due to copyright restrictions the IEEE library source files cannot be freely redistributed and must be downloaded from an external source prior to building. See lib/ieee/README for details.

To recompile the standard libraries:

make -C lib clean
make bootstrap

Note this happens automatically when installing.


To run the regression tests:

make check

The unit tests require the check library.

You may need to install additional Ruby libraries:

gem install colorize getopt

Vendor Libraries

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

  • For Xilinx ISE use ./tools/build-xilinx.rb
  • For Altera Quartus use ./tools/build-altera.rb

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

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