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OpenASIP - Open Application-Specific Instruction-set Processor toolset

OpenASIP is an open application-specific instruction-set processor (ASIP) toolset for design and programming of customized co-processors (typically programmable accelerators).

The toolset provides a complete retargetable co-design flow from high-level language programs down to FPGA/ASIC synthesizable processor RTL (VHDL and Verilog generation supported) and instruction-parallel program binaries.

Processor customization points include the register files, function units, supported operations, and the datapath interconnection network.

The internal processor template of OpenASIP is based on the energy efficient and modular Transport Triggered Architecture (TTA), which is still its default target programming model for static multi-issue designs. OpenASIP, however, also has initial support for other programming models such as standard operation-based VLIW (demonstrated in Blocks CGRA) and since 2.0 it received the first features to support customizing RISC-V ISA based processors.

OpenASIP has been developed by several researchers (and research assistants) of Tampere University (Finland) and various other international contributors since the early 2003.


  • OpenASIP project source code is licensed with LGPL v2.1.
  • Generated hardware description files are licensed with a more permissive MIT license, to allow the designer more freedom to choose the licensing of the produced processors.
  • Read more in LICENSE.txt


(*) OpenASIP was previously called TTA-based Co-Design Environment (TCE). After adding support for other ISAs than TTAs, its name was changed to a more general one to describe its wider utility.

In case you use OpenASIP in your own research, please cite one or more of the following papers that is/are the most relevant to the topic (overall TCE, softcores/FPGA or RISC-V customization):

  author="J{\"a}{\"a}skel{\"a}inen, Pekka and Viitanen, Timo and Takala, Jarmo and Berg, Heikki",  
  editor="Hussain, Waqar and Nurmi, Jari and Isoaho, Jouni and Garzia, Fabio",  
  title="HW/SW Co-design Toolset for Customization of Exposed Datapath Processors",  
  bookTitle="Computing Platforms for Software-Defined Radio",  
  publisher="Springer International Publishing",  
  title={Customized exposed datapath soft-core design flow with compiler support},  
  author={Esko, Otto and J{\"a}{\"a}skelainen, Pekka and Huerta, Pablo and Carlos, S and Takala, Jarmo and Martinez, Jose Ignacio},  
  booktitle={2010 International Conference on Field Programmable Logic and Applications},  
  title={OpenASIP 2.0: Co-Design Toolset for RISC-V Application-Specific Instruction-SetProcessors},  
  author={Hepola, Kari and Multanen, Joonas and J{\"a}{\"a}skel{\"a}inen, Pekka},  
  booktitle={2022 IEEE 33rd International Conference on Application-specific Systems, Architectures and Processors (ASAP)},  

Supported Operating Systems

OpenASIP requires a Unix-style operating system such as Linux. Debian-based distributions like Debian and Ubuntu should have most of the required libraries included, but other recent distribution versions should work fine too. MacOS support is experimental.

The following installation steps install prerequisities, the OpenASIP-patched LLVM and OpenASIP to in $HOME/local.

Installing Prerequisities

This step needs root/admin privileges.

For Ubuntus, you need to enable the universe and multiverse repositories first:

Ubuntu 20.04+ / Debian 11

sudo apt-get install libwxgtk3.0-gtk3-dev libboost-all-dev \
tcl8.6-dev libedit-dev libsqlite3-dev sqlite3 libxerces-c-dev g++ make \
latex2html libffi-dev autoconf automake libtool subversion git cmake graphviz

Ubuntu 18.04 LTS and older

Not supported anymore due to SQLite version too low (currently requires 3.25+)

Debian 10

sudo apt-get install libwxgtk3.0-dev libboost-{filesystem,graph,regex,thread}-dev \
tcl8.6-dev libedit-dev libsqlite3-dev sqlite3 libxerces-c-dev g++ make latex2html \
libffi-dev autoconf automake libtool subversion git cmake

Debian 9 and older

Not supported anymore due to SQLite version too low (currently requires 3.25+)

Red Hat Enterprise Linux 8 & clones

sudo yum install -y wxGTK3-devel boost-devel tcl-devel libedit-devel \
sqlite-devel xerces-c-devel gcc-c++ make autoconf automake libtool git svn

Get the Latest OpenASIP Source Code

git clone openasip-devel

Alternatively you can get one of the release branches, e.g.:

git clone -b openasip-2.1 openasip-2.1

LLVM and Clang

In order to compile programs from C/C++ with OpenASIP, you need to install LLVM and Clang with a few additional patches and use correct LLVM build switches to fix some issues affecting OpenASIP usage.

