Install and Run

What Are the System Requirements?

We recommend having at least 8GB of memory and about 1GB of free disk space available for Sigasi Visual HDL (SVH).

Does SVH run on my OS?

Windows and Linux

You can check out the system requirements for your version of SVH on the Release Notes page.


SVH is not supported on MacOS. See here.

What Are the License Server Requirements?

The license server (FlexNet) is supported on

  • Red Hat Enterprise Linux 5.2 (32-bit and 64-bit) or newer
  • Windows 7 (32-bit and 64-bit) or newer

The instructions to set up the license server can be found here .

How Can I update Sigasi?

See the manual for VS Code and the manual for Eclipse.

What If I Want to Get Back to My Old Toolflow? Am I locked In?

If you ever want to get back to your old tools (we hope you won’t), you’ll have absolutely no trouble doing so. All your files are just the way you left them, except that we created two hidden files in your project folder (.project and .library_mapping.xml). You can leave them sitting there or you can delete them after you stop using our tool.

In short: you are not locked in at all!

How Does Sigasi Change My Existing Project?

You do not have to change your directory structure, the names of your VHDL files or anything in your project folder. The only thing SVH does is add a few hidden files with project information.

Can I Use Features From an Upcoming Release?

Yes! You can find the details at Sigasi Visual HDL Preview (2024.2).

Can I Have an Offline Copy of the Manual?

Yes, you can host the SVH documentation locally in your environment. Follow the steps from Hosting the Sigasi documentation in your secure and closed network.


One License Structure

If you purchase an SVH license, you can use this for either VS Code, Eclipse, or both. If you have floating licenses, each running instance of Sigasi will check out one floating license. Please note that Sigasi will be ramping down our development for Eclipse over the coming year.

Do You Sell Floating Licenses?

Absolutely. Our Sales Team will be happy to set you up with floating licenses, which are based on the well-known FlexNet (a.k.a. FlexLM) license manager.

What Are the Requirements for the License Server?

License server requirements are listed at the license server system requirements.

My New license Contains a Start Date in the Future. When Can I Start Using It?

If you’re renewing your license, the new license file can contain a start date in the future. As long as the start date is part of the VENDOR_STRING, it will not be enforced and you can start using your new license file immediately.

Getting Started

What Is a Workspace?

A workspace holds all SVH’s meta-information (preferences, project information, etc.) and serves as the default location for your projects.

Which Sigasi Files Should I Add to My Revision Control System?

Sigasi stores all project information in two files (.project and .library_mapping.xml) and one directory (.settings). If you track these files, you have everything you need.

  • .project describes all generic information on your project: which files belong to your project, etc.
  • .library_mapping.xml describes the mapping of your VHDL libraries.
  • .settings (if it exists) is a directory that contains additional settings

You can revert to older revisions of these files while Sigasi is running. Sigasi will update as soon as the files are refreshed.


What Do You Mean By “Type-Time”?

“At type-time” means “while you type.” The Sigasi development environment checks your code at type-time. In other tools, your code gets checked only after you save all files and explicitly start a compiler, but Sigasi has a type-time compiler. While you are typing, the Sigasi compiler checks your code and marks your errors.

Related terms include:

  • Save-time: the moment you you save your file
  • Elaboration-time: the moment you you set the top level of your design
  • Simulation-time (or run-time): during the simulation

Does Sigasi Support Multi-Byte Characters?

Yes, Sigasi supports all unicode characters, including Japanese. Note that the VHDL language does not allow any non-ASCII characters as identifiers, so you cannot use multi-byte characters in signal names.


How Can I Make Sigasi Generate Spaces Instead of TABs?

See the manual entries on Indentation and Whitespace for VS Code and Tabs and Spaces for Eclipse.

Where Is Path Variable Information Stored?

Path variable information is stored in the .project file. You can find more info here.

Warnings and linting rules

Can Sigasi Replace My Linter?

Depending on which features you use, it could.

But Sigasi’s linter does not aim to replace your $100,000 power lint checker with CDC (clock domain crossing) checks. Instead, Sigasi’s linter helps you get the coding conventions right first time around. In addition to style linting, Sigasi’s linter can interface with your third-party power linter tool (like Aldec ALINT), giving you feedback faster. Contact us to discuss your requirements.

