Import a project in Sigasi Visual HDL from `.f` files

Dot-f (.f) files are a ‘de facto’ standard for exchanging project information between EDA tools and managing HDL files in bigger FPGA and ASIC projects. In this article we discuss the .f file format, its limitations, and how to use it to create a Sigasi Visual HDL (SVH) project from your HDL code and .f file(s).

The dot-F format

.f files contain a list of command line options for an EDA tool, often an HDL simulator. The .f extension originates from the fact that these command line option files are specified on the command line with the -f option, as in

$ my_eda_tool -f file.f

In other words, .f is hardly a file format. .f files contain a collection of (usually UNIX-style) command line options. As options are EDA tool and EDA vendor dependent, .f files may be generated for specific EDA tools, and may contain different information depending on the tool for which they’re intended. EDA tools that generate .f files for other tools may in fact generate a set of .f files, e.g. one for each popular simulator.

Still, there is enough commonality between .f files to handle them as a file type. .f files contain the following elements:

• file names of the design files, optionally with wildcards (*)
• options starting with a dash, like -o, -p value, -f another_dotF_file.f or --option=value
• options starting with a plus, like +incdir+/include/path
• comments: lines starting with //, # or ! or text enclosed in /* */
• lines may be concatenated with the continuation character \
• entries may include environment variables $VAR or ${VAR}

Some .f files are just a collection of file names, while others contain other elements as well. Parsing of these files is not particularly difficult, but, as mentioned, the semantics may be different depending on the tool for which they’re intended.

Limitations of dot-F files

Obviously, .f files have some limitations when they’re used to capture project information.

First of all, they’re meant to be used with a particular tool, so any project information which is irrelevant to this particular tool is not included.

A number of tools, e.g. some simulation library compilers, may need multiple runs to compile an entire project because each compiler run can only handle one design library. This is mainly the case for VHDL projects, because (System)Verilog projects usually use one single library. In such case, a .f file may only contain files associated with one library, and the library name may not even be present in the .f file.

Also further information, e.g. the VHDL or Verilog language version, may or may not be present in a .f file.

So why do we still want to use dot-F files?

Well, actually, that’s probably because no vendor-neutral format exists to communicate HDL project information between EDA tools. Despite the limitations, it’s one of the few things that exist to save design engineers from creating and maintaining a collection of in-house scripts (often in a polyglot of tcl, perl, shell scripts, python and maybe other languages) for that purpose.

A further plus is that .f files are text files, so they’re human readable and easy to generate and to parse. And finally, any missing information in a .f file may conveniently be added on the command line, e.g.

$ my_eda_tool -f file.f --other-option ...

Creating a SVH project from dot-F files

Sigasi offers support for .f files in the open-source Sigasi Project Creator . This tool is written in Python and Antlr, and may assist you with setting up a SVH project from one or more .f files. Sigasi Project Creator is offered under a BSD license . SVH users are welcome to contact us for support . Your contribution to improve the Sigasi Project Creator is also welcome :-)

So far, the Sigasi Project Creator supports:

• input files (mapped to library work)
• +incdir+... (Verilog includes, added to Verilog preferences)
• +define+... (Verilog defines, added to Verilog preferences)
• -makelib <libname> ... -endlib with input files on separate lines between makelib and endlib, with continuation characters (mapped to the library <libname>, or the part of libname after the last slash (/) if it contains any)
• -f <filename> to include another .f file
• environment variables in input files and include paths (which get expanded if they are defined)
• VHDL, (System)Verilog and mixed language projects
• multiple top-level .f files

Prior to using Sigasi Project Creator, you’ll need to have Python3  and the Sigasi Project Creator  on your system. Also install the required Python packages:

python -m pip install -r requirements.txt

Finally, go to the directory which will be your project root and run the Project Creator. For simple projects, any .f file should work. For more complex projects with different libraries and include paths, a .f file should be chosen which preferably has the relevant information, e.g. a .f file for Cadence IUS.

python /my/path/SigasiProjectCreator/src/createSigasiProject.py projectname path/to/my.f

Further command line options of createSigasiProject.py are discussed here . After this, you should see two new files and a folder in your current directory: .project, .library_mapping.xml and .settings.

You can open the project in SVH using File > Open Projects from File System…. Click Directory…, select the project directory, then click Select Folder and Finish to open the project.

Some errors may remain due to e.g. missing library or (System)Verilog include path information in the .f file. SVH will help you resolve the errors. The library mapping can be updated in the Projects View. Missing include paths may often be fixed using a quick fix. With little or no further effort, your project is fully set up.