You can do this easiest as follows:

cd openasip-devel/openasip
./tools/scripts/ $HOME/local

Alternatively, if you cloned the release branch:

cd openasip-2.1/openasip
./tools/scripts/ $HOME/local

After successful installation, add information about installed libraries to the search path. We assume OpenASIP will be installed to the same location later.

export PATH=$HOME/local/bin:$PATH
export LDFLAGS=-L$HOME/local/lib

You might want to put the above environment variable modification commands to your ~/.bashrc or similar so they are taken in effect automatically whenever you start a new shell. Otherwise you need to remember to enter them before attempting to use LLVM or OpenASIP.

Notice that OpenASIP and LLVM installation folder comes first in the path variable. This is to prevent OpenASIP of using system's LLVM installation. This might interfere with other tools in your system which rely on using system's LLVM installation. If this is the case, then better option is to put above lines to a separate file and place this file somewhere in your path or home directory. Now when you open a new shell and need to use OpenASIP, just source this file to your shell with:



If you wish to build OpenASIP with support for RISC-V, you need to install the following prerequisites before installing OpenASIP. RISC-V GNU Toolchain ( (version 12.1.0+) for common bintools and elf2hex ( for generating hex files from RISC-V ELF files.

The easiest way to acquire there tools is to use the included installation script:

./tools/scripts/ $HOME/local

Make sure your installation directory is added to PATH correctly:

export PATH=$HOME/local/bin:$PATH

Building and Installing OpenASIP

In the root of OpenASIP sources (e.g. openasip-devel/openasip), run:

./ && ./configure --prefix=$HOME/local && make -j8 && make install

Now OpenASIP commands such as ttasim should work. Check this with:

ttasim --version

Now try to run the smoke test script to see if it finds any problems with your installation:

Then run the smoke test script:

oa-selftest -v

If this finished correctly, you are all set! For learning to use OpenASIP, a good way is to start with the OpenASIP user manual's (openasip/manual/OpenASIP_manual.pdf) tutorials, e.g., the "OpenASIP tour" that goes through the basic TTA customization aspects. The RISC-V customization features are demonstrated in the "RISC-V Tutorial".

Upgrading OpenASIP

Later on, if you want to update your OpenASIP installation with the latest changes committed in the version control system, you can do the following steps:

Update the source code modifications:

cd openasip-devel/openasip
git pull

Build and install the updated OpenASIP:

make && make install

Further information of library and tools prerequisite versions

These are the current prerequisites for libraries and tools required to build OpenASIP:

Host compiler Supported versions
GCC 9.0+
Clang 16 to 17
Library Supported versions Library license
Xerces-C++ 2.3.0+ Apache v2.0
wxWidgets 2.8+ wxWidgets
Tcl 8.0-8.4 BSD-style
Boost 1.48.0-1.53.0 very permissive
sqlite3 3.2.0+ public domain
LLVM 16-17 LLVM Release License
Editline 2.9 BSD-style
Python 3.6+ PSF license

Please remember to install the '-dev' versions of the packages in order to get the library headers which are need to compile client code against them. You also need a version of "GNU Make" to build OpenASIP.


Editline is used for command line editing/history browsing capabilities to the command line interface of the simulator.

You can download the sources here:

Note: this library might require 'termcap' library in some distributions. The package is named 'libedit-dev' in Debian-based distributions.


The development files of the following Boost libraries are required by OpenASIP . regexp . spirit . filesystem . format . thread . graph . tupl

Some distributions, like Fedora Core, include all Boost libraries in a single package, but some, like Debian, have separated them in several packages.