pyvcd

library0.4.1pypypi✓ verified 85d ago

pyvcd is a Python library designed for working with Value Change Dump (VCD) files. It provides functionalities for both reading and writing these standard files used to record signal activity in digital logic simulations. The current version is 0.4.1, and releases are generally made on an as-needed basis for bug fixes or minor enhancements.

data serialization

pip install pyvcd

github ↗package ↗homepage ↗

INSTALL

IMPORT

SIG · PYVCD

pyvcd

datapythonv0.4.1

Install

1.5s avg

Import

—

Disk

16MB

Pass rate

10/ 10

Env Coverage10 / 10

glibc

3.9–3.13

musl

3.9–3.13

Install & Compatibility

Where this runs

tested against v0.4.1 · pip install

no network on importno background threads

Install × environment matrix

Each cell = how many times install + import succeeded across repeated harness runs. Partial = flaky.
glibc = Debian/Ubuntu slim · musl = Alpine Linux

musl

py 3.10–3.910 runs

installs and imports cleanly · install 0.0s · import 0.000s · 17.9MB

glibc

py 3.10–3.910 runs

installs and imports cleanly · install 1.5s · import 0.000s · 18MB

16MB installed

● package 16MB

Code

Verified usage

Verified import paths — ran on the pinned version, not inferred.

VCDWriter

✓ from vcd import VCDWriter

✗ from pyvcd import VCDWriter

VCDPhaseError

✓ from vcd import VCDPhaseError

reader

✓ from vcd import reader

This example demonstrates how to create a VCD file, define a module scope, declare signals (wires), and record their value changes over time using `VCDWriter`.

from datetime import datetime from pyvcd import VCDWriter # Create a VCD file named 'test.vcd' with VCDWriter(open('test.vcd', 'w'), timescale='1 ns', date=datetime.now()) as writer: # Enter a scope named 'top' of type 'module' scope = writer.scope_stack.enter_scope('top', 'module') # Define a 1-bit 'clk' wire and change its value over time writer.change(scope.var('clk', 'wire', 1), 0, 0) # At time 0, clk is 0 writer.change(scope.var('clk', 'wire', 1), 1, 100) # At time 100 ns, clk is 1 writer.change(scope.var('clk', 'wire', 1), 0, 200) # At time 200 ns, clk is 0 # Define another 1-bit 'rst_n' wire writer.change(scope.var('rst_n', 'wire', 1), 1, 0) writer.change(scope.var('rst_n', 'wire', 1), 0, 100) writer.change(scope.var('rst_n', 'wire', 1), 1, 200) # Leave the current scope writer.scope_stack.leave_scope() print("VCD file 'test.vcd' generated successfully.")

Debug

Known issues

gotchaForgetting to use `VCDWriter` in a `with` statement or manually `close()` the writer can lead to incomplete or corrupted VCD files, as internal buffers might not be flushed to disk.

fix

Always use `VCDWriter` as a context manager: `with VCDWriter(open('file.vcd', 'w'), ...) as writer:`

affects: All

gotchaThe `timescale` argument to `VCDWriter` is crucial for the correct interpretation of timestamps by VCD viewers. Missetting it (e.g., '1ps' when the simulation operates in '1ns' increments) will result in incorrect timing displays.

fix

Ensure `timescale` (e.g., '1 ns', '1 ps', '1 us') accurately reflects the time units used for your simulation data.

affects: All

gotchaSignal values are expected to be integers for `wire` types by default. Providing non-integer values without proper conversion can lead to `TypeError` or `ValueError` or incorrect data representation in the VCD file.

fix

Ensure values passed to `writer.change()` for `wire` types are integers. For bit-string representations, consider converting to integer or ensuring your VCD viewer handles them correctly.

affects: All

Upgrade

Version history

0.4.1latest on PyPI · released Nov 10, 2024

Audit

Dependencies

No dependency data recorded yet.

Agent activity

4 hits · last 30 days

node

Resources

githubhttps://github.com/westerndigitalcorporation/pyvcd ↗

packagehttps://pypi.org/project/pyvcd/ ↗

homepagehttp://pyvcd.readthedocs.io/en/latest/ ↗