# GHDL

> VHDL simulation software

**Wikidata**: [Q12581091](https://www.wikidata.org/wiki/Q12581091)  
**Source**: https://4ort.xyz/entity/ghdl

## Summary
GHDL is free and open-source software used for simulating VHDL (VHSIC Hardware Description Language) designs. It allows engineers and designers to verify digital circuits before physical implementation. GHDL supports multiple backends including GCC, LLVM, and mcode, making it flexible for various development environments.

## Key Facts
- GHDL is licensed under the GNU General Public License, version 2.0 or later.
- Supports the VHDL programming language (instance of Q154755).
- Available on multiple platforms including FreeBSD, NetBSD, Fedora, Ubuntu, Debian, and Arch Linux.
- Current stable release is version 4.1.0, published on April 14, 2024.
- First major stable version was 1.0.0, released February 2, 2021.
- Source code repository hosted at https://github.com/ghdl/ghdl.
- Official documentation available at https://ghdl.readthedocs.io/en/latest/.
- Has a sitelink count of 2 across Wikimedia projects but significant presence in developer communities like Stack Exchange.

## FAQs
### Q: What is GHDL used for?
A: GHDL is used for simulating VHDL code to test and verify digital circuit designs. It helps developers detect errors early in the design process without needing hardware prototypes.

### Q: Is GHDL free to use?
A: Yes, GHDL is free software distributed under the GNU General Public License v2.0 or later. Users can freely run, modify, and redistribute it.

### Q: Which operating systems support GHDL?
A: GHDL runs on several Unix-like systems including FreeBSD, NetBSD, Linux distributions such as Ubuntu, Fedora, Debian, and Arch Linux.

## Why It Matters
GHDL plays a crucial role in electronic design automation by providing an accessible platform for VHDL simulation. As a free tool, it lowers barriers for students, researchers, and professionals who want to simulate digital logic without investing in proprietary tools. Its compatibility with widely-used compilers like GCC and LLVM enhances integration into existing workflows. By enabling pre-silicon verification, GHDL contributes to faster, more reliable development cycles in FPGA and ASIC design industries.

## Notable For
- Being one of the few fully open-source VHDL simulators available.
- Supporting multiple backend execution modes: GCC, LLVM, and interpreted mcode.
- Long-term maintenance and regular updates, reaching version 4.x with continued community support.
- Integration into package managers across numerous Linux distributions and BSD variants.

## Body
### Overview
GHDL stands for “GHDL HDL Analyzer and Simulator” and serves as a command-line environment for analyzing and simulating VHDL designs. It does not provide graphical capabilities but focuses purely on functional simulation using standard VHDL constructs.

### Development & Licensing
- Licensed under the GNU General Public License (GPL), version 2.0 or later.
- Classified as free software, allowing modification and redistribution.
- Maintained via GitHub at https://github.com/ghdl/ghdl.
- Documentation is publicly hosted at https://ghdl.readthedocs.io/en/latest/.

### Supported Platforms and Packaging
GHDL has broad cross-platform availability through native builds and distribution packages:
- **Operating Systems**: FreeBSD, NetBSD, various Linux distributions.
- **Package Managers**:
  - AUR (Arch User Repository): `ghdl_gcc-git`, `ghdl-llvm-git`, `ghdl-mcode-git`
  - FreeBSD Ports: `cad/ghdl`
  - Fedora: `ghdl`
  - Ubuntu/Debian: `ghdl`
  - SlackBuilds: `development/GHDL`

### Version History Highlights
Below are selected releases showing progression over time:
- **Version 0.35** – Released December 14, 2017
- **Version 1.0.0** – First stable major release; February 2, 2021
- **Version 3.0.0** – March 8, 2023
- **Version 4.0.0** – Stable release; March 6, 2024
- **Version 4.1.0** – Latest stable release; April 14, 2024

Each version includes improvements in synthesis capability, bug fixes, and expanded IEEE library compliance.

### Technical Features
- Simulates behavioral, structural, and mixed-level VHDL descriptions.
- Backends include:
  - GCC-based compilation
  - LLVM JIT backend
  - Interpreted mcode engine
- Fully supports IEEE 1076 compliant VHDL up to certain limits depending on configuration.
- Can interface with waveform viewers like GTKWave for visualizing signal behavior.

### Community and Support
- Active discussion occurs on forums such as Stack Overflow (`https://stackoverflow.com/tags/ghdl`).
- Limited multilingual Wikipedia coverage exists in French and Korean.
- Repology tracks packaging status across repositories under project name `ghdl`.

## References

1. [Release 0.35. 2017](https://github.com/ghdl/ghdl/releases/tag/v0.35)
2. [Release 0.34. 2017](https://github.com/ghdl/ghdl/releases/tag/v0.34)
3. [Release 0.33. 2015](https://github.com/ghdl/ghdl/releases/tag/v0.33)
4. [Release 0.36. 2019](https://github.com/ghdl/ghdl/releases/tag/v0.36)
5. [Release 0.37. 2020](https://github.com/ghdl/ghdl/releases/tag/v0.37)
6. [Release 1.0.0. 2021](https://github.com/ghdl/ghdl/releases/tag/v1.0.0)
7. [2022](https://github.com/ghdl/ghdl/releases/tag/v2.0.0)
8. [Release 3.0.0. 2023](https://github.com/ghdl/ghdl/releases/tag/v3.0.0)
9. [Release 4.0.0. 2024](https://github.com/ghdl/ghdl/releases/tag/v4.0.0)
10. [Release 4.1.0. 2024](https://github.com/ghdl/ghdl/releases/tag/v4.1.0)
11. [Release 5.0.1. 2025](https://github.com/ghdl/ghdl/releases/tag/v5.0.1)
12. [Release 5.1.1. 2025](https://github.com/ghdl/ghdl/releases/tag/v5.1.1)
13. [Release 6.0.0. 2026](https://github.com/ghdl/ghdl/releases/tag/v6.0.0)