kevinmehall / rust-vcd

Read and write VCD (Value Change Dump) files in Rust

VCD

Documentation | Changelog

This crate reads and writes VCD (Value Change Dump) files, a common format used with logic analyzers, HDL simulators, and other EDA tools. It provides streaming wrappers around the io::Read and io::Write traits to read and write VCD commands and data.

rust-vcd's Issues

Publish a new version?

Is there anything else that should be done before publishing a new version? I'm currently depending on the git head for the fixes, but I'd like to be able to follow a release instead.

The IdCode hashing doesn't avoid collisions

The most trivial case: ! and !! both map to 0. In fact, !ident and ident will always map to the same thing for any ident.

Changing i - ID_CHAR_MIN to i - ID_CHAR_MIN + 1 would still run into collisions after integer overflow.

Variable declaration with bit selection or range produces errors.

I get the following error, even though my VCD file is correct. Correct in the sense that gtkwave reads it.
Error: Custom { kind: InvalidData, error: StringError("expected $end") }

gtkwave is able to process the following line, but rust-vcd is not.
$var wire 2 a signal [4:0] $end

Do you plan to support this?
After reading the IEEE spec I am still unsure if the space is valid or not.

Extended timescale support

Using simvision to dump the results of a mixed-mode simulation run under XCELIUM produces this header:

$comment
TOOL:	simvision(64)	20.03-s014
$end

$date
    Apr 10, 2021 09:30:35
$end

$timescale
    0.0001fs
$end

Yes, this is 100 zs…

Publish a new version

Please publish a version to crates.io that includes #10. This issue is blocking sgpthomas/vcdump#1
Thanks!

Doesn't support enough variable types

I tried to parse a VCD output by a SymbiYosys run, and found that this failed on the integer and event types.

Malformed 'b' signal data can be generated

Hello! Thanks for making this awesome lib! I have an application which generates an malformed vcd using the interface, which I found surprising.

sbasu@ubuntu:~/Devel/rust-hdl2/rust-hdl/rust-hdl$ gtkwave ./i2c_driver.vcd 

GTKWave Analyzer v3.3.86 (w)1999-2017 BSI

[0] start time.
[100000000] end time.
GTKWAVE | malformed 'b' signal data for 'uut.driver.scl' after time_idx = 1

Here is an example of line in the .vcd file that I think causes the problem:

bz "

I suspect that the problem is that I am writing a single (scalar) value to a vector. I can probably fix this in the application, but if you are interested, I can submit a PR to handle it in the library as well.

`Writer` missing `flush` method

there's no way to call io::Write::flush on the internal writer

Doesn't support top-level variables or multiple top-level scopes

Just splitting this issue off #2 for documentation purposes.

This fails:

$var wire 1 ! foo $end
$enddefinitions $end