How Fast Is the Sigasi linter?

Depending on your exact coding rules, the Sigasi linter can flag violations either within seconds after you type (type-time linting) or after you save (save-time linting). We can check over 80% of common coding rules at type time.

How Can I Organize My Errors and Warnings (Problem Markers) in the Problems View?

See the manual entries on Problems View for VS Code and Problems View for Eclipse.

Does SVH’s Built-In Linter Replace My Code Reviews?


The Sigasi linting functionality is aimed at freeing up time wasted in code review meetings, time wasted on trivial things like naming conventions and deprecated data types. We hope you can use this time to discuss complex design decisions and computation algorithms that have an impact on the product you are designing.

What Kind of Linting Rules Are Possible?

The answer to this question is not straightforward. However, some examples may help. We can implement (but are not limited to) the following types of custom linting rules:

  • Naming conventions (e.g. constants should be in capitals, signals should start with “s”, etc.)
  • Deprecated libraries, data types, constructs (e.g. don’t use block statements; don’t use std_logic_unsigned, etc.)
  • Project structure, file names (e.g. an entity should be in a file named “_e.vhd”)
  • Required file headers
  • Maximum sizes of files, processes, etc.
  • How to instantiate components/entities
  • Unused signals, constants, etc.
  • Dead code
  • and much more…

We cannot implement overly complex or fuzzy requirements like:

  • Post-synthesis checks
  • CDC checks
  • Fuzzy requirements like: “Entities should be sufficiently commented.” (How can an algorithm decide what is sufficient?)

If you get in touch with us, we will evaluate your coding rules to determine which rules we can implement.

I Typed an Error in my VHDL Code. Why Didn’t Sigasi Catch It?

SVH does not attempt to check the full correctness of your VHDL and Verilog code. We just run a set of syntax and “general sanity” checks. This way, 90% of common errors are caught before you even start your simulator.

As you design, you put your code through a funnel: Sigasi finds the first 90% of errors in your code, without ever running a simulation. Next, you compile with the simulator and you find another bunch of problems. In each successive step of your design flow, you find harder-to-track errors in your design. Sigasi helps you get a big number of issues out of the way early on, so that you can concentrate on finding the hard problems down the road.


Does SVH Support VHDL-2008?

SVH supports VHDL-2008 features. Inline PSL is not supported, but PSL in comments is safely ignored.

Why Don’t You Have Feature XYZ? How Can I Put It on Your Roadmap?

As any tech company, our stack of good ideas is far larger than the amount of time we have to work on them. We’re grateful for any suggestions that users send us and we often build new features based on these. However, we have to prioritize and maybe your favorite feature is not on our short-term roadmap.

Deciding which features to put on the roadmap is a very complicated process. Some of the things that help are:

  • If your feature is useful for all users, not just your specific case.
  • If your feature brings a lot of value to you and to other users. For example, a feature that saves you thirty seconds each month brings less value than something that saves you half a day each week.

Feel free to talk to us about any feature, big or small.

How Do I Create a Component Declaration (“Paste As” in Emacs)?

Some other editors (most notably Reto Zimmermann’s Emacs VHDL Mode) have the concept of “port translation”. You first copy the source code of an entity declaration, and then you can paste it as an instantiation or as a component declaration.

Sigasi supports the same, but in a different way: we use Autocomplete. You don’t need to go find the original entity declaration, since Sigasi knows where to find it in your project.

For more information, see the manual entries on Autocompletion in VS Code and see Autocompletion in Eclipse .


Sigasi Switches My Keyboard Layout! Did I Find a Bug?

This sometimes happens on Windows. You probably triggered a keyboard shortcut that switches your keyboard layout. Read Microsoft’s documentation on Language bar keyboard shortcuts . If you only use your local keyboard layout and not a standard English layout, you might as well disable the language bar.

I Get Lots of Errors in Files that Are Not Really Part of My Project. Can I Hide Them?

Legacy projects tend to accumulate files that are no longer strictly necessary. These files are still on your disk, or even in your revision control system, but the scripts don’t feed them to the simulator or to the synthesis tools any more.

