Copyright - Yehowshua Immanuel

A High performance, VCD Parser written in Rust

Current Features

• Robust Error Handling

  FastWave currently offers highly robust error handling(at least on the sample VCD files in this repository) which GTKWave doesn't have. For example, selecting the UTILIZATON_ENABLED signal after opening test2x2_regex22_string1.vcd (one of the sample xilinx vcd test files) in GtkWave, will crash GtkWave since this signal is malformed. FastWave on the otherhand simply notes that the signal is malformed.

Performance

Methods

I have been testing performance on a 3.04GB VCD file that can be found here.

For getting the GtkWave results, I fired up GtkWave, clicked on File->Open New Window, and selected the VCD file linked to above. I started my stopwatch as soon as I pressed enter to beging loading the VCD file, and stopped my stopwatch once the GtkWave titlebar reached 100%.

To get the memory consumption, I opened Activity Monitor on Mac, and recorded the GtkWave memory usage before and after loading the large VCD file, and took the difference.

I noticed that when running FastWave in the VsCode terminal as opposed to the MacOS system terminal or the Lapce terminal, FastWave is notably slower.

Results

Software	Time(s)	Memory(MB)
FastWave	~27.30	1100+
GtkWave	~30	89.8

Current Limitations

Unable to handle VCD files that have signals with more than 2^32 - 1 = 4,294,967,295 deltas/changes.

Running

This repository comes with several smaller VCD files emitted from various EDA tools. If you want a larger VCD file, grab one from here.

The first build of the program may take some time.

cargo run --release test-vcd-files/aldec/SPI_Write.vcd

You can run all the tests with cargo test

Testing on Bad Files

You may wish to test the parser on a malformed VCD just to make sure that the parser gives useful/sane errors.

Here's a command to test on a malformed VCD: cargo run --release test-vcd-files/VCD_file_with_errors.vcd

TODO

Features and Other

• add timeline value scanner code
• test against large waveform directly within SpinalHDL
• (a bit of work) consolidate error messages in validation phase
• be explicit with imports, remove exports as possible once FastWave is known to be fairly stable.
• do a read through all the code
  • make contents of src/types.rs public as necessary.
• Print out git commit or release number.
• Take a look at GTKWave parser to compare efficiency.
• Move part of the performance section to another markdown file.

Repairs

• make a custom date parser for possibly up to 18 different versions(that is, for each possible tool).
• Consolidate error messages and add cursors throughout.
• Fix warnings especially usage and restriction warnings once I'm able to successfully parse all sample VCDs.

Code Consistency

• Change error messages to line and filenames. Go through all calls to unwrap.
  • search for any unwraps or any direct vectors indexing
• Handle TODOs
• Remove debug code/comments.

Documentation

• Document indexing structure with diagram and possibly include the rational

Marketing

• Send survey to community