vcd_rust

A value change dump parser for the Rust programming language.

The goal for this project is to parse VCD files into a similar data structure as yaml-cpp does for YAML files, create understandable data structure representations of a VCD file, and provide clear error messages if parsing fails.

What is value change dump?

Value change dump is a file format specifying how a digital waveform appears. It's mainly used for digital waveform viewers, among other electronic design automation (EDA) tools. You can read more about it on it's Wikipedia article.

Example

The below file example is a simplified version of the file on the VCD Wikipedia article. Given this file named example.vcd with the contents:

$date August 9th, 2020 $end
$version 1.0 $end
$comment This is an example $end
$timescale 1 ps $end
$scope module top $end
$var wire 8 # data $end
$upscope $end
$enddefinitions $end
$dumpvars
bxxxxxxxx #
$end
#0
b10000001 #
#5
b10101010 #

This file can be parsed with the load_from_file() method:

extern crate vcd_rust;
use vcd_rust::{load_from_file, types::timescale::{TimeScale, TimeUnit}};

fn main() {
    let vcd = load_from_file("example.vcd").unwrap();
    assert_eq!(vcd.date, "August 9th, 2020"); // Date
    assert_eq!(vcd.version, "1.0"); // Version
    assert_eq!(vcd.comments, vec!["This is an example"]); // Comments as a vector
    assert_eq!(vcd.timescale, TimeScale::init(1, TimeUnit::PS)); // Custom type for timescale
    // ...among other data structures
}

Likewise, the string representation of a VCD file can be parsed with the load_from_string() method:

extern crate vcd_rust;
use vcd_rust::{load_from_string, vcd::VCD};

fn parse_vcd_string() -> VCD {
    let vcd_string = "$date August 9th, 2020 $end...";  // etc.
    return load_from_string(vcd_string).unwrap();
}

References

• Explanation of VCD format