We recommend removing these junk files that accumulate over time. If you are using a revision control system, you can always go back, so there is no risk to removing stale files. However, if there is a good reason to keep junk files in the project folder, you can excluded them from all libraries by ight-clicking the files and selecting Set Library > Exclude from build.

What Is a MAC Address and How Do I Find Mine?

Sigasi node-locked licenses are locked to the unique MAC address (NIC address) of your computer’s network interface. An example of a MAC address is: 00:1c:42:00:00:09.

A computer can have a long list of MAC addresses, both from physical and virtual network adapters. We recommend using a MAC address belonging to a physical network adapter since some types of virtual network adapters tend to change their MAC addresses occasionally.

You can find out which interface a MAC address belongs to depending on your OS.

  • Windows: in a command prompt, type ipconfig /all to get a detailed list of interfaces. On Windows 10 you need to avoid choosing the WiFi adapter MAC address when the random hardware addresses privacy feature is enabled . Your Sigasi license will become invalid once the WiFi MAC address changes.
  • Linux: in a terminal type /sbin/ip addr or ifconfig to obtain a detailed list. The interface for wired ethernet is usually eth0.
  • Mac OS: go to System Preferences… > Network then select the desired physical interface and select Advanced… > Hardware. Alternatively you can type ifconfig in a terminal.

Floating licenses also require a MAC address, but this needs to be the MAC address of the license server. Ask your system administrator.


Note that certain environment variables like LD_LIBRARY_PATH and LD_PRELOAD may break SVH.

Some third-party tools’ initialisation scripts set these variables to incompatible values. When this is detected by SVH, the log file contains The LD_LIBRARY_PATH has been set to: ... Note that this may cause side-effects.

If SVH fails to open the editor, state machine and block diagrams, or the documentation view, check that these variables are either undefined or empty. If they are not, try starting SVH from the command line as follows:

LD_LIBRARY_PATH="" LD_PRELOAD="" /path/to/sigasi

Where Can I Find the Log File?

Sigasi logs all internal errors to a log file. You can find this file in workspaceSigasi/.metadata/.log. The log file contains no sensitive information about your organization. On some occasions, the Sigasi Team may suggest sending them the log file to debug or improve the product. However, it remains up to you whether or not to do so.

Why Is Sigasi tTrying to Get Through My Firewall?

There are a number of reasons why Sigasi connects to the internet.

  • Updates: Each time you start Sigasi, the program checks to see if there are new updates from our website (currently located at https://download.sigasi.com). Sigasi downloads the updates in the background and, when done, it asks you if it can install them.
  • Talkback 

Enhanced Security: Customers with strict security policies can contact us to discuss compliance with their policies.

I Have Error Markers in Files that Are Not Mapped to a Library. What’s This?

Sometimes, unmapped files have error markers. This can happen if a compilation did not complete normally. You can select these errors from the Problems View and remove them by pressing delete. If you rebuild the project, no new error markers will be generated for the VHDL files that are not mapped to a library.

How Can I Undo “Exclude from Build”?

If you accidentally excluded a file from the VHDL or Verilog build, you can easily undo this by right-clicking the file again and selecting Set Library. Next, select the library in which this file needs to compiled.

If you use a version control system, you can also revert the .library_mapping.xml file. SVH will automatically pick up changes to this file and update the library information.

Other tools

Which Free VHDL Simulator Can I Use?

Sigasi does not offer simulators. If you don’t have a VHDL simulator yet, we would recommend the following simulators. You can download them free of charge.

SimulatorCommentDownload fromWindowsLinuxMacOS
Aldec Lattice EditionOnly Lattice FPGAsLattice Download page YesNoNo
Aldec Active-HDL, Student EditionStudents onlyAldec Download page YesNoNo
ModelSim-Intel FPGA EditionOnly Intel FPGAsIntel Quartus Web Edition YesYesNo
ISimOnly AMD/Xilinx FPGAsXilinx Webpack YesYesNo
GHDL Open sourceGHDL download page YesYesYes

Note that GHDL on MacOS  uses Wine, but works without problems.

We have not had good results with FreeHDL or with Green Mountain VHDL. It seems that these two projects may have been terminated.